linux/lib/spinlock_debug.c
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   1/*
   2 * Copyright 2005, Red Hat, Inc., Ingo Molnar
   3 * Released under the General Public License (GPL).
   4 *
   5 * This file contains the spinlock/rwlock implementations for
   6 * DEBUG_SPINLOCK.
   7 */
   8
   9#include <linux/spinlock.h>
  10#include <linux/nmi.h>
  11#include <linux/interrupt.h>
  12#include <linux/debug_locks.h>
  13#include <linux/delay.h>
  14#include <linux/export.h>
  15
  16void __raw_spin_lock_init(raw_spinlock_t *lock, const char *name,
  17                          struct lock_class_key *key)
  18{
  19#ifdef CONFIG_DEBUG_LOCK_ALLOC
  20        /*
  21         * Make sure we are not reinitializing a held lock:
  22         */
  23        debug_check_no_locks_freed((void *)lock, sizeof(*lock));
  24        lockdep_init_map(&lock->dep_map, name, key, 0);
  25#endif
  26        lock->raw_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
  27        lock->magic = SPINLOCK_MAGIC;
  28        lock->owner = SPINLOCK_OWNER_INIT;
  29        lock->owner_cpu = -1;
  30}
  31
  32EXPORT_SYMBOL(__raw_spin_lock_init);
  33
  34void __rwlock_init(rwlock_t *lock, const char *name,
  35                   struct lock_class_key *key)
  36{
  37#ifdef CONFIG_DEBUG_LOCK_ALLOC
  38        /*
  39         * Make sure we are not reinitializing a held lock:
  40         */
  41        debug_check_no_locks_freed((void *)lock, sizeof(*lock));
  42        lockdep_init_map(&lock->dep_map, name, key, 0);
  43#endif
  44        lock->raw_lock = (arch_rwlock_t) __ARCH_RW_LOCK_UNLOCKED;
  45        lock->magic = RWLOCK_MAGIC;
  46        lock->owner = SPINLOCK_OWNER_INIT;
  47        lock->owner_cpu = -1;
  48}
  49
  50EXPORT_SYMBOL(__rwlock_init);
  51
  52static void spin_dump(raw_spinlock_t *lock, const char *msg)
  53{
  54        struct task_struct *owner = NULL;
  55
  56        if (lock->owner && lock->owner != SPINLOCK_OWNER_INIT)
  57                owner = lock->owner;
  58        printk(KERN_EMERG "BUG: spinlock %s on CPU#%d, %s/%d\n",
  59                msg, raw_smp_processor_id(),
  60                current->comm, task_pid_nr(current));
  61        printk(KERN_EMERG " lock: %pS, .magic: %08x, .owner: %s/%d, "
  62                        ".owner_cpu: %d\n",
  63                lock, lock->magic,
  64                owner ? owner->comm : "<none>",
  65                owner ? task_pid_nr(owner) : -1,
  66                lock->owner_cpu);
  67        dump_stack();
  68}
  69
  70static void spin_bug(raw_spinlock_t *lock, const char *msg)
  71{
  72        if (!debug_locks_off())
  73                return;
  74
  75        spin_dump(lock, msg);
  76}
  77
  78#define SPIN_BUG_ON(cond, lock, msg) if (unlikely(cond)) spin_bug(lock, msg)
  79
  80static inline void
  81debug_spin_lock_before(raw_spinlock_t *lock)
  82{
  83        SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
  84        SPIN_BUG_ON(lock->owner == current, lock, "recursion");
  85        SPIN_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
  86                                                        lock, "cpu recursion");
  87}
  88
  89static inline void debug_spin_lock_after(raw_spinlock_t *lock)
  90{
  91        lock->owner_cpu = raw_smp_processor_id();
  92        lock->owner = current;
  93}
  94
  95static inline void debug_spin_unlock(raw_spinlock_t *lock)
  96{
  97        SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
  98        SPIN_BUG_ON(!raw_spin_is_locked(lock), lock, "already unlocked");
  99        SPIN_BUG_ON(lock->owner != current, lock, "wrong owner");
 100        SPIN_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
 101                                                        lock, "wrong CPU");
 102        lock->owner = SPINLOCK_OWNER_INIT;
 103        lock->owner_cpu = -1;
 104}
 105
 106static void __spin_lock_debug(raw_spinlock_t *lock)
 107{
 108        u64 i;
 109        u64 loops = loops_per_jiffy * HZ;
 110        int print_once = 1;
 111
 112        for (;;) {
 113                for (i = 0; i < loops; i++) {
 114                        if (arch_spin_trylock(&lock->raw_lock))
 115                                return;
 116                        __delay(1);
 117                }
 118                /* lockup suspected: */
 119                if (print_once) {
 120                        print_once = 0;
