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Release 4.15 include/linux/spinlock.h

Directory: include/linux
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __LINUX_SPINLOCK_H

#define __LINUX_SPINLOCK_H

/*
 * include/linux/spinlock.h - generic spinlock/rwlock declarations
 *
 * here's the role of the various spinlock/rwlock related include files:
 *
 * on SMP builds:
 *
 *  asm/spinlock_types.h: contains the arch_spinlock_t/arch_rwlock_t and the
 *                        initializers
 *
 *  linux/spinlock_types.h:
 *                        defines the generic type and initializers
 *
 *  asm/spinlock.h:       contains the arch_spin_*()/etc. lowlevel
 *                        implementations, mostly inline assembly code
 *
 *   (also included on UP-debug builds:)
 *
 *  linux/spinlock_api_smp.h:
 *                        contains the prototypes for the _spin_*() APIs.
 *
 *  linux/spinlock.h:     builds the final spin_*() APIs.
 *
 * on UP builds:
 *
 *  linux/spinlock_type_up.h:
 *                        contains the generic, simplified UP spinlock type.
 *                        (which is an empty structure on non-debug builds)
 *
 *  linux/spinlock_types.h:
 *                        defines the generic type and initializers
 *
 *  linux/spinlock_up.h:
 *                        contains the arch_spin_*()/etc. version of UP
 *                        builds. (which are NOPs on non-debug, non-preempt
 *                        builds)
 *
 *   (included on UP-non-debug builds:)
 *
 *  linux/spinlock_api_up.h:
 *                        builds the _spin_*() APIs.
 *
 *  linux/spinlock.h:     builds the final spin_*() APIs.
 */

#include <linux/typecheck.h>
#include <linux/preempt.h>
#include <linux/linkage.h>
#include <linux/compiler.h>
#include <linux/irqflags.h>
#include <linux/thread_info.h>
#include <linux/kernel.h>
#include <linux/stringify.h>
#include <linux/bottom_half.h>
#include <asm/barrier.h>


/*
 * Must define these before including other files, inline functions need them
 */

#define LOCK_SECTION_NAME ".text..lock."KBUILD_BASENAME


#define LOCK_SECTION_START(extra)               \
        ".subsection 1\n\t"                     \
        extra                                   \
        ".ifndef " LOCK_SECTION_NAME "\n\t"     \
        LOCK_SECTION_NAME ":\n\t"               \
        ".endif\n"


#define LOCK_SECTION_END                        \
        ".previous\n\t"


#define __lockfunc __attribute__((section(".spinlock.text")))

/*
 * Pull the arch_spinlock_t and arch_rwlock_t definitions:
 */
#include <linux/spinlock_types.h>

/*
 * Pull the arch_spin*() functions/declarations (UP-nondebug doesn't need them):
 */
#ifdef CONFIG_SMP
# include <asm/spinlock.h>
#else
# include <linux/spinlock_up.h>
#endif

#ifdef CONFIG_DEBUG_SPINLOCK
  extern void __raw_spin_lock_init(raw_spinlock_t *lock, const char *name,
				   struct lock_class_key *key);

# define raw_spin_lock_init(lock)				\
do {                                                            \
        static struct lock_class_key __key;                     \
                                                                \
        __raw_spin_lock_init((lock), #lock, &__key);            \
} while (0)

#else

# define raw_spin_lock_init(lock)				\
	do { *(lock) = __RAW_SPIN_LOCK_UNLOCKED(lock); } while (0)
#endif


#define raw_spin_is_locked(lock)	arch_spin_is_locked(&(lock)->raw_lock)

#ifdef arch_spin_is_contended

#define raw_spin_is_contended(lock)	arch_spin_is_contended(&(lock)->raw_lock)
#else

#define raw_spin_is_contended(lock)	(((void)(lock), 0))
#endif /*arch_spin_is_contended*/

