cregit-Linux how code gets into the kernel

Release 4.8 net/sunrpc/cache.c

Directory: net/sunrpc
/*
 * net/sunrpc/cache.c
 *
 * Generic code for various authentication-related caches
 * used by sunrpc clients and servers.
 *
 * Copyright (C) 2002 Neil Brown <neilb@cse.unsw.edu.au>
 *
 * Released under terms in GPL version 2.  See COPYING.
 *
 */

#include <linux/types.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/slab.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/kmod.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/ctype.h>
#include <linux/string_helpers.h>
#include <asm/uaccess.h>
#include <linux/poll.h>
#include <linux/seq_file.h>
#include <linux/proc_fs.h>
#include <linux/net.h>
#include <linux/workqueue.h>
#include <linux/mutex.h>
#include <linux/pagemap.h>
#include <asm/ioctls.h>
#include <linux/sunrpc/types.h>
#include <linux/sunrpc/cache.h>
#include <linux/sunrpc/stats.h>
#include <linux/sunrpc/rpc_pipe_fs.h>
#include "netns.h"


#define	 RPCDBG_FACILITY RPCDBG_CACHE

static bool cache_defer_req(struct cache_req *req, struct cache_head *item);
static void cache_revisit_request(struct cache_head *item);


static void cache_init(struct cache_head *h, struct cache_detail *detail) { time_t now = seconds_since_boot(); INIT_HLIST_NODE(&h->cache_list); h->flags = 0; kref_init(&h->ref); h->expiry_time = now + CACHE_NEW_EXPIRY; if (now <= detail->flush_time) /* ensure it isn't already expired */ now = detail->flush_time + 1; h->last_refresh = now; }

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adrian bunkadrian bunk11.33%114.29%
andi kleenandi kleen11.33%114.29%
Total75100.00%7100.00%


struct cache_head *sunrpc_cache_lookup(struct cache_detail *detail, struct cache_head *key, int hash) { struct cache_head *new = NULL, *freeme = NULL, *tmp = NULL; struct hlist_head *head; head = &detail->hash_table[hash]; read_lock(&detail->hash_lock); hlist_for_each_entry(tmp, head, cache_list) { if (detail->match(tmp, key)) { if (cache_is_expired(detail, tmp)) /* This entry is expired, we will discard it. */ break; cache_get(tmp); read_unlock(&detail->hash_lock); return tmp; } } read_unlock(&detail->hash_lock); /* Didn't find anything, insert an empty entry */ new = detail->alloc(); if (!new) return NULL; /* must fully initialise 'new', else * we might get lose if we need to * cache_put it soon. */ cache_init(new, detail); detail->init(new, key); write_lock(&detail->hash_lock); /* check if entry appeared while we slept */ hlist_for_each_entry(tmp, head, cache_list) { if (detail->match(tmp, key)) { if (cache_is_expired(detail, tmp)) { hlist_del_init(&tmp->cache_list); detail->entries --; freeme = tmp; break; } cache_get(tmp); write_unlock(&detail->hash_lock); cache_put(new, detail); return tmp; } } hlist_add_head(&new->cache_list, head); detail->entries++; cache_get(new); write_unlock(&detail->hash_lock); if (freeme) cache_put(freeme, detail); return new; }

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Total277100.00%5100.00%

EXPORT_SYMBOL_GPL(sunrpc_cache_lookup); static void cache_dequeue(struct cache_detail *detail, struct cache_head *ch);
static void cache_fresh_locked(struct cache_head *head, time_t expiry, struct cache_detail *detail) { time_t now = seconds_since_boot(); if (now <= detail->flush_time) /* ensure it isn't immediately treated as expired */ now = detail->flush_time + 1; head->expiry_time = expiry; head->last_refresh = now; smp_wmb(); /* paired with smp_rmb() in cache_is_valid() */ set_bit(CACHE_VALID, &head->flags); }

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Total68100.00%4100.00%


static void cache_fresh_unlocked(struct cache_head *head, struct cache_detail *detail) { if (test_and_clear_bit(CACHE_PENDING, &head->flags)) { cache_revisit_request(head); cache_dequeue(detail, head); } }

