| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Peter Zijlstra | 7465 | 45.49% | 64 | 29.36% |
| Ingo Molnar | 3852 | 23.47% | 14 | 6.42% |
| Lei Ming | 1013 | 6.17% | 11 | 5.05% |
| Steven Rostedt | 728 | 4.44% | 13 | 5.96% |
| Junjiro R. Okajima | 519 | 3.16% | 3 | 1.38% |
| Byungchul Park | 383 | 2.33% | 6 | 2.75% |
| Alfredo Alvarez Fernandez | 338 | 2.06% | 2 | 0.92% |
| Paul E. McKenney | 290 | 1.77% | 8 | 3.67% |
| Dave Jones | 212 | 1.29% | 4 | 1.83% |
| Huang Ying | 160 | 0.98% | 2 | 0.92% |
| Matthew Wilcox | 141 | 0.86% | 2 | 0.92% |
| Maarten Lankhorst | 116 | 0.71% | 1 | 0.46% |
| David S. Miller | 110 | 0.67% | 1 | 0.46% |
| Bart Van Assche | 101 | 0.62% | 5 | 2.29% |
| Dmitriy Vyukov | 97 | 0.59% | 2 | 0.92% |
| Hitoshi Mitake | 85 | 0.52% | 2 | 0.92% |
| Jarek Poplawski | 85 | 0.52% | 5 | 2.29% |
| Oleg Nesterov | 63 | 0.38% | 5 | 2.29% |
| Yong Zhang | 59 | 0.36% | 3 | 1.38% |
| Frédéric Weisbecker | 56 | 0.34% | 5 | 2.29% |
| Boqun Feng | 53 | 0.32% | 1 | 0.46% |
| Tetsuo Handa | 46 | 0.28% | 3 | 1.38% |
| Waiman Long | 42 | 0.26% | 4 | 1.83% |
| Arjan van de Ven | 40 | 0.24% | 3 | 1.38% |
| Frank Rowand | 40 | 0.24% | 1 | 0.46% |
| Nicholas Piggin | 35 | 0.21% | 2 | 0.92% |
| Pavel Emelyanov | 30 | 0.18% | 1 | 0.46% |
| Ben Hutchings | 28 | 0.17% | 1 | 0.46% |
| Tejun Heo | 23 | 0.14% | 4 | 1.83% |
| Thomas Gleixner | 22 | 0.13% | 4 | 1.83% |
| Colin Cross | 19 | 0.12% | 1 | 0.46% |
| Andi Kleen | 18 | 0.11% | 4 | 1.83% |
| Borislav Petkov | 16 | 0.10% | 2 | 0.92% |
| Andrew Morton | 15 | 0.09% | 1 | 0.46% |
| Gregory Haskins | 14 | 0.09% | 1 | 0.46% |
| Ben Greear | 14 | 0.09% | 1 | 0.46% |
| Sasha Levin | 10 | 0.06% | 1 | 0.46% |
| Mike Frysinger | 10 | 0.06% | 1 | 0.46% |
| Jason Baron | 7 | 0.04% | 1 | 0.46% |
| Tony Luck | 6 | 0.04% | 1 | 0.46% |
| Rabin Vincent | 5 | 0.03% | 1 | 0.46% |
| Andreas Gruenbacher | 5 | 0.03% | 1 | 0.46% |
| Kent Overstreet | 4 | 0.02% | 1 | 0.46% |
| Joel A Fernandes | 4 | 0.02% | 2 | 0.92% |
| Alexey Dobriyan | 3 | 0.02% | 1 | 0.46% |
| Heiko Carstens | 3 | 0.02% | 1 | 0.46% |
| Srivatsa S. Bhat | 3 | 0.02% | 1 | 0.46% |
| Nikolay Borisov | 3 | 0.02% | 1 | 0.46% |
| Dale Farnsworth | 2 | 0.01% | 1 | 0.46% |
| Yi Zhu | 2 | 0.01% | 1 | 0.46% |
| Dmitry Eremin-Solenikov | 2 | 0.01% | 1 | 0.46% |
| Li Zefan | 2 | 0.01% | 1 | 0.46% |
| Fengguang Wu | 2 | 0.01% | 1 | 0.46% |
| Gautham R. Shenoy | 1 | 0.01% | 1 | 0.46% |
| John Kacur | 1 | 0.01% | 1 | 0.46% |
| Paul Walmsley | 1 | 0.01% | 1 | 0.46% |
| Johannes Berg | 1 | 0.01% | 1 | 0.46% |
| Lai Jiangshan | 1 | 0.01% | 1 | 0.46% |
| Mandeep Singh Baines | 1 | 0.01% | 1 | 0.46% |
| Lucas De Marchi | 1 | 0.01% | 1 | 0.46% |
| Hong Zhi Guo | 1 | 0.01% | 1 | 0.46% |
| Total | 16409 | 218 |
/* * kernel/lockdep.c * * Runtime locking correctness validator * * Started by Ingo Molnar: * * Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra * * this code maps all the lock dependencies as they occur in a live kernel * and will warn about the following classes of locking bugs: * * - lock inversion scenarios * - circular lock dependencies * - hardirq/softirq safe/unsafe locking bugs * * Bugs are reported even if the current locking scenario does not cause * any deadlock at this point. * * I.e. if anytime in the past two locks were taken in a different order, * even if it happened for another task, even if those were different * locks (but of the same class as this lock), this code will detect it. * * Thanks to Arjan van de Ven for coming up with the initial idea of * mapping lock dependencies runtime. */ #define DISABLE_BRANCH_PROFILING #include <linux/mutex.h> #include <linux/sched.h> #include <linux/sched/clock.h> #include <linux/sched/task.h> #include <linux/sched/mm.h> #include <linux/delay.h> #include <linux/module.h> #include <linux/proc_fs.h> #include <linux/seq_file.h> #include <linux/spinlock.h> #include <linux/kallsyms.h> #include <linux/interrupt.h> #include <linux/stacktrace.h> #include <linux/debug_locks.h> #include <linux/irqflags.h> #include <linux/utsname.h> #include <linux/hash.h> #include <linux/ftrace.h> #include <linux/stringify.h> #include <linux/bitops.h> #include <linux/gfp.h> #include <linux/random.h> #include <linux/jhash.h> #include <linux/nmi.h> #include <asm/sections.h> #include "lockdep_internals.h" #define CREATE_TRACE_POINTS #include <trace/events/lock.h> #ifdef CONFIG_PROVE_LOCKING int prove_locking = 1; module_param(prove_locking, int, 0644); #else #define prove_locking 0 #endif #ifdef CONFIG_LOCK_STAT int lock_stat = 1; module_param(lock_stat, int, 0644); #else #define lock_stat 0 #endif /* * lockdep_lock: protects the lockdep graph, the hashes and the * class/list/hash allocators. * * This is one of the rare exceptions where it's justified * to use a raw spinlock - we really dont want the spinlock * code to recurse back into the lockdep code... */ static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; static int graph_lock(void) { arch_spin_lock(&lockdep_lock); /* * Make sure that if another CPU detected a bug while * walking the graph we dont change it (while the other * CPU is busy printing out stuff with the graph lock * dropped already) */ if (!debug_locks) { arch_spin_unlock(&lockdep_lock); return 0; } /* prevent any recursions within lockdep from causing deadlocks */ current->lockdep_recursion++; return 1; } static inline int graph_unlock(void) { if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) { /* * The lockdep graph lock isn't locked while we expect it to * be, we're confused now, bye! */ return DEBUG_LOCKS_WARN_ON(1); } current->lockdep_recursion--; arch_spin_unlock(&lockdep_lock); return 0; } /* * Turn lock debugging off and return with 0 if it was off already, * and also release the graph lock: */ static inline int debug_locks_off_graph_unlock(void) { int ret = debug_locks_off(); arch_spin_unlock(&lockdep_lock); return ret; } unsigned long nr_list_entries; static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES]; /* * All data structures here are protected by the global debug_lock. * * Mutex key structs only get allocated, once during bootup, and never * get freed - this significantly simplifies the debugging code. */ unsigned long nr_lock_classes; #ifndef CONFIG_DEBUG_LOCKDEP static #endif struct lock_class lock_classes[MAX_LOCKDEP_KEYS]; static inline struct lock_class *hlock_class(struct held_lock *hlock) { if (!hlock->class_idx) { /* * Someone passed in garbage, we give up. */ DEBUG_LOCKS_WARN_ON(1); return NULL; } return lock_classes + hlock->class_idx - 1; } #ifdef CONFIG_LOCK_STAT static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats); static inline u64 lockstat_clock(void) { return local_clock(); } static int lock_point(unsigned long points[], unsigned long ip) { int i; for (i = 0; i < LOCKSTAT_POINTS; i++) { if (points[i] == 0) { points[i] = ip; break; } if (points[i] == ip) break; } return i; } static void lock_time_inc(struct lock_time *lt, u64 time) { if (time > lt->max) lt->max = time; if (time < lt->min || !lt->nr) lt->min = time; lt->total += time; lt->nr++; } static inline void lock_time_add(struct lock_time *src, struct lock_time *dst) { if (!src->nr) return; if (src->max > dst->max) dst->max = src->max; if (src->min < dst->min || !dst->nr) dst->min = src->min; dst->total += src->total; dst->nr += src->nr; } struct lock_class_stats lock_stats(struct lock_class *class) { struct lock_class_stats stats; int cpu, i; memset(&stats, 0, sizeof(struct lock_class_stats)); for_each_possible_cpu(cpu) { struct lock_class_stats *pcs = &per_cpu(cpu_lock_stats, cpu)[class - lock_classes]; for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++) stats.contention_point[i] += pcs->contention_point[i]; for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++) stats.contending_point[i] += pcs->contending_point[i]; lock_time_add(&pcs->read_waittime, &stats.read_waittime); lock_time_add(&pcs->write_waittime, &stats.write_waittime); lock_time_add(&pcs->read_holdtime, &stats.read_holdtime); lock_time_add(&pcs->write_holdtime, &stats.write_holdtime); for (i = 0; i < ARRAY_SIZE(stats.bounces); i++) stats.bounces[i] += pcs->bounces[i]; } return stats; } void clear_lock_stats(struct lock_class *class) { int cpu; for_each_possible_cpu(cpu) { struct lock_class_stats *cpu_stats = &per_cpu(cpu_lock_stats, cpu)[class - lock_classes]; memset(cpu_stats, 0, sizeof(struct lock_class_stats)); } memset(class->contention_point, 0, sizeof(class->contention_point)); memset(class->contending_point, 0, sizeof(class->contending_point)); } static struct lock_class_stats *get_lock_stats(struct lock_class *class) { return &this_cpu_ptr(cpu_lock_stats)[class - lock_classes]; } static void lock_release_holdtime(struct held_lock *hlock) { struct lock_class_stats *stats; u64 holdtime; if (!lock_stat) return; holdtime = lockstat_clock() - hlock->holdtime_stamp; stats = get_lock_stats(hlock_class(hlock)); if (hlock->read) lock_time_inc(&stats->read_holdtime, holdtime); else lock_time_inc(&stats->write_holdtime, holdtime); } #else static inline void lock_release_holdtime(struct held_lock *hlock) { } #endif /* * We keep a global list of all lock classes. The list only grows, * never shrinks. The list is only accessed with the lockdep * spinlock lock held. */ LIST_HEAD(all_lock_classes); /* * The lockdep classes are in a hash-table as well, for fast lookup: */ #define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1) #define CLASSHASH_SIZE (1UL << CLASSHASH_BITS) #define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS) #define classhashentry(key) (classhash_table + __classhashfn((key))) static struct hlist_head classhash_table[CLASSHASH_SIZE]; /* * We put the lock dependency chains into a hash-table as well, to cache * their existence: */ #define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1) #define CHAINHASH_SIZE (1UL << CHAINHASH_BITS) #define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS) #define chainhashentry(chain) (chainhash_table + __chainhashfn((chain))) static struct hlist_head chainhash_table[CHAINHASH_SIZE]; /* * The hash key of the lock dependency chains is a hash itself too: * it's a hash of all locks taken up to that lock, including that lock. * It's a 64-bit hash, because it's important for the keys to be * unique. */ static inline u64 iterate_chain_key(u64 key, u32 idx) { u32 k0 = key, k1 = key >> 32; __jhash_mix(idx, k0, k1); /* Macro that modifies arguments! */ return k0 | (u64)k1 << 32; } void lockdep_off(void) { current->lockdep_recursion++; } EXPORT_SYMBOL(lockdep_off); void lockdep_on(void) { current->lockdep_recursion--; } EXPORT_SYMBOL(lockdep_on); /* * Debugging switches: */ #define VERBOSE 0 #define VERY_VERBOSE 0 #if VERBOSE # define HARDIRQ_VERBOSE 1 # define SOFTIRQ_VERBOSE 1 #else # define HARDIRQ_VERBOSE 0 # define SOFTIRQ_VERBOSE 0 #endif #if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE /* * Quick filtering for interesting events: */ static int class_filter(struct lock_class *class) { #if 0 /* Example */ if (class->name_version == 1 && !strcmp(class->name, "lockname")) return 1; if (class->name_version == 1 && !strcmp(class->name, "&struct->lockfield")) return 1; #endif /* Filter everything else. 1 would be to allow everything else */ return 0; } #endif static int verbose(struct lock_class *class) { #if VERBOSE return class_filter(class); #endif return 0; } /* * Stack-trace: tightly packed array of stack backtrace * addresses. Protected by the graph_lock. */ unsigned long nr_stack_trace_entries; static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES]; static void print_lockdep_off(const char *bug_msg) { printk(KERN_DEBUG "%s\n", bug_msg); printk(KERN_DEBUG "turning off the locking correctness validator.