/*
 * This barrier must provide two things:
 *
 *   - it must guarantee a STORE before the spin_lock() is ordered against a
 *     LOAD after it, see the comments at its two usage sites.
 *
 *   - it must ensure the critical section is RCsc.
 *
 * The latter is important for cases where we observe values written by other
 * CPUs in spin-loops, without barriers, while being subject to scheduling.
 *
 * CPU0                 CPU1                    CPU2
 *
 *                      for (;;) {
 *                        if (READ_ONCE(X))
 *                          break;
 *                      }
 * X=1
 *                      <sched-out>
 *                                              <sched-in>
 *                                              r = X;
 *
 * without transitivity it could be that CPU1 observes X!=0 breaks the loop,
 * we get migrated and CPU2 sees X==0.
 *
 * Since most load-store architectures implement ACQUIRE with an smp_mb() after
 * the LL/SC loop, they need no further barriers. Similarly all our TSO
 * architectures imply an smp_mb() for each atomic instruction and equally don't
 * need more.
 *
 * Architectures that can implement ACQUIRE better need to take care.
 */
#ifndef smp_mb__after_spinlock

#define smp_mb__after_spinlock()	do { } while (0)
#endif

#ifdef CONFIG_DEBUG_SPINLOCK
 
extern void do_raw_spin_lock(raw_spinlock_t *lock) __acquires(lock);

#define do_raw_spin_lock_flags(lock, flags) do_raw_spin_lock(lock)
 extern int do_raw_spin_trylock(raw_spinlock_t *lock);
 
extern void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock);
#else

static inline void do_raw_spin_lock(raw_spinlock_t *lock) __acquires(lock) { __acquire(lock); arch_spin_lock(&lock->raw_lock); }

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Thomas Gleixner1657.14%250.00%
Luca Barbieri932.14%125.00%
Linus Torvalds310.71%125.00%
Total28100.00%4100.00%

#ifndef arch_spin_lock_flags #define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock) #endif
static inline void do_raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long *flags) __acquires(lock) { __acquire(lock); arch_spin_lock_flags(&lock->raw_lock, *flags); }

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Thomas Gleixner2261.11%240.00%
Luca Barbieri925.00%120.00%
Linus Torvalds38.33%120.00%
Ingo Molnar25.56%120.00%
Total36100.00%5100.00%


static inline int do_raw_spin_trylock(raw_spinlock_t *lock) { return arch_spin_trylock(&(lock)->raw_lock); }

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Thomas Gleixner1986.36%266.67%
Linus Torvalds313.64%133.33%
Total22100.00%3100.00%


static inline void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock) { arch_spin_unlock(&lock->raw_lock); __release(lock); }

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Thomas Gleixner1657.14%250.00%
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Linus Torvalds310.71%125.00%
Total28100.00%4100.00%