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struct cache_head *sunrpc_cache_update(struct cache_detail *detail, struct cache_head *new, struct cache_head *old, int hash) { /* The 'old' entry is to be replaced by 'new'. * If 'old' is not VALID, we update it directly, * otherwise we need to replace it */ struct cache_head *tmp; if (!test_bit(CACHE_VALID, &old->flags)) { write_lock(&detail->hash_lock); if (!test_bit(CACHE_VALID, &old->flags)) { if (test_bit(CACHE_NEGATIVE, &new->flags)) set_bit(CACHE_NEGATIVE, &old->flags); else detail->update(old, new); cache_fresh_locked(old, new->expiry_time, detail); write_unlock(&detail->hash_lock); cache_fresh_unlocked(old, detail); return old; } write_unlock(&detail->hash_lock); } /* We need to insert a new entry */ tmp = detail->alloc(); if (!tmp) { cache_put(old, detail); return NULL; } cache_init(tmp, detail); detail->init(tmp, old); write_lock(&detail->hash_lock); if (test_bit(CACHE_NEGATIVE, &new->flags)) set_bit(CACHE_NEGATIVE, &tmp->flags); else detail->update(tmp, new); hlist_add_head(&tmp->cache_list, &detail->hash_table[hash]); detail->entries++; cache_get(tmp); cache_fresh_locked(tmp, new->expiry_time, detail); cache_fresh_locked(old, 0, detail); write_unlock(&detail->hash_lock); cache_fresh_unlocked(tmp, detail); cache_fresh_unlocked(old, detail); cache_put(old, detail); return tmp; }

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EXPORT_SYMBOL_GPL(sunrpc_cache_update);
static int cache_make_upcall(struct cache_detail *cd, struct cache_head *h) { if (cd->cache_upcall) return cd->cache_upcall(cd, h); return sunrpc_cache_pipe_upcall(cd, h); }

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stanislav kinsburskystanislav kinsbursky820.00%133.33%
Total40100.00%3100.00%


static inline int cache_is_valid(struct cache_head *h) { if (!test_bit(CACHE_VALID, &h->flags)) return -EAGAIN; else { /* entry is valid */ if (test_bit(CACHE_NEGATIVE, &h->flags)) return -ENOENT; else { /* * In combination with write barrier in * sunrpc_cache_update, ensures that anyone * using the cache entry after this sees the * updated contents: */ smp_rmb(); return 0; } } }

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static int try_to_negate_entry(struct cache_detail *detail, struct cache_head *h) { int rv; write_lock(&detail->hash_lock); rv = cache_is_valid(h); if (rv == -EAGAIN) { set_bit(CACHE_NEGATIVE, &h->flags); cache_fresh_locked(h, seconds_since_boot()+CACHE_NEW_EXPIRY, detail); rv = -ENOENT; } write_unlock(&detail->hash_lock); cache_fresh_unlocked(h, detail); return rv; }

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j. bruce fieldsj. bruce fields7888.64%133.33%
neil brownneil brown1011.36%266.67%
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/* * This is the generic cache management routine for all * the authentication caches. * It checks the currency of a cache item and will (later) * initiate an upcall to fill it if needed. * * * Returns 0 if the cache_head can be used, or cache_puts it and returns * -EAGAIN if upcall is pending and request has been queued * -ETIMEDOUT if upcall failed or request could not be queue or * upcall completed but item is still invalid (implying that * the cache item has been replaced with a newer one). * -ENOENT if cache entry was negative */
int cache_check(struct cache_detail *detail, struct cache_head *h, struct cache_req *rqstp) { int rv; long refresh_age, age; /* First decide return status as best we can */ rv = cache_is_valid(h); /* now see if we want to start an upcall */ refresh_age = (h->expiry_time - h->last_refresh); age = seconds_since_boot() - h->last_refresh; if (rqstp == NULL) { if (rv == -EAGAIN) rv = -ENOENT; } else if (rv == -EAGAIN || (h->expiry_time != 0 && age > refresh_age/2)) { dprintk("RPC: Want update, refage=%ld, age=%ld\n", refresh_age, age); if (!test_and_set_bit(CACHE_PENDING, &h->flags)) { switch (cache_make_upcall(detail, h)) { case -EINVAL: rv = try_to_negate_entry(detail, h); break; case -EAGAIN: cache_fresh_unlocked(h, detail); break; } } } if (rv == -EAGAIN) { if (!cache_defer_req(rqstp, h)) { /* * Request was not deferred; handle it as best * we can ourselves: */ rv = cache_is_valid(h); if (rv == -EAGAIN) rv = -ETIMEDOUT; } } if (rv) cache_put(h, detail); return rv; }