\n"); #ifdef CONFIG_LOCK_STAT printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n"); #endif } static int save_trace(struct stack_trace *trace) { trace->nr_entries = 0; trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries; trace->entries = stack_trace + nr_stack_trace_entries; trace->skip = 3; save_stack_trace(trace); /* * Some daft arches put -1 at the end to indicate its a full trace. * * <rant> this is buggy anyway, since it takes a whole extra entry so a * complete trace that maxes out the entries provided will be reported * as incomplete, friggin useless </rant> */ if (trace->nr_entries != 0 && trace->entries[trace->nr_entries-1] == ULONG_MAX) trace->nr_entries--; trace->max_entries = trace->nr_entries; nr_stack_trace_entries += trace->nr_entries; if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) { if (!debug_locks_off_graph_unlock()) return 0; print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!"); dump_stack(); return 0; } return 1; } unsigned int nr_hardirq_chains; unsigned int nr_softirq_chains; unsigned int nr_process_chains; unsigned int max_lockdep_depth; #ifdef CONFIG_DEBUG_LOCKDEP /* * Various lockdep statistics: */ DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats); #endif /* * Locking printouts: */ #define __USAGE(__STATE) \ [LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \ [LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \ [LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\ [LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R", static const char *usage_str[] = { #define LOCKDEP_STATE(__STATE) __USAGE(__STATE) #include "lockdep_states.h" #undef LOCKDEP_STATE [LOCK_USED] = "INITIAL USE", }; const char * __get_key_name(struct lockdep_subclass_key *key, char *str) { return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str); } static inline unsigned long lock_flag(enum lock_usage_bit bit) { return 1UL << bit; } static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit) { char c = '.'; if (class->usage_mask & lock_flag(bit + 2)) c = '+'; if (class->usage_mask & lock_flag(bit)) { c = '-'; if (class->usage_mask & lock_flag(bit + 2)) c = '?'; } return c; } void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS]) { int i = 0; #define LOCKDEP_STATE(__STATE) \ usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \ usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ); #include "lockdep_states.h" #undef LOCKDEP_STATE usage[i] = '\0'; } static void __print_lock_name(struct lock_class *class) { char str[KSYM_NAME_LEN]; const char *name; name = class->name; if (!name) { name = __get_key_name(class->key, str); printk(KERN_CONT "%s", name); } else { printk(KERN_CONT "%s", name); if (class->name_version > 1) printk(KERN_CONT "#%d", class->name_version); if (class->subclass) printk(KERN_CONT "/%d", class->subclass); } } static void print_lock_name(struct lock_class *class) { char usage[LOCK_USAGE_CHARS]; get_usage_chars(class, usage); printk(KERN_CONT " ("); __print_lock_name(class); printk(KERN_CONT "){%s}", usage); } static void print_lockdep_cache(struct lockdep_map *lock) { const char *name; char str[KSYM_NAME_LEN]; name = lock->name; if (!name) name = __get_key_name(lock->key->subkeys, str); printk(KERN_CONT "%s", name); } static void print_lock(struct held_lock *hlock) { /* * We can be called locklessly through debug_show_all_locks() so be * extra careful, the hlock might have been released and cleared. */ unsigned int class_idx = hlock->class_idx; /* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfields: */ barrier(); if (!class_idx || (class_idx - 1) >= MAX_LOCKDEP_KEYS) { printk(KERN_CONT "<RELEASED>\n"); return; } printk(KERN_CONT "%p", hlock->instance); print_lock_name(lock_classes + class_idx - 1); printk(KERN_CONT ", at: %pS\n", (void *)hlock->acquire_ip); } static void lockdep_print_held_locks(struct task_struct *p) { int i, depth = READ_ONCE(p->lockdep_depth); if (!depth) printk("no locks held by %s/%d.\n", p->comm, task_pid_nr(p)); else printk("%d lock%s held by %s/%d:\n", depth, depth > 1 ? "s" : "", p->comm, task_pid_nr(p)); /* * It's not reliable to print a task's held locks if it's not sleeping * and it's not the current task. */ if (p->state == TASK_RUNNING && p != current) return; for (i = 0; i < depth; i++) { printk(" #%d: ", i); print_lock(p->held_locks + i); } } static void print_kernel_ident(void) { printk("%s %.*s %s\n", init_utsname()->release, (int)strcspn(init_utsname()->version, " "), init_utsname()->version, print_tainted()); } static int very_verbose(struct lock_class *class) { #if VERY_VERBOSE return class_filter(class); #endif return 0; } /* * Is this the address of a static object: */ #ifdef __KERNEL__ static int static_obj(void *obj) { unsigned long start = (unsigned long) &_stext, end = (unsigned long) &_end, addr = (unsigned long) obj; /* * static variable? */ if ((addr >= start) && (addr < end)) return 1; if (arch_is_kernel_data(addr)) return 1; /* * in-kernel percpu var? */ if (is_kernel_percpu_address(addr)) return 1; /* * module static or percpu var? */ return is_module_address(addr) || is_module_percpu_address(addr); } #endif /* * To make lock name printouts unique, we calculate a unique * class->name_version generation counter. The caller must hold the graph * lock. */ static int count_matching_names(struct lock_class *new_class) { struct lock_class *class; int count = 0; if (!new_class->name) return 0; list_for_each_entry(class, &all_lock_classes, lock_entry) { if (new_class->key - new_class->subclass == class->key) return class->name_version; if (class->name && !strcmp(class->name, new_class->name)) count = max(count, class->name_version); } return count + 1; } static inline struct lock_class * look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass) { struct lockdep_subclass_key *key; struct hlist_head *hash_head; struct lock_class *class; if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) { debug_locks_off(); printk(KERN_ERR "BUG: looking up invalid subclass: %u\n", subclass); printk(KERN_ERR "turning off the locking correctness validator.\n"); dump_stack(); return NULL; } /* * If it is not initialised then it has never been locked, * so it won't be present in the hash table. */ if (unlikely(!lock->key)) return NULL; /* * NOTE: the class-key must be unique. For dynamic locks, a static * lock_class_key variable is passed in through the mutex_init() * (or spin_lock_init()) call - which acts as the key. For static * locks we use the lock object itself as the key. */ BUILD_BUG_ON(sizeof(struct lock_class_key) > sizeof(struct lockdep_map)); key = lock->key->subkeys + subclass; hash_head = classhashentry(key); /* * We do an RCU walk of the hash, see lockdep_free_key_range(). */ if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) return NULL; hlist_for_each_entry_rcu(class, hash_head, hash_entry) { if (class->key == key) { /* * Huh! same key, different name? Did someone trample * on some memory? We're most confused. */ WARN_ON_ONCE(class->name != lock->name); return class; } } return NULL; } /* * Static locks do not have their class-keys yet - for them the key is * the lock object itself. If the lock is in the per cpu area, the * canonical address of the lock (per cpu offset removed) is used. */ static bool assign_lock_key(struct lockdep_map *lock) { unsigned long can_addr, addr = (unsigned long)lock; if (__is_kernel_percpu_address(addr, &can_addr)) lock->key = (void *)can_addr; else if (__is_module_percpu_address(addr, &can_addr)) lock->key = (void *)can_addr; else if (static_obj(lock)) lock->key = (void *)lock; else { /* Debug-check: all keys must be persistent! */ debug_locks_off(); pr_err("INFO: trying to register non-static key.\n"); pr_err("the code is fine but needs lockdep annotation.\n"); pr_err("turning off the locking correctness validator.\n"); dump_stack(); return false; } return true; } /* * Register a lock's class in the hash-table, if the class is not present * yet. Otherwise we look it up. We cache the result in the lock object * itself, so actual lookup of the hash should be once per lock object. */ static struct lock_class * register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) { struct lockdep_subclass_key *key; struct hlist_head *hash_head; struct lock_class *class; DEBUG_LOCKS_WARN_ON(!irqs_disabled()); class = look_up_lock_class(lock, subclass); if (likely(class)) goto out_set_class_cache; if (!lock->key) { if (!assign_lock_key(lock)) return NULL; } else if (!static_obj(lock->key)) { return NULL; } key = lock->key->subkeys + subclass; hash_head = classhashentry(key); if (!graph_lock()) { return NULL; } /* * We have to do the hash-walk again, to avoid races * with another CPU: */ hlist_for_each_entry_rcu(class, hash_head, hash_entry) { if (class->key == key) goto out_unlock_set; } /* * Allocate a new key from the static array, and add it to * the hash: */ if (nr_lock_classes >= MAX_LOCKDEP_KEYS) { if (!debug_locks_off_graph_unlock()) { return NULL; } print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!"); dump_stack(); return NULL; } class = lock_classes + nr_lock_classes++; debug_atomic_inc(nr_unused_locks); class->key = key; class->name = lock->name; class->subclass = subclass; INIT_LIST_HEAD(&class->locks_before); INIT_LIST_HEAD(&class->locks_after); class->name_version = count_matching_names(class); /* * We use RCU's safe list-add method to make * parallel walking of the hash-list safe: */ hlist_add_head_rcu(&class->hash_entry, hash_head); /* * Add it to the global list of classes: */ list_add_tail(&class->lock_entry, &all_lock_classes); if (verbose(class)) { graph_unlock(); printk("\nnew class %px: %s", class->key, class->name); if (class->name_version > 1) printk(KERN_CONT "#%d", class->name_version); printk(KERN_CONT "\n"); dump_stack(); if (!graph_lock()) { return NULL; } } out_unlock_set: graph_unlock(); out_set_class_cache: if (!subclass || force) lock->class_cache[0] = class; else if (subclass < NR_LOCKDEP_CACHING_CLASSES) lock->class_cache[subclass] = class; /* * Hash collision, did we smoke some? We found a class with a matching * hash but the subclass -- which is hashed in -- didn't match. */ if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass)) return NULL; return class; } #ifdef CONFIG_PROVE_LOCKING /* * Allocate a lockdep entry. (assumes the graph_lock held, returns * with NULL on failure) */ static struct lock_list *alloc_list_entry(void) { if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) { if (!debug_locks_off_graph_unlock()) return NULL; print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!"); dump_stack(); return NULL; } return list_entries + nr_list_entries++; } /* * Add a new dependency to the head of the list: */ static int add_lock_to_list(struct lock_class *this, struct list_head *head, unsigned long ip, int distance, struct stack_trace *trace) { struct lock_list *entry; /* * Lock not present yet - get a new dependency struct and * add it to the list: */ entry = alloc_list_entry(); if (!entry) return 0; entry->class = this; entry->distance = distance; entry->trace = *trace; /* * Both allocation and removal are done under the graph lock; but * iteration is under RCU-sched; see look_up_lock_class() and * lockdep_free_key_range(). */ list_add_tail_rcu(&entry->entry, head); return 1; } /* * For good efficiency of modular, we use power of 2 */ #define MAX_CIRCULAR_QUEUE_SIZE 4096UL #define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1) /* * The circular_queue and helpers is used to implement the * breadth-first search(BFS)algorithem, by which we can build * the shortest path from the next lock to be acquired to the * previous held lock if there is a circular between them. */ struct circular_queue { unsigned long element[MAX_CIRCULAR_QUEUE_SIZE]; unsigned int front, rear; }; static struct circular_queue lock_cq; unsigned int max_bfs_queue_depth; static unsigned int lockdep_dependency_gen_id; static inline void __cq_init(struct circular_queue *cq) { cq->front = cq->rear = 0; lockdep_dependency_gen_id++; } static inline int __cq_empty(struct circular_queue *cq) { return (cq->front == cq->rear); } static inline int __cq_full(struct circular_queue *cq) { return ((cq->rear + 1) & CQ_MASK) == cq->front; } static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem) { if (__cq_full(cq)) return -1; cq->element[cq->rear] = elem; cq->rear = (cq->rear + 1) & CQ_MASK; return 0; } static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem) { if (__cq_empty(cq)) return -1; *elem = cq->element[cq->front]; cq->front = (cq->front + 1) & CQ_MASK; return 0; } static inline unsigned int __cq_get_elem_count(struct circular_queue *cq) { return (cq->rear - cq->front) & CQ_MASK; } static inline void mark_lock_accessed(struct lock_list *lock, struct lock_list *parent) { unsigned long nr; nr = lock - list_entries; WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */ lock->parent = parent; lock->class->dep_gen_id = lockdep_dependency_gen_id; } static inline unsigned long lock_accessed(struct lock_list *lock) { unsigned long nr; nr = lock - list_entries; WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */ return lock->class->dep_gen_id == lockdep_dependency_gen_id; } static inline struct lock_list *get_lock_parent(struct lock_list *child) { return child->parent; } static inline int get_lock_depth(struct lock_list *child) { int depth = 0; struct lock_list *parent; while ((parent = get_lock_parent(child))) { child = parent; depth++; } return depth; } static int __bfs(struct lock_list *source_entry, void *data, int (*match)(struct lock_list *entry, void *data), struct lock_list **target_entry, int forward) { struct lock_list *entry; struct list_head *head; struct circular_queue *cq = &lock_cq; int ret = 1; if (match(source_entry, data)) { *target_entry = source_entry; ret = 0; goto exit; } if (forward) head = &source_entry->class->locks_after; else head = &source_entry->class->locks_before; if (list_empty(head)) goto exit; __cq_init(cq); __cq_enqueue(cq, (unsigned long)source_entry); while (!