#endif /* * Define the various spin_lock methods. Note we define these * regardless of whether CONFIG_SMP or CONFIG_PREEMPT are set. The * various methods are defined as nops in the case they are not * required. */ #define raw_spin_trylock(lock) __cond_lock(lock, _raw_spin_trylock(lock)) #define raw_spin_lock(lock) _raw_spin_lock(lock) #ifdef CONFIG_DEBUG_LOCK_ALLOC # define raw_spin_lock_nested(lock, subclass) \ _raw_spin_lock_nested(lock, subclass) # define raw_spin_lock_nest_lock(lock, nest_lock) \ do { \ typecheck(struct lockdep_map *, &(nest_lock)->dep_map);\ _raw_spin_lock_nest_lock(lock, &(nest_lock)->dep_map); \ } while (0) #else /* * Always evaluate the 'subclass' argument to avoid that the compiler * warns about set-but-not-used variables when building with * CONFIG_DEBUG_LOCK_ALLOC=n and with W=1. */ # define raw_spin_lock_nested(lock, subclass) \ _raw_spin_lock(((void)(subclass), (lock))) # define raw_spin_lock_nest_lock(lock, nest_lock) _raw_spin_lock(lock) #endif #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) #define raw_spin_lock_irqsave(lock, flags) \ do { \ typecheck(unsigned long, flags); \ flags = _raw_spin_lock_irqsave(lock); \ } while (0) #ifdef CONFIG_DEBUG_LOCK_ALLOC #define raw_spin_lock_irqsave_nested(lock, flags, subclass) \ do { \ typecheck(unsigned long, flags); \ flags = _raw_spin_lock_irqsave_nested(lock, subclass); \ } while (0) #else #define raw_spin_lock_irqsave_nested(lock, flags, subclass) \ do { \ typecheck(unsigned long, flags); \ flags = _raw_spin_lock_irqsave(lock); \ } while (0) #endif #else #define raw_spin_lock_irqsave(lock, flags) \ do { \ typecheck(unsigned long, flags); \ _raw_spin_lock_irqsave(lock, flags); \ } while (0) #define raw_spin_lock_irqsave_nested(lock, flags, subclass) \ raw_spin_lock_irqsave(lock, flags) #endif #define raw_spin_lock_irq(lock) _raw_spin_lock_irq(lock) #define raw_spin_lock_bh(lock) _raw_spin_lock_bh(lock) #define raw_spin_unlock(lock) _raw_spin_unlock(lock) #define raw_spin_unlock_irq(lock) _raw_spin_unlock_irq(lock) #define raw_spin_unlock_irqrestore(lock, flags) \ do { \ typecheck(unsigned long, flags); \ _raw_spin_unlock_irqrestore(lock, flags); \ } while (0) #define raw_spin_unlock_bh(lock) _raw_spin_unlock_bh(lock) #define raw_spin_trylock_bh(lock) \ __cond_lock(lock, _raw_spin_trylock_bh(lock)) #define raw_spin_trylock_irq(lock) \ ({ \ local_irq_disable(); \ raw_spin_trylock(lock) ? \ 1 : ({ local_irq_enable(); 0; }); \ }) #define raw_spin_trylock_irqsave(lock, flags) \ ({ \ local_irq_save(flags); \ raw_spin_trylock(lock) ? \ 1 : ({ local_irq_restore(flags); 0; }); \ }) /* Include rwlock functions */ #include <linux/rwlock.h> /* * Pull the _spin_*()/_read_*()/_write_*() functions/declarations: */ #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) # include <linux/spinlock_api_smp.h> #else # include <linux/spinlock_api_up.h> #endif /* * Map the spin_lock functions to the raw variants for PREEMPT_RT=n */
static __always_inline raw_spinlock_t *spinlock_check(spinlock_t *lock) { return &lock->rlock; }

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#define spin_lock_init(_lock) \ do { \ spinlock_check(_lock); \ raw_spin_lock_init(&(_lock)->rlock); \ } while (0)
static __always_inline void spin_lock(spinlock_t *lock) { raw_spin_lock(&lock->rlock); }

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Thomas Gleixner1894.74%150.00%
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Total19100.00%2100.00%


static __always_inline void spin_lock_bh(spinlock_t *lock) { raw_spin_lock_bh(&lock->rlock); }

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Thomas Gleixner1894.74%150.00%
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Total19100.00%2100.00%


static __always_inline int spin_trylock(spinlock_t *lock) { return raw_spin_trylock(&lock->rlock); }

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Thomas Gleixner1995.00%150.00%
Denys Vlasenko15.00%150.00%
Total20100.00%2100.00%

#define spin_lock_nested(lock, subclass) \ do { \ raw_spin_lock_nested(spinlock_check(lock), subclass); \ } while (0) #define spin_lock_nest_lock(lock, nest_lock) \ do { \ raw_spin_lock_nest_lock(spinlock_check(lock), nest_lock); \ } while (0)
static __always_inline void spin_lock_irq(spinlock_t *lock) { raw_spin_lock_irq(&lock->rlock); }

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#define spin_lock_irqsave(lock, flags) \ do { \ raw_spin_lock_irqsave(spinlock_check(lock), flags); \ } while (0) #define spin_lock_irqsave_nested(lock, flags, subclass) \ do { \ raw_spin_lock_irqsave_nested(spinlock_check(lock), flags, subclass); \ } while (0)
static __always_inline void spin_unlock(spinlock_t *lock) { raw_spin_unlock(&lock->rlock); }