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neil brownneil brown20594.04%861.54%
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chuck leverchuck lever10.46%17.69%
andi kleenandi kleen10.46%17.69%
Total218100.00%13100.00%

EXPORT_SYMBOL_GPL(cache_check); /* * caches need to be periodically cleaned. * For this we maintain a list of cache_detail and * a current pointer into that list and into the table * for that entry. * * Each time cache_clean is called it finds the next non-empty entry * in the current table and walks the list in that entry * looking for entries that can be removed. * * An entry gets removed if: * - The expiry is before current time * - The last_refresh time is before the flush_time for that cache * * later we might drop old entries with non-NEVER expiry if that table * is getting 'full' for some definition of 'full' * * The question of "how often to scan a table" is an interesting one * and is answered in part by the use of the "nextcheck" field in the * cache_detail. * When a scan of a table begins, the nextcheck field is set to a time * that is well into the future. * While scanning, if an expiry time is found that is earlier than the * current nextcheck time, nextcheck is set to that expiry time. * If the flush_time is ever set to a time earlier than the nextcheck * time, the nextcheck time is then set to that flush_time. * * A table is then only scanned if the current time is at least * the nextcheck time. * */ static LIST_HEAD(cache_list); static DEFINE_SPINLOCK(cache_list_lock); static struct cache_detail *current_detail; static int current_index; static void do_cache_clean(struct work_struct *work); static struct delayed_work cache_cleaner;
void sunrpc_init_cache_detail(struct cache_detail *cd) { rwlock_init(&cd->hash_lock); INIT_LIST_HEAD(&cd->queue); spin_lock(&cache_list_lock); cd->nextcheck = 0; cd->entries = 0; atomic_set(&cd->readers, 0); cd->last_close = 0; cd->last_warn = -1; list_add(&cd->others, &cache_list); spin_unlock(&cache_list_lock); /* start the cleaning process */ schedule_delayed_work(&cache_cleaner, 0); }

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neil brownneil brown1212.90%250.00%
Total93100.00%4100.00%

EXPORT_SYMBOL_GPL(sunrpc_init_cache_detail);
void sunrpc_destroy_cache_detail(struct cache_detail *cd) { cache_purge(cd); spin_lock(&cache_list_lock); write_lock(&cd->hash_lock); if (cd->entries) { write_unlock(&cd->hash_lock); spin_unlock(&cache_list_lock); goto out; } if (current_detail == cd) current_detail = NULL; list_del_init(&cd->others); write_unlock(&cd->hash_lock); spin_unlock(&cache_list_lock); if (list_empty(&cache_list)) { /* module must be being unloaded so its safe to kill the worker */ cancel_delayed_work_sync(&cache_cleaner); } return; out: printk(KERN_ERR "RPC: failed to unregister %s cache\n", cd->name); }

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neil brownneil brown5345.69%535.71%
j. bruce fieldsj. bruce fields3227.59%321.43%
trond myklebusttrond myklebust1815.52%214.29%
andrew mortonandrew morton65.17%17.14%
wang chenwang chen54.31%17.14%
denis v. lunevdenis v. lunev10.86%17.14%
kinglong meekinglong mee10.86%17.14%
Total116100.00%14100.00%