__cq_empty(cq)) { struct lock_list *lock; __cq_dequeue(cq, (unsigned long *)&lock); if (!lock->class) { ret = -2; goto exit; } if (forward) head = &lock->class->locks_after; else head = &lock->class->locks_before; DEBUG_LOCKS_WARN_ON(!irqs_disabled()); list_for_each_entry_rcu(entry, head, entry) { if (!lock_accessed(entry)) { unsigned int cq_depth; mark_lock_accessed(entry, lock); if (match(entry, data)) { *target_entry = entry; ret = 0; goto exit; } if (__cq_enqueue(cq, (unsigned long)entry)) { ret = -1; goto exit; } cq_depth = __cq_get_elem_count(cq); if (max_bfs_queue_depth < cq_depth) max_bfs_queue_depth = cq_depth; } } } exit: return ret; } static inline int __bfs_forwards(struct lock_list *src_entry, void *data, int (*match)(struct lock_list *entry, void *data), struct lock_list **target_entry) { return __bfs(src_entry, data, match, target_entry, 1); } static inline int __bfs_backwards(struct lock_list *src_entry, void *data, int (*match)(struct lock_list *entry, void *data), struct lock_list **target_entry) { return __bfs(src_entry, data, match, target_entry, 0); } /* * Recursive, forwards-direction lock-dependency checking, used for * both noncyclic checking and for hardirq-unsafe/softirq-unsafe * checking. */ /* * Print a dependency chain entry (this is only done when a deadlock * has been detected): */ static noinline int print_circular_bug_entry(struct lock_list *target, int depth) { if (debug_locks_silent) return 0; printk("\n-> #%u", depth); print_lock_name(target->class); printk(KERN_CONT ":\n"); print_stack_trace(&target->trace, 6); return 0; } static void print_circular_lock_scenario(struct held_lock *src, struct held_lock *tgt, struct lock_list *prt) { struct lock_class *source = hlock_class(src); struct lock_class *target = hlock_class(tgt); struct lock_class *parent = prt->class; /* * A direct locking problem where unsafe_class lock is taken * directly by safe_class lock, then all we need to show * is the deadlock scenario, as it is obvious that the * unsafe lock is taken under the safe lock. * * But if there is a chain instead, where the safe lock takes * an intermediate lock (middle_class) where this lock is * not the same as the safe lock, then the lock chain is * used to describe the problem. Otherwise we would need * to show a different CPU case for each link in the chain * from the safe_class lock to the unsafe_class lock. */ if (parent != source) { printk("Chain exists of:\n "); __print_lock_name(source); printk(KERN_CONT " --> "); __print_lock_name(parent); printk(KERN_CONT " --> "); __print_lock_name(target); printk(KERN_CONT "\n\n"); } printk(" Possible unsafe locking scenario:\n\n"); printk(" CPU0 CPU1\n"); printk(" ---- ----\n"); printk(" lock("); __print_lock_name(target); printk(KERN_CONT ");\n"); printk(" lock("); __print_lock_name(parent); printk(KERN_CONT ");\n"); printk(" lock("); __print_lock_name(target); printk(KERN_CONT ");\n"); printk(" lock("); __print_lock_name(source); printk(KERN_CONT ");\n"); printk("\n *** DEADLOCK ***\n\n"); } /* * When a circular dependency is detected, print the * header first: */ static noinline int print_circular_bug_header(struct lock_list *entry, unsigned int depth, struct held_lock *check_src, struct held_lock *check_tgt) { struct task_struct *curr = current; if (debug_locks_silent) return 0; pr_warn("\n"); pr_warn("======================================================\n"); pr_warn("WARNING: possible circular locking dependency detected\n"); print_kernel_ident(); pr_warn("------------------------------------------------------\n"); pr_warn("%s/%d is trying to acquire lock:\n", curr->comm, task_pid_nr(curr)); print_lock(check_src); pr_warn("\nbut task is already holding lock:\n"); print_lock(check_tgt); pr_warn("\nwhich lock already depends on the new lock.\n\n"); pr_warn("\nthe existing dependency chain (in reverse order) is:\n"); print_circular_bug_entry(entry, depth); return 0; } static inline int class_equal(struct lock_list *entry, void *data) { return entry->class == data; } static noinline int print_circular_bug(struct lock_list *this, struct lock_list *target, struct held_lock *check_src, struct held_lock *check_tgt, struct stack_trace *trace) { struct task_struct *curr = current; struct lock_list *parent; struct lock_list *first_parent; int depth; if (!debug_locks_off_graph_unlock() || debug_locks_silent) return 0; if (!save_trace(&this->trace)) return 0; depth = get_lock_depth(target); print_circular_bug_header(target, depth, check_src, check_tgt); parent = get_lock_parent(target); first_parent = parent; while (parent) { print_circular_bug_entry(parent, --depth); parent = get_lock_parent(parent); } printk("\nother info that might help us debug this:\n\n"); print_circular_lock_scenario(check_src, check_tgt, first_parent); lockdep_print_held_locks(curr); printk("\nstack backtrace:\n"); dump_stack(); return 0; } static noinline int print_bfs_bug(int ret) { if (!debug_locks_off_graph_unlock()) return 0; /* * Breadth-first-search failed, graph got corrupted? */ WARN(1, "lockdep bfs error:%d\n", ret); return 0; } static int noop_count(struct lock_list *entry, void *data) { (*(unsigned long *)data)++; return 0; } static unsigned long __lockdep_count_forward_deps(struct lock_list *this) { unsigned long count = 0; struct lock_list *uninitialized_var(target_entry); __bfs_forwards(this, (void *)&count, noop_count, &target_entry); return count; } unsigned long lockdep_count_forward_deps(struct lock_class *class) { unsigned long ret, flags; struct lock_list this; this.parent = NULL; this.class = class; raw_local_irq_save(flags); arch_spin_lock(&lockdep_lock); ret = __lockdep_count_forward_deps(&this); arch_spin_unlock(&lockdep_lock); raw_local_irq_restore(flags); return ret; } static unsigned long __lockdep_count_backward_deps(struct lock_list *this) { unsigned long count = 0; struct lock_list *uninitialized_var(target_entry); __bfs_backwards(this, (void *)&count, noop_count, &target_entry); return count; } unsigned long lockdep_count_backward_deps(struct lock_class *class) { unsigned long ret, flags; struct lock_list this; this.parent = NULL; this.class = class; raw_local_irq_save(flags); arch_spin_lock(&lockdep_lock); ret = __lockdep_count_backward_deps(&this); arch_spin_unlock(&lockdep_lock); raw_local_irq_restore(flags); return ret; } /* * Prove that the dependency graph starting at <entry> can not * lead to <target>. Print an error and return 0 if it does. */ static noinline int check_noncircular(struct lock_list *root, struct lock_class *target, struct lock_list **target_entry) { int result; debug_atomic_inc(nr_cyclic_checks); result = __bfs_forwards(root, target, class_equal, target_entry); return result; } static noinline int check_redundant(struct lock_list *root, struct lock_class *target, struct lock_list **target_entry) { int result; debug_atomic_inc(nr_redundant_checks); result = __bfs_forwards(root, target, class_equal, target_entry); return result; } #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) /* * Forwards and backwards subgraph searching, for the purposes of * proving that two subgraphs can be connected by a new dependency * without creating any illegal irq-safe -> irq-unsafe lock dependency. */ static inline int usage_match(struct lock_list *entry, void *bit) { return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit); } /* * Find a node in the forwards-direction dependency sub-graph starting * at @root->class that matches @bit. * * Return 0 if such a node exists in the subgraph, and put that node * into *@target_entry. * * Return 1 otherwise and keep *@target_entry unchanged. * Return <0 on error. */ static int find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit, struct lock_list **target_entry) { int result; debug_atomic_inc(nr_find_usage_forwards_checks); result = __bfs_forwards(root, (void *)bit, usage_match, target_entry); return result; } /* * Find a node in the backwards-direction dependency sub-graph starting * at @root->class that matches @bit. * * Return 0 if such a node exists in the subgraph, and put that node * into *@target_entry. * * Return 1 otherwise and keep *@target_entry unchanged. * Return <0 on error. */ static int find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit, struct lock_list **target_entry) { int result; debug_atomic_inc(nr_find_usage_backwards_checks); result = __bfs_backwards(root, (void *)bit, usage_match, target_entry); return result; } static void print_lock_class_header(struct lock_class *class, int depth) { int bit; printk("%*s->", depth, ""); print_lock_name(class); #ifdef CONFIG_DEBUG_LOCKDEP printk(KERN_CONT " ops: %lu", debug_class_ops_read(class)); #endif printk(KERN_CONT " {\n"); for (bit = 0; bit < LOCK_USAGE_STATES; bit++) { if (class->usage_mask & (1 << bit)) { int len = depth; len += printk("%*s %s", depth, "", usage_str[bit]); len += printk(KERN_CONT " at:\n"); print_stack_trace(class->usage_traces + bit, len); } } printk("%*s }\n", depth, ""); printk("%*s ... key at: [<%px>] %pS\n", depth, "", class->key, class->key); } /* * printk the shortest lock dependencies from @start to @end in reverse order: */ static void __used print_shortest_lock_dependencies(struct lock_list *leaf, struct lock_list *root) { struct lock_list *entry = leaf; int depth; /*compute depth from generated tree by BFS*/ depth = get_lock_depth(leaf); do { print_lock_class_header(entry->class, depth); printk("%*s ... acquired at:\n", depth, ""); print_stack_trace(&entry->trace, 2); printk("\n"); if (depth == 0 && (entry != root)) { printk("lockdep:%s bad path found in chain graph\n", __func__); break; } entry = get_lock_parent(entry); depth--; } while (entry && (depth >= 0)); return; } static void print_irq_lock_scenario(struct lock_list *safe_entry, struct lock_list *unsafe_entry, struct lock_class *prev_class, struct lock_class *next_class) { struct lock_class *safe_class = safe_entry->class; struct lock_class *unsafe_class = unsafe_entry->class; struct lock_class *middle_class = prev_class; if (middle_class == safe_class) middle_class = next_class; /* * A direct locking problem where unsafe_class lock is taken * directly by safe_class lock, then all we need to show * is the deadlock scenario, as it is obvious that the * unsafe lock is taken under the safe lock. * * But if there is a chain instead, where the safe lock takes * an intermediate lock (middle_class) where this lock is * not the same as the safe lock, then the lock chain is * used to describe the problem. Otherwise we would need * to show a different CPU case for each link in the chain * from the safe_class lock to the unsafe_class lock. */ if (middle_class != unsafe_class) { printk("Chain exists of:\n "); __print_lock_name(safe_class); printk(KERN_CONT " --> "); __print_lock_name(middle_class); printk(KERN_CONT " --> "); __print_lock_name(unsafe_class); printk(KERN_CONT "\n\n"); } printk(" Possible interrupt unsafe locking scenario:\n\n"); printk(" CPU0 CPU1\n"); printk(" ---- ----\n"); printk(" lock("); __print_lock_name(unsafe_class); printk(KERN_CONT ");\n"); printk(" local_irq_disable();\n"); printk(" lock("); __print_lock_name(safe_class); printk(KERN_CONT ");\n"); printk(" lock("); __print_lock_name(middle_class); printk(KERN_CONT ");\n"); printk(" <Interrupt>\n"); printk(" lock("); __print_lock_name(safe_class); printk(KERN_CONT ");\n"); printk("\n *** DEADLOCK ***\n\n"); } static int print_bad_irq_dependency(struct task_struct *curr, struct lock_list *prev_root, struct lock_list *next_root, struct lock_list *backwards_entry, struct lock_list *forwards_entry, struct held_lock *prev, struct held_lock *next, enum lock_usage_bit bit1, enum lock_usage_bit bit2, const char *irqclass) { if (!debug_locks_off_graph_unlock() || debug_locks_silent) return 0; pr_warn("\n"); pr_warn("=====================================================\n"); pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n", irqclass, irqclass); print_kernel_ident(); pr_warn("-----------------------------------------------------\n"); pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n", curr->comm, task_pid_nr(curr), curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT, curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT, curr->hardirqs_enabled, curr->softirqs_enabled); print_lock(next); pr_warn("\nand this task is already holding:\n"); print_lock(prev); pr_warn("which would create a new lock dependency:\n"); print_lock_name(hlock_class(prev)); pr_cont(" ->"); print_lock_name(hlock_class(next)); pr_cont("\n"); pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n", irqclass); print_lock_name(backwards_entry->class); pr_warn("\n... which became %s-irq-safe at:\n", irqclass); print_stack_trace(backwards_entry->class->usage_traces + bit1, 1); pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass); print_lock_name(forwards_entry->class); pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass); pr_warn("..."); print_stack_trace(forwards_entry->class->usage_traces + bit2, 1); pr_warn("\nother info that might help us debug this:\n\n"); print_irq_lock_scenario(backwards_entry, forwards_entry, hlock_class(prev), hlock_class(next)); lockdep_print_held_locks(curr); pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass); if (!save_trace(&prev_root->trace)) return 0; print_shortest_lock_dependencies(backwards_entry, prev_root); pr_warn("\nthe dependencies between the lock to be acquired"); pr_warn(" and %s-irq-unsafe lock:\n", irqclass); if (!save_trace(&next_root->trace)) return 0; print_shortest_lock_dependencies(forwards_entry, next_root); pr_warn("\nstack backtrace:\n"); dump_stack(); return 0; } static int check_usage(struct task_struct *curr, struct held_lock *prev, struct held_lock *next, enum lock_usage_bit bit_backwards, enum lock_usage_bit bit_forwards, const char *irqclass) { int ret; struct lock_list this, that; struct lock_list *uninitialized_var(target_entry); struct lock_list *uninitialized_var(target_entry1); this.parent = NULL; this.class = hlock_class(prev); ret = find_usage_backwards(&this, bit_backwards, &target_entry); if (ret < 0) return print_bfs_bug(ret); if (ret == 1) return ret; that.parent = NULL; that.class = hlock_class(next); ret = find_usage_forwards(&that, bit_forwards, &target_entry1); if (ret < 0) return print_bfs_bug(ret); if (ret == 1) return ret; return print_bad_irq_dependency(curr, &this, &that, target_entry, target_entry1, prev, next, bit_backwards, bit_forwards, irqclass); } static const char *state_names[] = { #define LOCKDEP_STATE(__STATE) \ __stringify(__STATE), #include "lockdep_states.h" #undef LOCKDEP_STATE }; static const char *state_rnames[] = { #define LOCKDEP_STATE(__STATE) \ __stringify(__STATE)"-READ", #include "lockdep_states.h" #undef LOCKDEP_STATE }; static inline const char *state_name(enum lock_usage_bit bit) { return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2]; } static int exclusive_bit(int new_bit) { /* * USED_IN * USED_IN_READ * ENABLED * ENABLED_READ * * bit 0 - write/read * bit 1 - used_in/enabled * bit 2+ state */ int state = new_bit & ~3; int dir = new_bit & 2; /* * keep state, bit flip the direction and strip read. */ return state | (dir ^ 2); } static int check_irq_usage(struct task_struct *curr, struct held_lock *prev, struct held_lock *next, enum lock_usage_bit bit) { /* * Prove that the new dependency does not connect a hardirq-safe * lock with a hardirq-unsafe lock - to achieve this we search * the backwards-subgraph starting at <prev>, and the * forwards-subgraph starting at <next>: */ if (!check_usage(curr, prev, next, bit, exclusive_bit(bit), state_name(bit))) return 0; bit++; /* _READ */ /* * Prove that the new dependency does not connect a hardirq-safe-read * lock with a hardirq-unsafe lock - to achieve this we search * the backwards-subgraph starting at <prev>, and the * forwards-subgraph starting at <next>: */ if (!check_usage(curr, prev, next, bit, exclusive_bit(bit), state_name(bit))) return 0; return 1; } static int check_prev_add_irq(struct task_struct *curr, struct held_lock *prev, struct held_lock *next) { #define LOCKDEP_STATE(__STATE) \ if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \ return 0; #include "lockdep_states.h" #undef LOCKDEP_STATE return 1; } static void inc_chains(void) { if (current->hardirq_context) nr_hardirq_chains++; else { if (current->softirq_context) nr_softirq_chains++; else nr_process_chains++; } } #else static inline int check_prev_add_irq(struct task_struct *curr, struct held_lock *prev, struct held_lock *next) { return 1; } static inline void inc_chains(void) { nr_process_chains++; } #endif static void print_deadlock_scenario(struct held_lock *nxt, struct held_lock *prv) { struct lock_class *next = hlock_class(nxt); struct lock_class *prev = hlock_class(prv); printk(" Possible unsafe locking scenario:\n\n"); printk(" CPU0\n"); printk(" ----\n"); printk(" lock("); __print_lock_name(prev); printk(KERN_CONT ");\n"); printk(" lock("); __print_lock_name(next); printk(KERN_CONT ");\n"); printk("\n *** DEADLOCK ***\n\n"); printk(" May be due to missing lock nesting notation\n\n"); } static int print_deadlock_bug(struct task_struct *curr, struct held_lock *prev, struct held_lock *next) { if (!debug_locks_off_graph_unlock() || debug_locks_silent) return 0; pr_warn("\n"); pr_warn("============================================\n"); pr_warn("WARNING: possible recursive locking detected\n"); print_kernel_ident(); pr_warn("--------------------------------------------\n"); pr_warn("%s/%d is trying to acquire lock:\n", curr->comm, task_pid_nr(curr)); print_lock(next); pr_warn("\nbut task is already holding lock:\n"); print_lock(prev); pr_warn("\nother info that might help us debug this:\n"); print_deadlock_scenario(next, prev); lockdep_print_held_locks(curr); pr_warn("\nstack backtrace:\n"); dump_stack(); return 0; } /* * Check whether we are holding such a class already. * * (Note that this has to be done separately, because the graph cannot * detect such classes of deadlocks.) * * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read */ static int check_deadlock(struct task_struct *curr, struct held_lock *next, struct lockdep_map *next_instance, int read) { struct held_lock *prev; struct held_lock *nest = NULL; int i; for (i = 0; i < curr->lockdep_depth; i++) { prev = curr->held_locks + i; if (prev->instance == next->nest_lock) nest = prev; if (hlock_class(prev) != hlock_class(next)) continue; /* * Allow read-after-read recursion of the same * lock class (i.e. read_lock(lock)+read_lock(lock)): */ if ((read == 2) && prev->read) return 2; /* * We're holding the nest_lock, which serializes this lock's * nesting behaviour. */ if (nest) return 2; return print_deadlock_bug(curr, prev, next); } return 1; } /* * There was a chain-cache miss, and we are about to add a new dependency * to a previous lock. We recursively validate the following rules: * * - would the adding of the <prev> -> <next> dependency create a * circular dependency in the graph? [== circular deadlock] * * - does the new prev->next dependency connect any hardirq-safe lock * (in the full backwards-subgraph starting at <prev>) with any * hardirq-unsafe lock (in the full forwards-subgraph starting at * <next>)? [== illegal lock inversion with hardirq contexts] * * - does the new prev->next dependency connect any softirq-safe lock * (in the full backwards-subgraph starting at <prev>) with any * softirq-unsafe lock (in the full forwards-subgraph starting at * <next>)? [== illegal lock inversion with softirq contexts] * * any of these scenarios could lead to a deadlock. * * Then if all the validations pass, we add the forwards and backwards * dependency. */ static int check_prev_add(struct task_struct *curr, struct held_lock *prev, struct held_lock *next, int distance, struct stack_trace *trace, int (*save)(struct stack_trace *trace)) { struct lock_list *uninitialized_var(target_entry); struct lock_list *entry; struct lock_list this; int ret; /* * Prove that the new <prev> -> <next> dependency would not * create a circular dependency in the graph. (We do this by * forward-recursing into the graph starting at <next>, and * checking whether we can reach <prev>.) * * We are using global variables to control the recursion, to * keep the stackframe size of the recursive functions low: */ this.class = hlock_class(next); this.parent = NULL; ret = check_noncircular(&this, hlock_class(prev), &target_entry); if (unlikely(!ret)) { if (!trace->entries) { /* * If @save fails here, the printing might trigger * a WARN but because of the !nr_entries it should * not do bad things. */ save(trace); } return print_circular_bug(&this, target_entry, next, prev, trace); } else if (unlikely(ret < 0)) return print_bfs_bug(ret); if (!check_prev_add_irq(curr, prev, next)) return 0; /* * For recursive read-locks we do all the dependency checks, * but we dont store read-triggered dependencies (only * write-triggered dependencies). This ensures that only the * write-side dependencies matter, and that if for example a * write-lock never takes any other locks, then the reads are * equivalent to a NOP. */ if (next->read == 2 || prev->read == 2) return 1; /* * Is the <prev> -> <next> dependency already present? * * (this may occur even though this is a new chain: consider * e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3 * chains - the second one will be new, but L1 already has * L2 added to its dependency list, due to the first chain.) */ list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) { if (entry->class == hlock_class(next)) { if (distance == 1) entry->distance = 1; return 1; } } /* * Is the <prev> -> <next> link redundant? */ this.class = hlock_class(prev); this.parent = NULL; ret = check_redundant(&this, hlock_class(next), &target_entry); if (!ret) { debug_atomic_inc(nr_redundant); return 2; } if (ret < 0) return print_bfs_bug(ret); if (!trace->entries && !save(trace)) return 0; /* * Ok, all validations passed, add the new lock * to the previous lock's dependency list: */ ret = add_lock_to_list(hlock_class(next), &hlock_class(prev)->locks_after, next->acquire_ip, distance, trace); if (!ret) return 0; ret = add_lock_to_list(hlock_class(prev), &hlock_class(next)->locks_before, next->acquire_ip, distance, trace); if (!ret) return 0; return 2; } /* * Add the dependency to all directly-previous locks that are 'relevant'. * The ones that are relevant are (in increasing distance from curr): * all consecutive trylock entries and the final non-trylock entry - or * the end of this context's lock-chain - whichever comes first. */ static int check_prevs_add(struct task_struct *curr, struct held_lock *next) { int depth = curr->lockdep_depth; struct held_lock *hlock; struct stack_trace trace = { .nr_entries = 0, .max_entries = 0, .entries = NULL, .skip = 0, }; /* * Debugging checks. * * Depth must not be zero for a non-head lock: */ if (!depth) goto out_bug; /* * At least two relevant locks must exist for this * to be a head: */ if (curr->held_locks[depth].irq_context != curr->held_locks[depth-1].irq_context) goto out_bug; for (;;) { int distance = curr->lockdep_depth - depth + 1; hlock = curr->held_locks + depth - 1; /* * Only non-recursive-read entries get new dependencies * added: */ if (hlock->read != 2 && hlock->check) { int ret = check_prev_add(curr, hlock, next, distance, &trace, save_trace); if (!ret) return 0; /* * Stop after the first non-trylock entry, * as non-trylock entries have added their * own direct dependencies already, so this * lock is connected to them indirectly: */ if (!hlock->trylock) break; } depth--; /* * End of lock-stack? */ if (!depth) break; /* * Stop the search if we cross into another context: */ if (curr->held_locks[depth].irq_context != curr->held_locks[depth-1].irq_context) break; } return 1; out_bug: if (!debug_locks_off_graph_unlock()) return 0; /* * Clearly we all shouldn't be here, but since we made it we * can reliable say we messed up our state. See the above two * gotos for reasons why we could possibly end up here. */ WARN_ON(1); return 0; } unsigned long nr_lock_chains; struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS]; int nr_chain_hlocks; static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS]; struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i) { return lock_classes + chain_hlocks[chain->base + i]; } /* * Returns the index of the first held_lock of the current chain */ static inline int get_first_held_lock(struct task_struct *curr, struct held_lock *hlock) { int i; struct held_lock *hlock_curr; for (i = curr->lockdep_depth - 1; i >= 0; i--) { hlock_curr = curr->held_locks + i; if (hlock_curr->irq_context != hlock->irq_context) break; } return ++i; } #ifdef CONFIG_DEBUG_LOCKDEP /* * Returns the next chain_key iteration */ static u64 print_chain_key_iteration(int class_idx, u64 chain_key) { u64 new_chain_key = iterate_chain_key(chain_key, class_idx); printk(" class_idx:%d -> chain_key:%016Lx", class_idx, (unsigned long long)new_chain_key); return new_chain_key; } static void print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next) { struct held_lock *hlock; u64 chain_key = 0; int depth = curr->lockdep_depth; int i; printk("depth: %u\n", depth + 1); for (i = get_first_held_lock(curr, hlock_next); i < depth; i++) { hlock = curr->held_locks + i; chain_key = print_chain_key_iteration(hlock->class_idx, chain_key); print_lock(hlock); } print_chain_key_iteration(hlock_next->class_idx, chain_key); print_lock(hlock_next); } static void print_chain_keys_chain(struct lock_chain *chain) { int i; u64 chain_key = 0; int class_id; printk("depth: %u\n", chain->depth); for (i = 0; i < chain->depth; i++) { class_id = chain_hlocks[chain->base + i]; chain_key = print_chain_key_iteration(class_id + 1, chain_key); print_lock_name(lock_classes + class_id); printk("\n"); } } static void print_collision(struct task_struct *curr, struct held_lock *hlock_next, struct lock_chain *chain) { pr_warn("\n"); pr_warn("============================\n"); pr_warn("WARNING: chain_key collision\n"); print_kernel_ident(); pr_warn("----------------------------\n"); pr_warn("%s/%d: ", current->comm, task_pid_nr(current)); pr_warn("Hash chain already cached but the contents don't match!