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Thomas Gleixner1894.74%150.00%
Denys Vlasenko15.26%150.00%
Total19100.00%2100.00%


static __always_inline void spin_unlock_bh(spinlock_t *lock) { raw_spin_unlock_bh(&lock->rlock); }

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Thomas Gleixner1894.74%150.00%
Denys Vlasenko15.26%150.00%
Total19100.00%2100.00%


static __always_inline void spin_unlock_irq(spinlock_t *lock) { raw_spin_unlock_irq(&lock->rlock); }

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Thomas Gleixner1894.74%150.00%
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Total19100.00%2100.00%


static __always_inline void spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags) { raw_spin_unlock_irqrestore(&lock->rlock, flags); }

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Total25100.00%2100.00%


static __always_inline int spin_trylock_bh(spinlock_t *lock) { return raw_spin_trylock_bh(&lock->rlock); }

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Thomas Gleixner1995.00%150.00%
Denys Vlasenko15.00%150.00%
Total20100.00%2100.00%


static __always_inline int spin_trylock_irq(spinlock_t *lock) { return raw_spin_trylock_irq(&lock->rlock); }

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Thomas Gleixner1995.00%150.00%
Denys Vlasenko15.00%150.00%
Total20100.00%2100.00%

#define spin_trylock_irqsave(lock, flags) \ ({ \ raw_spin_trylock_irqsave(spinlock_check(lock), flags); \ })
static __always_inline int spin_is_locked(spinlock_t *lock) { return raw_spin_is_locked(&lock->rlock); }

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Thomas Gleixner1995.00%150.00%
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Total20100.00%2100.00%


static __always_inline int spin_is_contended(spinlock_t *lock) { return raw_spin_is_contended(&lock->rlock); }

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Thomas Gleixner1995.00%150.00%
Denys Vlasenko15.00%150.00%
Total20100.00%2100.00%

#define assert_spin_locked(lock) assert_raw_spin_locked(&(lock)->rlock) /* * Pull the atomic_t declaration: * (asm-mips/atomic.h needs above definitions) */ #include <linux/atomic.h> /** * atomic_dec_and_lock - lock on reaching reference count zero * @atomic: the atomic counter * @lock: the spinlock in question * * Decrements @atomic by 1. If the result is 0, returns true and locks * @lock. Returns false for all other cases. */ extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock); #define atomic_dec_and_lock(atomic, lock) \ __cond_lock(lock, _atomic_dec_and_lock(atomic, lock)) #endif /* __LINUX_SPINLOCK_H */

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Thomas Gleixner47851.29%613.04%
Ingo Molnar10911.70%510.87%
Arjan van de Ven373.97%12.17%
Robert Love353.76%24.35%
Luca Barbieri353.76%12.17%
Linus Torvalds (pre-git)283.00%36.52%
Linus Torvalds242.58%36.52%
Zwane Mwaikambo232.47%12.17%
Heiko Carstens222.36%12.17%
Peter Zijlstra192.04%24.35%
David S. Miller181.93%12.17%
Andrew Morton171.82%24.35%
Will Deacon141.50%12.17%
Denys Vlasenko141.50%24.35%
James Morris141.50%12.17%
Kyle McMartin101.07%12.17%
Nicholas Piggin70.75%12.17%
Steven Rostedt50.54%12.17%
Jiri Olsa40.43%12.17%
David Howells40.43%24.35%
Bart Van Assche30.32%12.17%
Oleg Nesterov30.32%12.17%
Paul Gortmaker30.32%12.17%
Tom Rini20.21%12.17%
Lucas De Marchi10.11%12.17%
Arun Sharma10.11%12.17%
Greg Kroah-Hartman10.11%12.17%
Harvey Harrison10.11%12.17%
Total932100.00%46100.00%
Directory: include/linux
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