EXPORT_SYMBOL_GPL(sunrpc_destroy_cache_detail); /* clean cache tries to find something to clean * and cleans it. * It returns 1 if it cleaned something, * 0 if it didn't find anything this time * -1 if it fell off the end of the list. */
static int cache_clean(void) { int rv = 0; struct list_head *next; spin_lock(&cache_list_lock); /* find a suitable table if we don't already have one */ while (current_detail == NULL || current_index >= current_detail->hash_size) { if (current_detail) next = current_detail->others.next; else next = cache_list.next; if (next == &cache_list) { current_detail = NULL; spin_unlock(&cache_list_lock); return -1; } current_detail = list_entry(next, struct cache_detail, others); if (current_detail->nextcheck > seconds_since_boot()) current_index = current_detail->hash_size; else { current_index = 0; current_detail->nextcheck = seconds_since_boot()+30*60; } } /* find a non-empty bucket in the table */ while (current_detail && current_index < current_detail->hash_size && hlist_empty(&current_detail->hash_table[current_index])) current_index++; /* find a cleanable entry in the bucket and clean it, or set to next bucket */ if (current_detail && current_index < current_detail->hash_size) { struct cache_head *ch = NULL; struct cache_detail *d; struct hlist_head *head; struct hlist_node *tmp; write_lock(&current_detail->hash_lock); /* Ok, now to clean this strand */ head = &current_detail->hash_table[current_index]; hlist_for_each_entry_safe(ch, tmp, head, cache_list) { if (current_detail->nextcheck > ch->expiry_time) current_detail->nextcheck = ch->expiry_time+1; if (!cache_is_expired(current_detail, ch)) continue; hlist_del_init(&ch->cache_list); current_detail->entries--; rv = 1; break; } write_unlock(&current_detail->hash_lock); d = current_detail; if (!ch) current_index ++; spin_unlock(&cache_list_lock); if (ch) { set_bit(CACHE_CLEANED, &ch->flags); cache_fresh_unlocked(ch, d); cache_put(ch, d); } } else spin_unlock(&cache_list_lock); return rv; }

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neil brownneil brown24272.89%1047.62%
kinglong meekinglong mee329.64%14.76%
andrew mortonandrew morton298.73%314.29%
j. bruce fieldsj. bruce fields236.93%419.05%
trond myklebusttrond myklebust41.20%29.52%
andi kleenandi kleen20.60%14.76%
Total332100.00%21100.00%

/* * We want to regularly clean the cache, so we need to schedule some work ... */
static void do_cache_clean(struct work_struct *work) { int delay = 5; if (cache_clean() == -1) delay = round_jiffies_relative(30*HZ); if (list_empty(&cache_list)) delay = 0; if (delay) schedule_delayed_work(&cache_cleaner, delay); }

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anton blanchardanton blanchard35.26%120.00%
david howellsdavid howells35.26%120.00%
adrian bunkadrian bunk11.75%120.00%
Total57100.00%5100.00%

/* * Clean all caches promptly. This just calls cache_clean * repeatedly until we are sure that every cache has had a chance to * be fully cleaned */
void cache_flush(void) { while (cache_clean() != -1) cond_resched(); while (cache_clean() != -1) cond_resched(); }

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EXPORT_SYMBOL_GPL(cache_flush);
void cache_purge(struct cache_detail *detail) { time_t now = seconds_since_boot(); if (detail->flush_time >= now) now = detail->flush_time + 1; /* 'now' is the maximum value any 'last_refresh' can have */ detail->flush_time = now; detail->nextcheck = seconds_since_boot(); cache_flush(); }

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EXPORT_SYMBOL_GPL(cache_purge); /* * Deferral and Revisiting of Requests. * * If a cache lookup finds a pending entry, we * need to defer the request and revisit it later. * All deferred requests are stored in a hash table, * indexed by "struct cache_head *". * As it may be wasteful to store a whole request * structure, we allow the request to provide a * deferred form, which must contain a * 'struct cache_deferred_req' * This cache_deferred_req contains a method to allow * it to be revisited when cache info is available */ #define DFR_HASHSIZE (PAGE_SIZE/sizeof(struct list_head)) #define DFR_HASH(item) ((((long)item)>>4 ^ (((long)item)>>13)) % DFR_HASHSIZE) #define DFR_MAX 300 /* ??? */ static DEFINE_SPINLOCK(cache_defer_lock); static LIST_HEAD(cache_defer_list); static struct hlist_head cache_defer_hash[DFR_HASHSIZE]; static int cache_defer_cnt;
static void __unhash_deferred_req(struct cache_deferred_req *dreq) { hlist_del_init(&dreq->hash); if (!list_empty(&dreq->recent)) { list_del_init(&dreq->recent); cache_defer_cnt--; } }

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adrian bunkadrian bunk12.33%120.00%
Total43100.00%5100.00%


static void __hash_deferred_req(struct cache_deferred_req *dreq, struct cache_head *item) { int hash = DFR_HASH(item); INIT_LIST_HEAD(&dreq->recent); hlist_add_head(&dreq->hash, &cache_defer_hash[hash]); }