\n"); pr_warn("Held locks:"); print_chain_keys_held_locks(curr, hlock_next); pr_warn("Locks in cached chain:"); print_chain_keys_chain(chain); pr_warn("\nstack backtrace:\n"); dump_stack(); } #endif /* * Checks whether the chain and the current held locks are consistent * in depth and also in content. If they are not it most likely means * that there was a collision during the calculation of the chain_key. * Returns: 0 not passed, 1 passed */ static int check_no_collision(struct task_struct *curr, struct held_lock *hlock, struct lock_chain *chain) { #ifdef CONFIG_DEBUG_LOCKDEP int i, j, id; i = get_first_held_lock(curr, hlock); if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) { print_collision(curr, hlock, chain); return 0; } for (j = 0; j < chain->depth - 1; j++, i++) { id = curr->held_locks[i].class_idx - 1; if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) { print_collision(curr, hlock, chain); return 0; } } #endif return 1; } /* * Adds a dependency chain into chain hashtable. And must be called with * graph_lock held. * * Return 0 if fail, and graph_lock is released. * Return 1 if succeed, with graph_lock held. */ static inline int add_chain_cache(struct task_struct *curr, struct held_lock *hlock, u64 chain_key) { struct lock_class *class = hlock_class(hlock); struct hlist_head *hash_head = chainhashentry(chain_key); struct lock_chain *chain; int i, j; /* * Allocate a new chain entry from the static array, and add * it to the hash: */ /* * We might need to take the graph lock, ensure we've got IRQs * disabled to make this an IRQ-safe lock.. for recursion reasons * lockdep won't complain about its own locking errors. */ if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) return 0; if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) { if (!debug_locks_off_graph_unlock()) return 0; print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!"); dump_stack(); return 0; } chain = lock_chains + nr_lock_chains++; chain->chain_key = chain_key; chain->irq_context = hlock->irq_context; i = get_first_held_lock(curr, hlock); chain->depth = curr->lockdep_depth + 1 - i; BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks)); BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr->held_locks)); BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes)); if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) { chain->base = nr_chain_hlocks; for (j = 0; j < chain->depth - 1; j++, i++) { int lock_id = curr->held_locks[i].class_idx - 1; chain_hlocks[chain->base + j] = lock_id; } chain_hlocks[chain->base + j] = class - lock_classes; } if (nr_chain_hlocks < MAX_LOCKDEP_CHAIN_HLOCKS) nr_chain_hlocks += chain->depth; #ifdef CONFIG_DEBUG_LOCKDEP /* * Important for check_no_collision(). */ if (unlikely(nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)) { if (!debug_locks_off_graph_unlock()) return 0; print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!"); dump_stack(); return 0; } #endif hlist_add_head_rcu(&chain->entry, hash_head); debug_atomic_inc(chain_lookup_misses); inc_chains(); return 1; } /* * Look up a dependency chain. */ static inline struct lock_chain *lookup_chain_cache(u64 chain_key) { struct hlist_head *hash_head = chainhashentry(chain_key); struct lock_chain *chain; /* * We can walk it lock-free, because entries only get added * to the hash: */ hlist_for_each_entry_rcu(chain, hash_head, entry) { if (chain->chain_key == chain_key) { debug_atomic_inc(chain_lookup_hits); return chain; } } return NULL; } /* * If the key is not present yet in dependency chain cache then * add it and return 1 - in this case the new dependency chain is * validated. If the key is already hashed, return 0. * (On return with 1 graph_lock is held.) */ static inline int lookup_chain_cache_add(struct task_struct *curr, struct held_lock *hlock, u64 chain_key) { struct lock_class *class = hlock_class(hlock); struct lock_chain *chain = lookup_chain_cache(chain_key); if (chain) { cache_hit: if (!check_no_collision(curr, hlock, chain)) return 0; if (very_verbose(class)) { printk("\nhash chain already cached, key: " "%016Lx tail class: [%px] %s\n", (unsigned long long)chain_key, class->key, class->name); } return 0; } if (very_verbose(class)) { printk("\nnew hash chain, key: %016Lx tail class: [%px] %s\n", (unsigned long long)chain_key, class->key, class->name); } if (!graph_lock()) return 0; /* * We have to walk the chain again locked - to avoid duplicates: */ chain = lookup_chain_cache(chain_key); if (chain) { graph_unlock(); goto cache_hit; } if (!add_chain_cache(curr, hlock, chain_key)) return 0; return 1; } static int validate_chain(struct task_struct *curr, struct lockdep_map *lock, struct held_lock *hlock, int chain_head, u64 chain_key) { /* * Trylock needs to maintain the stack of held locks, but it * does not add new dependencies, because trylock can be done * in any order. * * We look up the chain_key and do the O(N^2) check and update of * the dependencies only if this is a new dependency chain. * (If lookup_chain_cache_add() return with 1 it acquires * graph_lock for us) */ if (!hlock->trylock && hlock->check && lookup_chain_cache_add(curr, hlock, chain_key)) { /* * Check whether last held lock: * * - is irq-safe, if this lock is irq-unsafe * - is softirq-safe, if this lock is hardirq-unsafe * * And check whether the new lock's dependency graph * could lead back to the previous lock. * * any of these scenarios could lead to a deadlock. If * All validations */ int ret = check_deadlock(curr, hlock, lock, hlock->read); if (!ret) return 0; /* * Mark recursive read, as we jump over it when * building dependencies (just like we jump over * trylock entries): */ if (ret == 2) hlock->read = 2; /* * Add dependency only if this lock is not the head * of the chain, and if it's not a secondary read-lock: */ if (!chain_head && ret != 2) { if (!check_prevs_add(curr, hlock)) return 0; } graph_unlock(); } else { /* after lookup_chain_cache_add(): */ if (unlikely(!debug_locks)) return 0; } return 1; } #else static inline int validate_chain(struct task_struct *curr, struct lockdep_map *lock, struct held_lock *hlock, int chain_head, u64 chain_key) { return 1; } #endif /* * We are building curr_chain_key incrementally, so double-check * it from scratch, to make sure that it's done correctly: */ static void check_chain_key(struct task_struct *curr) { #ifdef CONFIG_DEBUG_LOCKDEP struct held_lock *hlock, *prev_hlock = NULL; unsigned int i; u64 chain_key = 0; for (i = 0; i < curr->lockdep_depth; i++) { hlock = curr->held_locks + i; if (chain_key != hlock->prev_chain_key) { debug_locks_off(); /* * We got mighty confused, our chain keys don't match * with what we expect, someone trample on our task state? */ WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n", curr->lockdep_depth, i, (unsigned long long)chain_key, (unsigned long long)hlock->prev_chain_key); return; } /* * Whoops ran out of static storage again? */ if (DEBUG_LOCKS_WARN_ON(hlock->class_idx > MAX_LOCKDEP_KEYS)) return; if (prev_hlock && (prev_hlock->irq_context != hlock->irq_context)) chain_key = 0; chain_key = iterate_chain_key(chain_key, hlock->class_idx); prev_hlock = hlock; } if (chain_key != curr->curr_chain_key) { debug_locks_off(); /* * More smoking hash instead of calculating it, damn see these * numbers float.. I bet that a pink elephant stepped on my memory. */ WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n", curr->lockdep_depth, i, (unsigned long long)chain_key, (unsigned long long)curr->curr_chain_key); } #endif } static void print_usage_bug_scenario(struct held_lock *lock) { struct lock_class *class = hlock_class(lock); printk(" Possible unsafe locking scenario:\n\n"); printk(" CPU0\n"); printk(" ----\n"); printk(" lock("); __print_lock_name(class); printk(KERN_CONT ");\n"); printk(" <Interrupt>\n"); printk(" lock("); __print_lock_name(class); printk(KERN_CONT ");\n"); printk("\n *** DEADLOCK ***\n\n"); } static int print_usage_bug(struct task_struct *curr, struct held_lock *this, enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit) { if (!debug_locks_off_graph_unlock() || debug_locks_silent) return 0; pr_warn("\n"); pr_warn("================================\n"); pr_warn("WARNING: inconsistent lock state\n"); print_kernel_ident(); pr_warn("--------------------------------\n"); pr_warn("inconsistent {%s} -> {%s} usage.\n", usage_str[prev_bit], usage_str[new_bit]); pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n", curr->comm, task_pid_nr(curr), trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT, trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT, trace_hardirqs_enabled(curr), trace_softirqs_enabled(curr)); print_lock(this); pr_warn("{%s} state was registered at:\n", usage_str[prev_bit]); print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1); print_irqtrace_events(curr); pr_warn("\nother info that might help us debug this:\n"); print_usage_bug_scenario(this); lockdep_print_held_locks(curr); pr_warn("\nstack backtrace:\n"); dump_stack(); return 0; } /* * Print out an error if an invalid bit is set: */ static inline int valid_state(struct task_struct *curr, struct held_lock *this, enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit) { if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit))) return print_usage_bug(curr, this, bad_bit, new_bit); return 1; } static int mark_lock(struct task_struct *curr, struct held_lock *this, enum lock_usage_bit new_bit); #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) /* * print irq inversion bug: */ static int print_irq_inversion_bug(struct task_struct *curr, struct lock_list *root, struct lock_list *other, struct held_lock *this, int forwards, const char *irqclass) { struct lock_list *entry = other; struct lock_list *middle = NULL; int depth; if (!debug_locks_off_graph_unlock() || debug_locks_silent) return 0; pr_warn("\n"); pr_warn("========================================================\n"); pr_warn("WARNING: possible irq lock inversion dependency detected\n"); print_kernel_ident(); pr_warn("--------------------------------------------------------\n"); pr_warn("%s/%d just changed the state of lock:\n", curr->comm, task_pid_nr(curr)); print_lock(this); if (forwards) pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass); else pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass); print_lock_name(other->class); pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n"); pr_warn("\nother info that might help us debug this:\n"); /* Find a middle lock (if one exists) */ depth = get_lock_depth(other); do { if (depth == 0 && (entry != root)) { pr_warn("lockdep:%s bad path found in chain graph\n", __func__); break; } middle = entry; entry = get_lock_parent(entry); depth--; } while (entry && entry != root && (depth >= 0)); if (forwards) print_irq_lock_scenario(root, other, middle ? middle->class : root->class, other->class); else print_irq_lock_scenario(other, root, middle ? middle->class : other->class, root->class); lockdep_print_held_locks(curr); pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n"); if (!save_trace(&root->trace)) return 0; print_shortest_lock_dependencies(other, root); pr_warn("\nstack backtrace:\n"); dump_stack(); return 0; } /* * Prove that in the forwards-direction subgraph starting at <this> * there is no lock matching <mask>: */ static int check_usage_forwards(struct task_struct *curr, struct held_lock *this, enum lock_usage_bit bit, const char *irqclass) { int ret; struct lock_list root; struct lock_list *uninitialized_var(target_entry); root.parent = NULL; root.class = hlock_class(this); ret = find_usage_forwards(&root, bit, &target_entry); if (ret < 0) return print_bfs_bug(ret); if (ret == 1) return ret; return print_irq_inversion_bug(curr, &root, target_entry, this, 1, irqclass); } /* * Prove that in the backwards-direction subgraph starting at <this> * there is no lock matching <mask>: */ static int check_usage_backwards(struct task_struct *curr, struct held_lock *this, enum lock_usage_bit bit, const char *irqclass) { int ret; struct lock_list root; struct lock_list *uninitialized_var(target_entry); root.parent = NULL; root.class = hlock_class(this); ret = find_usage_backwards(&root, bit, &target_entry); if (ret < 0) return print_bfs_bug(ret); if (ret == 1) return ret; return print_irq_inversion_bug(curr, &root, target_entry, this, 0, irqclass); } void print_irqtrace_events(struct task_struct *curr) { printk("irq event stamp: %u\n", curr->irq_events); printk("hardirqs last enabled at (%u): [<%px>] %pS\n", curr->hardirq_enable_event, (void *)curr->hardirq_enable_ip, (void *)curr->hardirq_enable_ip); printk("hardirqs last disabled at (%u): [<%px>] %pS\n", curr->hardirq_disable_event, (void *)curr->hardirq_disable_ip, (void *)curr->hardirq_disable_ip); printk("softirqs last enabled at (%u): [<%px>] %pS\n", curr->softirq_enable_event, (void *)curr->softirq_enable_ip, (void *)curr->softirq_enable_ip); printk("softirqs last disabled at (%u): [<%px>] %pS\n", curr->softirq_disable_event, (void *)curr->softirq_disable_ip, (void *)curr->softirq_disable_ip); } static int HARDIRQ_verbose(struct lock_class *class) { #if HARDIRQ_VERBOSE return class_filter(class); #endif return 0; } static int SOFTIRQ_verbose(struct lock_class *class) { #if SOFTIRQ_VERBOSE return class_filter(class); #endif return 0; } #define STRICT_READ_CHECKS 1 static int (*state_verbose_f[])(struct lock_class *class) = { #define LOCKDEP_STATE(__STATE) \ __STATE##_verbose, #include "lockdep_states.h" #undef LOCKDEP_STATE }; static inline int state_verbose(enum lock_usage_bit bit, struct lock_class *class) { return state_verbose_f[bit >> 2](class); } typedef int (*check_usage_f)(struct task_struct *, struct held_lock *, enum lock_usage_bit bit, const char *name); static int mark_lock_irq(struct task_struct *curr, struct held_lock *this, enum lock_usage_bit new_bit) { int excl_bit = exclusive_bit(new_bit); int read = new_bit & 1; int dir = new_bit & 2; /* * mark USED_IN has to look forwards -- to ensure no dependency * has ENABLED state, which would allow recursion deadlocks. * * mark ENABLED has to look backwards -- to ensure no dependee * has USED_IN state, which, again, would allow recursion deadlocks. */ check_usage_f usage = dir ? check_usage_backwards : check_usage_forwards; /* * Validate that this particular lock does not have conflicting * usage states. */ if (!valid_state(curr, this, new_bit, excl_bit)) return 0; /* * Validate that the lock dependencies don't have conflicting usage * states. */ if ((!read || !dir || STRICT_READ_CHECKS) && !usage(curr, this, excl_bit, state_name(new_bit & ~1))) return 0; /* * Check for read in write conflicts */ if (!read) { if (!valid_state(curr, this, new_bit, excl_bit + 1)) return 0; if (STRICT_READ_CHECKS && !usage(curr, this, excl_bit + 1, state_name(new_bit + 1))) return 0; } if (state_verbose(new_bit, hlock_class(this))) return 2; return 1; } enum mark_type { #define LOCKDEP_STATE(__STATE) __STATE, #include "lockdep_states.h" #undef LOCKDEP_STATE }; /* * Mark all held locks with a usage bit: */ static int mark_held_locks(struct task_struct *curr, enum mark_type mark) { enum lock_usage_bit usage_bit; struct held_lock *hlock; int i; for (i = 0; i < curr->lockdep_depth; i++) { hlock = curr->held_locks + i; usage_bit = 2 + (mark << 2); /* ENABLED */ if (hlock->read) usage_bit += 1; /* READ */ BUG_ON(usage_bit >= LOCK_USAGE_STATES); if (!hlock->check) continue; if (!mark_lock(curr, hlock, usage_bit)) return 0; } return 1; } /* * Hardirqs will be enabled: */ static void __trace_hardirqs_on_caller(unsigned long ip) { struct task_struct *curr = current; /* we'll do an OFF -> ON transition: */ curr->hardirqs_enabled = 1; /* * We are going to turn hardirqs on, so set the * usage bit for all held locks: */ if (!mark_held_locks(curr, HARDIRQ)) return; /* * If we have softirqs enabled, then set the usage * bit for all held locks. (disabled hardirqs prevented * this bit from being set before) */ if (curr->softirqs_enabled) if (!mark_held_locks(curr, SOFTIRQ)) return; curr->hardirq_enable_ip = ip; curr->hardirq_enable_event = ++curr->irq_events; debug_atomic_inc(hardirqs_on_events); } void lockdep_hardirqs_on(unsigned long ip) { if (unlikely(!debug_locks || current->lockdep_recursion)) return; if (unlikely(current->hardirqs_enabled)) { /* * Neither irq nor preemption are disabled here * so this is racy by nature but losing one hit * in a stat is not a big deal. */ __debug_atomic_inc(redundant_hardirqs_on); return; } /* * We're enabling irqs and according to our state above irqs weren't * already enabled, yet we find the hardware thinks they are in fact * enabled.. someone messed up their IRQ state tracing. */ if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) return; /* * See the fine text that goes along with this variable definition. */ if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled))) return; /* * Can't allow enabling interrupts while in an interrupt handler, * that's general bad form and such. Recursion, limited stack etc.. */ if (DEBUG_LOCKS_WARN_ON(current->hardirq_context)) return; current->lockdep_recursion = 1; __trace_hardirqs_on_caller(ip); current->lockdep_recursion = 0; } /* * Hardirqs were disabled: */ void lockdep_hardirqs_off(unsigned long ip) { struct task_struct *curr = current; if (unlikely(!debug_locks || current->lockdep_recursion)) return; /* * So we're supposed to get called after you mask local IRQs, but for * some reason the hardware doesn't quite think you did a proper job. */ if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) return; if (curr->hardirqs_enabled) { /* * We have done an ON -> OFF transition: */ curr->hardirqs_enabled = 0; curr->hardirq_disable_ip = ip; curr->hardirq_disable_event = ++curr->irq_events; debug_atomic_inc(hardirqs_off_events); } else debug_atomic_inc(redundant_hardirqs_off); } /* * Softirqs will be enabled: */ void trace_softirqs_on(unsigned long ip) { struct task_struct *curr = current; if (unlikely(!debug_locks || current->lockdep_recursion)) return; /* * We fancy IRQs being disabled here, see softirq.c, avoids * funny state and nesting things. */ if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) return; if (curr->softirqs_enabled) { debug_atomic_inc(redundant_softirqs_on); return; } current->lockdep_recursion = 1; /* * We'll do an OFF -> ON transition: */ curr->softirqs_enabled = 1; curr->softirq_enable_ip = ip; curr->softirq_enable_event = ++curr->irq_events; debug_atomic_inc(softirqs_on_events); /* * We are going to turn softirqs on, so set the * usage bit for all held locks, if hardirqs are * enabled too: */ if (curr->hardirqs_enabled) mark_held_locks(curr, SOFTIRQ); current->lockdep_recursion = 0; } /* * Softirqs were disabled: */ void trace_softirqs_off(unsigned long ip) { struct task_struct *curr = current; if (unlikely(!debug_locks || current->lockdep_recursion)) return; /* * We fancy IRQs being disabled here, see softirq.c */ if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) return; if (curr->softirqs_enabled) { /* * We have done an ON -> OFF transition: */ curr->softirqs_enabled = 0; curr->softirq_disable_ip = ip; curr->softirq_disable_event = ++curr->irq_events; debug_atomic_inc(softirqs_off_events); /* * Whoops, we wanted softirqs off, so why aren't they? */ DEBUG_LOCKS_WARN_ON(!softirq_count()); } else debug_atomic_inc(redundant_softirqs_off); } static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock) { /* * If non-trylock use in a hardirq or softirq context, then * mark the lock as used in these contexts: */ if (!hlock->trylock) { if (hlock->read) { if (curr->hardirq_context) if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ_READ)) return 0; if (curr->softirq_context) if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ_READ)) return 0; } else { if (curr->hardirq_context) if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ)) return 0; if (curr->softirq_context) if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ)) return 0; } } if (!hlock->hardirqs_off) { if (hlock->read) { if (!mark_lock(curr, hlock, LOCK_ENABLED_HARDIRQ_READ)) return 0; if (curr->softirqs_enabled) if (!mark_lock(curr, hlock, LOCK_ENABLED_SOFTIRQ_READ)) return 0; } else { if (!mark_lock(curr, hlock, LOCK_ENABLED_HARDIRQ)) return 0; if (curr->softirqs_enabled) if (!mark_lock(curr, hlock, LOCK_ENABLED_SOFTIRQ)) return 0; } } return 1; } static inline unsigned int task_irq_context(struct task_struct *task) { return 2 * !!task->hardirq_context + !!task->softirq_context; } static int separate_irq_context(struct task_struct *curr, struct held_lock *hlock) { unsigned int depth = curr->lockdep_depth; /* * Keep track of points where we cross into an interrupt context: */ if (depth) { struct held_lock *prev_hlock; prev_hlock = curr->held_locks + depth-1; /* * If we cross into another context, reset the * hash key (this also prevents the checking and the * adding of the dependency to 'prev'): */ if (prev_hlock->irq_context != hlock->irq_context) return 1; } return 0; } #else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */ static inline int mark_lock_irq(struct task_struct *curr, struct held_lock *this, enum lock_usage_bit new_bit) { WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */ return 1; } static inline int mark_irqflags(struct task_struct *curr, struct held_lock *hlock) { return 1; } static inline unsigned int task_irq_context(struct task_struct *task) { return 0; } static inline int separate_irq_context(struct task_struct *curr, struct held_lock *hlock) { return 0; } #endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */ /* * Mark a lock with a usage bit, and validate the state transition: */ static int mark_lock(struct task_struct *curr, struct held_lock *this, enum lock_usage_bit new_bit) { unsigned int new_mask = 1 << new_bit, ret = 1; /* * If already set then do not dirty the cacheline, * nor do any checks: */ if (likely(hlock_class(this)->usage_mask & new_mask)) return 1; if (!graph_lock()) return 0; /* * Make sure we didn't race: */ if (unlikely(hlock_class(this)->usage_mask & new_mask)) { graph_unlock(); return 1; } hlock_class(this)->usage_mask |= new_mask; if (!save_trace(hlock_class(this)->usage_traces + new_bit)) return 0; switch (new_bit) { #define LOCKDEP_STATE(__STATE) \ case LOCK_USED_IN_##__STATE: \ case LOCK_USED_IN_##__STATE##_READ: \ case LOCK_ENABLED_##__STATE: \ case LOCK_ENABLED_##__STATE##_READ: #include "lockdep_states.h" #undef LOCKDEP_STATE ret = mark_lock_irq(curr, this, new_bit); if (!ret) return 0; break; case LOCK_USED: debug_atomic_dec(nr_unused_locks); break; default: if (!debug_locks_off_graph_unlock()) return 0; WARN_ON(1); return 0; } graph_unlock(); /* * We must printk outside of the graph_lock: */ if (ret == 2) { printk("\nmarked lock as {%s}:\n", usage_str[new_bit]); print_lock(this); print_irqtrace_events(curr); dump_stack(); } return ret; } /* * Initialize a lock instance's lock-class mapping info: */ void lockdep_init_map(struct lockdep_map *lock, const char *name, struct lock_class_key *key, int subclass) { int i; for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++) lock->class_cache[i] = NULL; #ifdef CONFIG_LOCK_STAT lock->cpu = raw_smp_processor_id(); #endif /* * Can't be having no nameless bastards around this place! */ if (DEBUG_LOCKS_WARN_ON(!name)) { lock->name = "NULL"; return; } lock->name = name; /* * No key, no joy, we need to hash something. */ if (DEBUG_LOCKS_WARN_ON(!key)) return; /* * Sanity check, the lock-class key must be persistent: */ if (!static_obj(key)) { printk("BUG: key %px not in .data!\n", key); /* * What it says above ^^^^^, I suggest you read it. */ DEBUG_LOCKS_WARN_ON(1); return; } lock->key = key; if (unlikely(!debug_locks)) return; if (subclass) { unsigned long flags; if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion)) return; raw_local_irq_save(flags); current->lockdep_recursion = 1; register_lock_class(lock, subclass, 1); current->lockdep_recursion = 0; raw_local_irq_restore(flags); } } EXPORT_SYMBOL_GPL(lockdep_init_map); struct lock_class_key __lockdep_no_validate__; EXPORT_SYMBOL_GPL(__lockdep_no_validate__); static int print_lock_nested_lock_not_held(struct task_struct *curr, struct held_lock *hlock, unsigned long ip) { if (!debug_locks_off()) return 0; if (debug_locks_silent) return 0; pr_warn("\n"); pr_warn("==================================\n"); pr_warn("WARNING: Nested lock was not taken\n"); print_kernel_ident(); pr_warn("----------------------------------\n"); pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr)); print_lock(hlock); pr_warn("\nbut this task is not holding:\n"); pr_warn("%s\n", hlock->nest_lock->name); pr_warn("\nstack backtrace:\n"); dump_stack(); pr_warn("\nother info that might help us debug this:\n"); lockdep_print_held_locks(curr); pr_warn("\nstack backtrace:\n"); dump_stack(); return 0; } static int __lock_is_held(const struct lockdep_map *lock, int read); /* * This gets called for every mutex_lock*()/spin_lock*() operation. * We maintain the dependency maps and validate the locking attempt: * * The callers must make sure that IRQs are disabled before calling it, * otherwise we could get an interrupt which would want to take locks, * which would end up in lockdep again. */ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, int trylock, int read, int check, int hardirqs_off, struct lockdep_map *nest_lock, unsigned long ip, int references, int pin_count) { struct task_struct *curr = current; struct lock_class *class = NULL; struct held_lock *hlock; unsigned int depth; int chain_head = 0; int class_idx; u64 chain_key; if (unlikely(!debug_locks)) return 0; if (!prove_locking || lock->key == &__lockdep_no_validate__) check = 0; if (subclass < NR_LOCKDEP_CACHING_CLASSES) class = lock->class_cache[subclass]; /* * Not cached? */ if (unlikely(!class)) { class = register_lock_class(lock, subclass, 0); if (!class) return 0; } debug_class_ops_inc(class); if (very_verbose(class)) { printk("\nacquire class [%px] %s", class->key, class->name); if (class->name_version > 1) printk(KERN_CONT "#%d", class->name_version); printk(KERN_CONT "\n"); dump_stack(); } /* * Add the lock to the list of currently held locks. * (we dont increase the depth just yet, up until the * dependency checks are done) */ depth = curr->lockdep_depth; /* * Ran out of static storage for our per-task lock stack again have we? */ if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH)) return 0; class_idx = class - lock_classes + 1; if (depth) { hlock = curr->held_locks + depth - 1; if (hlock->class_idx == class_idx && nest_lock) { if (hlock->references) { /* * Check: unsigned int references:12, overflow. */ if (DEBUG_LOCKS_WARN_ON(hlock->references == (1 << 12)-1)) return 0; hlock->references++; } else { hlock->references = 2; } return 1; } } hlock = curr->held_locks + depth; /* * Plain impossible, we just registered it and checked it weren't no * NULL like.. I bet this mushroom I ate was good! */ if (DEBUG_LOCKS_WARN_ON(!class)) return 0; hlock->class_idx = class_idx; hlock->acquire_ip = ip; hlock->instance = lock; hlock->nest_lock = nest_lock; hlock->irq_context = task_irq_context(curr); hlock->trylock = trylock; hlock->read = read; hlock->check = check; hlock->hardirqs_off = !!hardirqs_off; hlock->references = references; #ifdef CONFIG_LOCK_STAT hlock->waittime_stamp = 0; hlock->holdtime_stamp = lockstat_clock(); #endif hlock->pin_count = pin_count; if (check && !mark_irqflags(curr, hlock)) return 0; /* mark it as used: */ if (!mark_lock(curr, hlock, LOCK_USED)) return 0; /* * Calculate the chain hash: it's the combined hash of all the * lock keys along the dependency chain. We save the hash value * at every step so that we can get the current hash easily * after unlock. The chain hash is then used to cache dependency * results. * * The 'key ID' is what is the most compact key value to drive * the hash, not class->key. */ /* * Whoops, we did it again.. ran straight out of our static allocation. */ if (DEBUG_LOCKS_WARN_ON(class_idx > MAX_LOCKDEP_KEYS)) return 0; chain_key = curr->curr_chain_key; if (!depth) { /* * How can we have a chain hash when we ain't got no keys?! */ if (DEBUG_LOCKS_WARN_ON(chain_key != 0)) return 0; chain_head = 1; } hlock->prev_chain_key = chain_key; if (separate_irq_context(curr, hlock)) { chain_key = 0; chain_head = 1; } chain_key = iterate_chain_key(chain_key, class_idx); if (nest_lock && !__lock_is_held(nest_lock, -1)) return print_lock_nested_lock_not_held(curr, hlock, ip); if (!validate_chain(curr, lock, hlock, chain_head, chain_key)) return 0; curr->curr_chain_key = chain_key; curr->lockdep_depth++; check_chain_key(curr); #ifdef CONFIG_DEBUG_LOCKDEP if (unlikely(!debug_locks)) return 0; #endif if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) { debug_locks_off(); print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!"); printk(KERN_DEBUG "depth: %i max: %lu!\n", curr->lockdep_depth, MAX_LOCK_DEPTH); lockdep_print_held_locks(current); debug_show_all_locks(); dump_stack(); return 0; } if (unlikely(curr->lockdep_depth > max_lockdep_depth)) max_lockdep_depth = curr->lockdep_depth; return 1; } static int print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock, unsigned long ip) { if (!debug_locks_off()) return 0; if (debug_locks_silent) return 0; pr_warn("\n"); pr_warn("=====================================\n"); pr_warn("WARNING: bad unlock balance detected!\n"); print_kernel_ident(); pr_warn("-------------------------------------\n"); pr_warn("%s/%d is trying to release lock (", curr->comm, task_pid_nr(curr)); print_lockdep_cache(lock); pr_cont(") at:\n"); print_ip_sym(ip); pr_warn("but there are no more locks to release!\n"); pr_warn("\nother info that might help us debug this:\n"); lockdep_print_held_locks(curr); pr_warn("\nstack backtrace:\n"); dump_stack(); return 0; } static int match_held_lock(const struct held_lock *hlock, const struct lockdep_map *lock) { if (hlock->instance == lock) return 1; if (hlock->references) { const struct lock_class *class = lock->class_cache[0]; if (!class) class = look_up_lock_class(lock, 0); /* * If look_up_lock_class() failed to find a class, we're trying * to test if we hold a lock that has never yet been acquired. * Clearly if the lock hasn't been acquired _ever_, we're not * holding it either, so report failure. */ if (!class) return 0; /* * References, but not a lock we're actually ref-counting? * State got messed up, follow the sites that change ->references * and try to make sense of it. */ if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock)) return 0; if (hlock->class_idx == class - lock_classes + 1) return 1; } return 0; } /* @depth must not be zero */ static struct held_lock *find_held_lock(struct task_struct *curr, struct lockdep_map *lock, unsigned int depth, int *idx) { struct held_lock *ret, *hlock, *prev_hlock; int i; i = depth - 1; hlock = curr->held_locks + i; ret = hlock; if (match_held_lock(hlock, lock)) goto out; ret = NULL; for (i--, prev_hlock = hlock--; i >= 0; i--, prev_hlock = hlock--) { /* * We must not cross into another context: */ if (prev_hlock->irq_context != hlock->irq_context) { ret = NULL; break; } if (match_held_lock(hlock, lock)) { ret = hlock; break; } } out: *idx = i; return ret; } static int reacquire_held_locks(struct task_struct *curr, unsigned int depth, int idx) { struct held_lock *hlock; if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) return 0; for (hlock = curr->held_locks + idx; idx < depth; idx++, hlock++) { if (!__lock_acquire(hlock->instance, hlock_class(hlock)->subclass, hlock->trylock, hlock->read, hlock->check, hlock->hardirqs_off, hlock->nest_lock, hlock->acquire_ip, hlock->references, hlock->pin_count)) return 1; } return 0; } static int __lock_set_class(struct lockdep_map *lock, const char *name, struct lock_class_key *key, unsigned int subclass, unsigned long ip) { struct task_struct *curr = current; struct held_lock *hlock; struct lock_class *class; unsigned int depth; int i; depth = curr->lockdep_depth; /* * This function is about (re)setting the class of a held lock, * yet we're not actually holding any locks. Naughty user! */ if (DEBUG_LOCKS_WARN_ON(!depth)) return 0; hlock = find_held_lock(curr, lock, depth, &i); if (!hlock) return print_unlock_imbalance_bug(curr, lock, ip); lockdep_init_map(lock, name, key, 0); class = register_lock_class(lock, subclass, 0); hlock->class_idx = class - lock_classes + 1; curr->lockdep_depth = i; curr->curr_chain_key = hlock->prev_chain_key; if (reacquire_held_locks(curr, depth, i)) return 0; /* * I took it apart and put it back together again, except now I have * these 'spare' parts.. where shall I put them. */ if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth)) return 0; return 1; } static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip) { struct task_struct *curr = current; struct held_lock *hlock; unsigned int depth; int i; depth = curr->lockdep_depth; /* * This function is about (re)setting the class of a held lock, * yet we're not actually holding any locks. Naughty user! */ if (DEBUG_LOCKS_WARN_ON(!depth)) return 0; hlock = find_held_lock(curr, lock, depth, &i); if (!hlock) return print_unlock_imbalance_bug(curr, lock, ip); curr->lockdep_depth = i; curr->curr_chain_key = hlock->prev_chain_key; WARN(hlock->read, "downgrading a read lock"); hlock->read = 1; hlock->acquire_ip = ip; if (reacquire_held_locks(curr, depth, i)) return 0; /* * I took it apart and put it back together again, except now I have * these 'spare' parts.. where shall I put them. */ if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth)) return 0; return 1; } /* * Remove the lock to the list of currently held locks - this gets * called on mutex_unlock()/spin_unlock*() (or on a failed * mutex_lock_interruptible()). * * @nested is an hysterical artifact, needs a tree wide cleanup. */ static int __lock_release(struct lockdep_map *lock, int nested, unsigned long ip) { struct task_struct *curr = current; struct held_lock *hlock; unsigned int depth; int i; if (unlikely(!debug_locks)) return 0; depth = curr->lockdep_depth; /* * So we're all set to release this lock.. wait what lock? We don't * own any locks, you've been drinking again? */ if (DEBUG_LOCKS_WARN_ON(depth <= 0)) return print_unlock_imbalance_bug(curr, lock, ip); /* * Check whether the lock exists in the current stack * of held locks: */ hlock = find_held_lock(curr, lock, depth, &i); if (!hlock) return print_unlock_imbalance_bug(curr, lock, ip); if (hlock->instance == lock) lock_release_holdtime(hlock); WARN(hlock->pin_count, "releasing a pinned lock\n"); if (hlock->references) { hlock->references--; if (hlock->references) { /* * We had, and after removing one, still have * references, the current lock stack is still * valid. We're done! */ return 1; } } /* * We have the right lock to unlock, 'hlock' points to it. * Now we remove it from the stack, and add back the other * entries (if any), recalculating the hash along the way: */ curr->lockdep_depth = i; curr->curr_chain_key = hlock->prev_chain_key; /* * The most likely case is when the unlock is on the innermost * lock. In this case, we are done! */ if (i == depth-1) return 1; if (reacquire_held_locks(curr, depth, i + 1)) return 0; /* * We had N bottles of beer on the wall, we drank one, but now * there's not N-1 bottles of beer left on the wall... */ DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth-1); /* * Since reacquire_held_locks() would have called check_chain_key() * indirectly via __lock_acquire(), we don't need to do it again * on return. */ return 0; } static int __lock_is_held(const struct lockdep_map *lock, int read) { struct task_struct *curr = current; int i; for (i = 0; i < curr->lockdep_depth; i++) { struct held_lock *hlock = curr->held_locks + i; if (match_held_lock(hlock, lock)) { if (read == -1 || hlock->read == read) return 1; return 0; } } return 0; } static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock) { struct pin_cookie cookie = NIL_COOKIE; struct task_struct *curr = current; int i; if (unlikely(!debug_locks)) return cookie; for (i = 0; i < curr->lockdep_depth; i++) { struct held_lock *hlock = curr->held_locks + i; if (match_held_lock(hlock, lock)) { /* * Grab 16bits of randomness; this is sufficient to not * be guessable and still allows some pin nesting in * our u32 pin_count. */ cookie.val = 1 + (prandom_u32() >> 16); hlock->pin_count += cookie.val; return cookie; } } WARN(1, "pinning an unheld lock\n"); return cookie; } static void __lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie) { struct task_struct *curr = current; int i; if (unlikely(!debug_locks)) return; for (i = 0; i < curr->lockdep_depth; i++) { struct held_lock *hlock = curr->held_locks + i; if (match_held_lock(hlock, lock)) { hlock->pin_count += cookie.val; return; } } WARN(1, "pinning an unheld lock\n"); } static void __lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie) { struct task_struct *curr = current; int i; if (unlikely(!debug_locks)) return; for (i = 0; i < curr->lockdep_depth; i++) { struct held_lock *hlock = curr->held_locks + i; if (match_held_lock(hlock, lock)) { if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n")) return; hlock->pin_count -= cookie.val; if (WARN((int)hlock->pin_count < 0, "pin count corrupted\n")) hlock->pin_count = 0; return; } } WARN(1, "unpinning an unheld lock\n"); } /* * Check whether we follow the irq-flags state precisely: */ static void check_flags(unsigned long flags) { #if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \ defined(CONFIG_TRACE_IRQFLAGS) if (!debug_locks) return; if (irqs_disabled_flags(flags)) { if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) { printk("possible reason: unannotated irqs-off.\n"); } } else { if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) { printk("possible reason: unannotated irqs-on.\n"); } } /* * We dont accurately track softirq state in e.g. * hardirq contexts (such as on 4KSTACKS), so only * check if not in hardirq contexts: */ if (!hardirq_count()) { if (softirq_count()) { /* like the above, but with softirqs */ DEBUG_LOCKS_WARN_ON(current->softirqs_enabled); } else { /* lick the above, does it taste good? */ DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled); } } if (!debug_locks) print_irqtrace_events(current); #endif } void lock_set_class(struct lockdep_map *lock, const char *name, struct lock_class_key *key, unsigned int subclass, unsigned long ip) { unsigned long flags; if (unlikely(current->lockdep_recursion)) return; raw_local_irq_save(flags); current->lockdep_recursion = 1; check_flags(flags); if (__lock_set_class(lock, name, key, subclass, ip)) check_chain_key(current); current->lockdep_recursion = 0; raw_local_irq_restore(flags); } EXPORT_SYMBOL_GPL(lock_set_class); void lock_downgrade(struct lockdep_map *lock, unsigned long ip) { unsigned long flags; if (unlikely(current->lockdep_recursion)) return; raw_local_irq_save(flags); current->lockdep_recursion = 1; check_flags(flags); if (__lock_downgrade(lock, ip)) check_chain_key(current); current->lockdep_recursion = 0; raw_local_irq_restore(flags); } EXPORT_SYMBOL_GPL(lock_downgrade); /* * We are not always called with irqs disabled - do that here, * and also avoid lockdep recursion: */ void lock_acquire(struct lockdep_map *lock, unsigned int subclass, int trylock, int read, int check, struct lockdep_map *nest_lock, unsigned long ip) { unsigned long flags; if (unlikely(current->lockdep_recursion)) return; raw_local_irq_save(flags); check_flags(flags); current->lockdep_recursion = 1; trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip); __lock_acquire(lock, subclass, trylock, read, check, irqs_disabled_flags(flags), nest_lock, ip, 0, 0); current->lockdep_recursion = 0; raw_local_irq_restore(flags); } EXPORT_SYMBOL_GPL(lock_acquire); void lock_release(struct lockdep_map *lock, int nested, unsigned long ip) { unsigned long flags; if (unlikely(current->lockdep_recursion)) return; raw_local_irq_save(flags); check_flags(flags); current->lockdep_recursion = 1; trace_lock_release(lock, ip); if (__lock_release(lock, nested, ip)) check_chain_key(current); current->lockdep_recursion = 0; raw_local_irq_restore(flags); } EXPORT_SYMBOL_GPL(lock_release); int lock_is_held_type(const struct lockdep_map *lock, int read) { unsigned long flags; int ret = 0; if (unlikely(current->lockdep_recursion)) return 1; /* avoid false negative lockdep_assert_held() */ raw_local_irq_save(flags); check_flags(flags); current->lockdep_recursion = 1; ret = __lock_is_held(lock, read); current->lockdep_recursion = 0; raw_local_irq_restore(flags); return ret; } EXPORT_SYMBOL_GPL(lock_is_held_type); struct pin_cookie lock_pin_lock(struct lockdep_map *lock) { struct pin_cookie cookie = NIL_COOKIE; unsigned long flags; if (unlikely(current->lockdep_recursion)) return cookie; raw_local_irq_save(flags); check_flags(flags); current->lockdep_recursion = 1; cookie = __lock_pin_lock(lock); current->lockdep_recursion = 0; raw_local_irq_restore(flags); return cookie; } EXPORT_SYMBOL_GPL(lock_pin_lock); void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie) { unsigned long flags; if (unlikely(current->lockdep_recursion)) return; raw_local_irq_save(flags); check_flags(flags); current->lockdep_recursion = 1; __lock_repin_lock(lock, cookie); current->lockdep_recursion = 0; raw_local_irq_restore(flags); } EXPORT_SYMBOL_GPL(lock_repin_lock); void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie) { unsigned long flags; if (unlikely(current->lockdep_recursion)) return; raw_local_irq_save(flags); check_flags(flags); current->lockdep_recursion = 1; __lock_unpin_lock(lock, cookie); current->lockdep_recursion = 0; raw_local_irq_restore(flags); } EXPORT_SYMBOL_GPL(lock_unpin_lock); #ifdef CONFIG_LOCK_STAT static int print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock, unsigned long ip) { if (!debug_locks_off()) return 0; if (debug_locks_silent) return 0; pr_warn("\n"); pr_warn("=================================\n"); pr_warn("WARNING: bad contention detected!