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j. bruce fieldsj. bruce fields2554.35%114.29%
neil brownneil brown1941.30%571.43%
andrew mortonandrew morton24.35%114.29%
Total46100.00%7100.00%


static void setup_deferral(struct cache_deferred_req *dreq, struct cache_head *item, int count_me) { dreq->item = item; spin_lock(&cache_defer_lock); __hash_deferred_req(dreq, item); if (count_me) { cache_defer_cnt++; list_add(&dreq->recent, &cache_defer_list); } spin_unlock(&cache_defer_lock); }

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neil brownneil brown5484.38%450.00%
j. bruce fieldsj. bruce fields57.81%225.00%
andrew mortonandrew morton46.25%112.50%
adrian bunkadrian bunk11.56%112.50%
Total64100.00%8100.00%

struct thread_deferred_req { struct cache_deferred_req handle; struct completion completion; };
static void cache_restart_thread(struct cache_deferred_req *dreq, int too_many) { struct thread_deferred_req *dr = container_of(dreq, struct thread_deferred_req, handle); complete(&dr->completion); }

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neil brownneil brown1232.43%480.00%
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static void cache_wait_req(struct cache_req *req, struct cache_head *item) { struct thread_deferred_req sleeper; struct cache_deferred_req *dreq = &sleeper.handle; sleeper.completion = COMPLETION_INITIALIZER_ONSTACK(sleeper.completion); dreq->revisit = cache_restart_thread; setup_deferral(dreq, item, 0); if (!test_bit(CACHE_PENDING, &item->flags) || wait_for_completion_interruptible_timeout( &sleeper.completion, req->thread_wait) <= 0) { /* The completion wasn't completed, so we need * to clean up */ spin_lock(&cache_defer_lock); if (!hlist_unhashed(&sleeper.handle.hash)) { __unhash_deferred_req(&sleeper.handle); spin_unlock(&cache_defer_lock); } else { /* cache_revisit_request already removed * this from the hash table, but hasn't * called ->revisit yet. It will very soon * and we need to wait for it. */ spin_unlock(&cache_defer_lock); wait_for_completion(&sleeper.completion); } } }

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j. bruce fieldsj. bruce fields5438.85%228.57%
Total139100.00%7100.00%


static void cache_limit_defers(void) { /* Make sure we haven't exceed the limit of allowed deferred * requests. */ struct cache_deferred_req *discard = NULL; if (cache_defer_cnt <= DFR_MAX) return; spin_lock(&cache_defer_lock); /* Consider removing either the first or the last */ if (cache_defer_cnt > DFR_MAX) { if (prandom_u32() & 1) discard = list_entry(cache_defer_list.next, struct cache_deferred_req, recent); else discard = list_entry(cache_defer_list.prev, struct cache_deferred_req, recent); __unhash_deferred_req(discard); } spin_unlock(&cache_defer_lock); if (discard) discard->revisit(discard, 1); }

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j. bruce fieldsj. bruce fields1919.39%112.50%
andrew mortonandrew morton44.08%112.50%
aruna-hewapathiranearuna-hewapathirane11.02%112.50%
Total98100.00%8100.00%

/* Return true if and only if a deferred request is queued. */
static bool cache_defer_req(struct cache_req *req, struct cache_head *item) { struct cache_deferred_req *dreq; if (req->thread_wait) { cache_wait_req(req, item); if (!test_bit(CACHE_PENDING, &item->flags)) return false; } dreq = req->defer(req); if (dreq == NULL) return false; setup_deferral(dreq, item, 1); if (!test_bit(CACHE_PENDING, &item->flags)) /* Bit could have been cleared before we managed to * set up the deferral, so need to revisit just in case */ cache_revisit_request(item); cache_limit_defers(); return true; }

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neil brownneil brown6764.42%675.00%
j. bruce fieldsj. bruce fields3735.58%225.00%
Total104100.00%8100.00%


static void cache_revisit_request(struct cache_head *item) { struct cache_deferred_req *dreq; struct list_head pending; struct hlist_node *tmp; int hash = DFR_HASH(item); INIT_LIST_HEAD(&pending); spin_lock(&cache_defer_lock); hlist_for_each_entry_safe(dreq, tmp, &cache_defer_hash[hash], hash) if (dreq->item == item) { __unhash_deferred_req(dreq); list_add(&dreq->recent, &pending); } spin_unlock(&cache_defer_lock); while (!list_empty(&pending)) { dreq = list_entry(pending.next, struct cache_deferred_req, recent); list_del_init(&dreq->recent);