\n"); print_kernel_ident(); pr_warn("---------------------------------\n"); pr_warn("%s/%d is trying to contend lock (", curr->comm, task_pid_nr(curr)); print_lockdep_cache(lock); pr_cont(") at:\n"); print_ip_sym(ip); pr_warn("but there are no locks held!\n"); pr_warn("\nother info that might help us debug this:\n"); lockdep_print_held_locks(curr); pr_warn("\nstack backtrace:\n"); dump_stack(); return 0; } static void __lock_contended(struct lockdep_map *lock, unsigned long ip) { struct task_struct *curr = current; struct held_lock *hlock; struct lock_class_stats *stats; unsigned int depth; int i, contention_point, contending_point; depth = curr->lockdep_depth; /* * Whee, we contended on this lock, except it seems we're not * actually trying to acquire anything much at all.. */ if (DEBUG_LOCKS_WARN_ON(!depth)) return; hlock = find_held_lock(curr, lock, depth, &i); if (!hlock) { print_lock_contention_bug(curr, lock, ip); return; } if (hlock->instance != lock) return; hlock->waittime_stamp = lockstat_clock(); contention_point = lock_point(hlock_class(hlock)->contention_point, ip); contending_point = lock_point(hlock_class(hlock)->contending_point, lock->ip); stats = get_lock_stats(hlock_class(hlock)); if (contention_point < LOCKSTAT_POINTS) stats->contention_point[contention_point]++; if (contending_point < LOCKSTAT_POINTS) stats->contending_point[contending_point]++; if (lock->cpu != smp_processor_id()) stats->bounces[bounce_contended + !!hlock->read]++; } static void __lock_acquired(struct lockdep_map *lock, unsigned long ip) { struct task_struct *curr = current; struct held_lock *hlock; struct lock_class_stats *stats; unsigned int depth; u64 now, waittime = 0; int i, cpu; depth = curr->lockdep_depth; /* * Yay, we acquired ownership of this lock we didn't try to * acquire, how the heck did that happen? */ if (DEBUG_LOCKS_WARN_ON(!depth)) return; hlock = find_held_lock(curr, lock, depth, &i); if (!hlock) { print_lock_contention_bug(curr, lock, _RET_IP_); return; } if (hlock->instance != lock) return; cpu = smp_processor_id(); if (hlock->waittime_stamp) { now = lockstat_clock(); waittime = now - hlock->waittime_stamp; hlock->holdtime_stamp = now; } trace_lock_acquired(lock, ip); stats = get_lock_stats(hlock_class(hlock)); if (waittime) { if (hlock->read) lock_time_inc(&stats->read_waittime, waittime); else lock_time_inc(&stats->write_waittime, waittime); } if (lock->cpu != cpu) stats->bounces[bounce_acquired + !!hlock->read]++; lock->cpu = cpu; lock->ip = ip; } void lock_contended(struct lockdep_map *lock, unsigned long ip) { unsigned long flags; if (unlikely(!lock_stat || !debug_locks)) return; if (unlikely(current->lockdep_recursion)) return; raw_local_irq_save(flags); check_flags(flags); current->lockdep_recursion = 1; trace_lock_contended(lock, ip); __lock_contended(lock, ip); current->lockdep_recursion = 0; raw_local_irq_restore(flags); } EXPORT_SYMBOL_GPL(lock_contended); void lock_acquired(struct lockdep_map *lock, unsigned long ip) { unsigned long flags; if (unlikely(!lock_stat || !debug_locks)) return; if (unlikely(current->lockdep_recursion)) return; raw_local_irq_save(flags); check_flags(flags); current->lockdep_recursion = 1; __lock_acquired(lock, ip); current->lockdep_recursion = 0; raw_local_irq_restore(flags); } EXPORT_SYMBOL_GPL(lock_acquired); #endif /* * Used by the testsuite, sanitize the validator state * after a simulated failure: */ void lockdep_reset(void) { unsigned long flags; int i; raw_local_irq_save(flags); current->curr_chain_key = 0; current->lockdep_depth = 0; current->lockdep_recursion = 0; memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock)); nr_hardirq_chains = 0; nr_softirq_chains = 0; nr_process_chains = 0; debug_locks = 1; for (i = 0; i < CHAINHASH_SIZE; i++) INIT_HLIST_HEAD(chainhash_table + i); raw_local_irq_restore(flags); } /* * Remove all references to a lock class. The caller must hold the graph lock. */ static void zap_class(struct lock_class *class) { int i; /* * Remove all dependencies this lock is * involved in: */ for (i = 0; i < nr_list_entries; i++) { if (list_entries[i].class == class) list_del_rcu(&list_entries[i].entry); } /* * Unhash the class and remove it from the all_lock_classes list: */ hlist_del_rcu(&class->hash_entry); list_del(&class->lock_entry); RCU_INIT_POINTER(class->key, NULL); RCU_INIT_POINTER(class->name, NULL); } static inline int within(const void *addr, void *start, unsigned long size) { return addr >= start && addr < start + size; } /* * Used in module.c to remove lock classes from memory that is going to be * freed; and possibly re-used by other modules. * * We will have had one sync_sched() before getting here, so we're guaranteed * nobody will look up these exact classes -- they're properly dead but still * allocated. */ void lockdep_free_key_range(void *start, unsigned long size) { struct lock_class *class; struct hlist_head *head; unsigned long flags; int i; int locked; raw_local_irq_save(flags); locked = graph_lock(); /* * Unhash all classes that were created by this module: */ for (i = 0; i < CLASSHASH_SIZE; i++) { head = classhash_table + i; hlist_for_each_entry_rcu(class, head, hash_entry) { if (within(class->key, start, size)) zap_class(class); else if (within(class->name, start, size)) zap_class(class); } } if (locked) graph_unlock(); raw_local_irq_restore(flags); /* * Wait for any possible iterators from look_up_lock_class() to pass * before continuing to free the memory they refer to. * * sync_sched() is sufficient because the read-side is IRQ disable. */ synchronize_rcu(); /* * XXX at this point we could return the resources to the pool; * instead we leak them. We would need to change to bitmap allocators * instead of the linear allocators we have now. */ } /* * Check whether any element of the @lock->class_cache[] array refers to a * registered lock class. The caller must hold either the graph lock or the * RCU read lock. */ static bool lock_class_cache_is_registered(struct lockdep_map *lock) { struct lock_class *class; struct hlist_head *head; int i, j; for (i = 0; i < CLASSHASH_SIZE; i++) { head = classhash_table + i; hlist_for_each_entry_rcu(class, head, hash_entry) { for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++) if (lock->class_cache[j] == class) return true; } } return false; } void lockdep_reset_lock(struct lockdep_map *lock) { struct lock_class *class; unsigned long flags; int j, locked; raw_local_irq_save(flags); locked = graph_lock(); /* * Remove all classes this lock might have: */ for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) { /* * If the class exists we look it up and zap it: */ class = look_up_lock_class(lock, j); if (class) zap_class(class); } /* * Debug check: in the end all mapped classes should * be gone. */ if (unlikely(lock_class_cache_is_registered(lock))) { if (debug_locks_off_graph_unlock()) { /* * We all just reset everything, how did it match? */ WARN_ON(1); } goto out_restore; } if (locked) graph_unlock(); out_restore: raw_local_irq_restore(flags); } void __init lockdep_init(void) { printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n"); printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES); printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH); printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS); printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE); printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES); printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS); printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE); printk(" memory used by lock dependency info: %lu kB\n", (sizeof(struct lock_class) * MAX_LOCKDEP_KEYS + sizeof(struct list_head) * CLASSHASH_SIZE + sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES + sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS + sizeof(struct list_head) * CHAINHASH_SIZE #ifdef CONFIG_PROVE_LOCKING + sizeof(struct circular_queue) #endif ) / 1024 ); printk(" per task-struct memory footprint: %lu bytes\n", sizeof(struct held_lock) * MAX_LOCK_DEPTH); } static void print_freed_lock_bug(struct task_struct *curr, const void *mem_from, const void *mem_to, struct held_lock *hlock) { if (!debug_locks_off()) return; if (debug_locks_silent) return; pr_warn("\n"); pr_warn("=========================\n"); pr_warn("WARNING: held lock freed!\n"); print_kernel_ident(); pr_warn("-------------------------\n"); pr_warn("%s/%d is freeing memory %px-%px, with a lock still held there!\n", curr->comm, task_pid_nr(curr), mem_from, mem_to-1); print_lock(hlock); lockdep_print_held_locks(curr); pr_warn("\nstack backtrace:\n"); dump_stack(); } static inline int not_in_range(const void* mem_from, unsigned long mem_len, const void* lock_from, unsigned long lock_len) { return lock_from + lock_len <= mem_from || mem_from + mem_len <= lock_from; } /* * Called when kernel memory is freed (or unmapped), or if a lock * is destroyed or reinitialized - this code checks whether there is * any held lock in the memory range of <from> to <to>: */ void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len) { struct task_struct *curr = current; struct held_lock *hlock; unsigned long flags; int i; if (unlikely(!debug_locks)) return; raw_local_irq_save(flags); for (i = 0; i < curr->lockdep_depth; i++) { hlock = curr->held_locks + i; if (not_in_range(mem_from, mem_len, hlock->instance, sizeof(*hlock->instance))) continue; print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock); break; } raw_local_irq_restore(flags); } EXPORT_SYMBOL_GPL(debug_check_no_locks_freed); static void print_held_locks_bug(void) { if (!debug_locks_off()) return; if (debug_locks_silent) return; pr_warn("\n"); pr_warn("====================================\n"); pr_warn("WARNING: %s/%d still has locks held!\n", current->comm, task_pid_nr(current)); print_kernel_ident(); pr_warn("------------------------------------\n"); lockdep_print_held_locks(current); pr_warn("\nstack backtrace:\n"); dump_stack(); } void debug_check_no_locks_held(void) { if (unlikely(current->lockdep_depth > 0)) print_held_locks_bug(); } EXPORT_SYMBOL_GPL(debug_check_no_locks_held); #ifdef __KERNEL__ void debug_show_all_locks(void) { struct task_struct *g, *p; if (unlikely(!debug_locks)) { pr_warn("INFO: lockdep is turned off.\n"); return; } pr_warn("\nShowing all locks held in the system:\n"); rcu_read_lock(); for_each_process_thread(g, p) { if (!p->lockdep_depth) continue; lockdep_print_held_locks(p); touch_nmi_watchdog(); touch_all_softlockup_watchdogs(); } rcu_read_unlock(); pr_warn("\n"); pr_warn("=============================================\n\n"); } EXPORT_SYMBOL_GPL(debug_show_all_locks); #endif /* * Careful: only use this function if you are sure that * the task cannot run in parallel! */ void debug_show_held_locks(struct task_struct *task) { if (unlikely(!debug_locks)) { printk("INFO: lockdep is turned off.\n"); return; } lockdep_print_held_locks(task); } EXPORT_SYMBOL_GPL(debug_show_held_locks); asmlinkage __visible void lockdep_sys_exit(void) { struct task_struct *curr = current; if (unlikely(curr->lockdep_depth)) { if (!debug_locks_off()) return; pr_warn("\n"); pr_warn("================================================\n"); pr_warn("WARNING: lock held when returning to user space!\n"); print_kernel_ident(); pr_warn("------------------------------------------------\n"); pr_warn("%s/%d is leaving the kernel with locks still held!\n", curr->comm, curr->pid); lockdep_print_held_locks(curr); } /* * The lock history for each syscall should be independent. So wipe the * slate clean on return to userspace. */ lockdep_invariant_state(false); } void lockdep_rcu_suspicious(const char *file, const int line, const char *s) { struct task_struct *curr = current; /* Note: the following can be executed concurrently, so be careful. */ pr_warn("\n"); pr_warn("=============================\n"); pr_warn("WARNING: suspicious RCU usage\n"); print_kernel_ident(); pr_warn("-----------------------------\n"); pr_warn("%s:%d %s!\n", file, line, s); pr_warn("\nother info that might help us debug this:\n\n"); pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n", !rcu_lockdep_current_cpu_online() ? "RCU used illegally from offline CPU!\n" : !rcu_is_watching() ? "RCU used illegally from idle CPU!\n" : "", rcu_scheduler_active, debug_locks); /* * If a CPU is in the RCU-free window in idle (ie: in the section * between rcu_idle_enter() and rcu_idle_exit(), then RCU * considers that CPU to be in an "extended quiescent state", * which means that RCU will be completely ignoring that CPU. * Therefore, rcu_read_lock() and friends have absolutely no * effect on a CPU running in that state. In other words, even if * such an RCU-idle CPU has called rcu_read_lock(), RCU might well * delete data structures out from under it. RCU really has no * choice here: we need to keep an RCU-free window in idle where * the CPU may possibly enter into low power mode. This way we can * notice an extended quiescent state to other CPUs that started a grace * period. Otherwise we would delay any grace period as long as we run * in the idle task. * * So complain bitterly if someone does call rcu_read_lock(), * rcu_read_lock_bh() and so on from extended quiescent states. */ if (!rcu_is_watching()) pr_warn("RCU used illegally from extended quiescent state!\n"); lockdep_print_held_locks(curr); pr_warn("\nstack backtrace:\n"); dump_stack(); } EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);
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