 121                        spin_dump(lock, "lockup suspected");
 122#ifdef CONFIG_SMP
 123                        trigger_all_cpu_backtrace();
 124#endif
 125                }
 126        }
 127}
 128
 129void do_raw_spin_lock(raw_spinlock_t *lock)
 130{
 131        debug_spin_lock_before(lock);
 132        if (unlikely(!arch_spin_trylock(&lock->raw_lock)))
 133                __spin_lock_debug(lock);
 134        debug_spin_lock_after(lock);
 135}
 136
 137int do_raw_spin_trylock(raw_spinlock_t *lock)
 138{
 139        int ret = arch_spin_trylock(&lock->raw_lock);
 140
 141        if (ret)
 142                debug_spin_lock_after(lock);
 143#ifndef CONFIG_SMP
 144        /*
 145         * Must not happen on UP:
 146         */
 147        SPIN_BUG_ON(!ret, lock, "trylock failure on UP");
 148#endif
 149        return ret;
 150}
 151
 152void do_raw_spin_unlock(raw_spinlock_t *lock)
 153{
 154        debug_spin_unlock(lock);
 155        arch_spin_unlock(&lock->raw_lock);
 156}
 157
 158static void rwlock_bug(rwlock_t *lock, const char *msg)
 159{
 160        if (!debug_locks_off())
 161                return;
 162
 163        printk(KERN_EMERG "BUG: rwlock %s on CPU#%d, %s/%d, %p\n",
 164                msg, raw_smp_processor_id(), current->comm,
 165                task_pid_nr(current), lock);
 166        dump_stack();
 167}
 168
 169#define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg)
 170
 171#if 0           /* __write_lock_debug() can lock up - maybe this can too? */
 172static void __read_lock_debug(rwlock_t *lock)
 173{
 174        u64 i;
 175        u64 loops = loops_per_jiffy * HZ;
 176        int print_once = 1;
 177
 178        for (;;) {
 179                for (i = 0; i < loops; i++) {
 180                        if (arch_read_trylock(&lock->raw_lock))
 181                                return;
 182                        __delay(1);
 183                }
 184                /* lockup suspected: */
 185                if (print_once) {
 186                        print_once = 0;
 187                        printk(KERN_EMERG "BUG: read-lock lockup on CPU#%d, "
 188                                        "%s/%d, %p\n",
 189                                raw_smp_processor_id(), current->comm,
 190                                current->pid, lock);
 191                        dump_stack();
 192                }
 193        }
 194}
 195#endif
 196
 197void do_raw_read_lock(rwlock_t *lock)
 198{
 199        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 200        arch_read_lock(&lock->raw_lock);
 201}
 202
 203int do_raw_read_trylock(rwlock_t *lock)
 204{
 205        int ret = arch_read_trylock(&lock->raw_lock);
 206
 207#ifndef CONFIG_SMP
 208        /*
 209         * Must not happen on UP:
 210         */
 211        RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
 212#endif
 213        return ret;
 214}
 215
 216void do_raw_read_unlock(rwlock_t *lock)
 217{
 218        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 219        arch_read_unlock(&lock->raw_lock);
 220}
 221
 222static inline void debug_write_lock_before(rwlock_t *lock)
 223{
 224        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 225        RWLOCK_BUG_ON(lock->owner == current, lock, "recursion");
 226        RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
 227                                                        lock, "cpu recursion");
 228}
 229
 230static inline void debug_write_lock_after(rwlock_t *lock)
 231{
 232        lock->owner_cpu = raw_smp_processor_id();
 233        lock->owner = current;
 234}
 235
 236static inline void debug_write_unlock(rwlock_t *lock)
 237{
 238        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 239        RWLOCK_BUG_ON(lock->owner != current, lock, "wrong owner");
 240        RWLOCK_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
 241                                                        lock, "wrong CPU");
 242        lock->owner = SPINLOCK_OWNER_INIT;
 243        lock->owner_cpu = -1;
 244}
 245
 246#if 0           /* This can cause lockups */
 247static void __write_lock_debug(rwlock_t *lock)
 248{
 249        u64 i;
 250        u64 loops = loops_per_jiffy * HZ;
 251        int print_once = 1;
 252
 253        for (;;) {
 254                for (i = 0; i < loops; i++) {
 255                        if (arch_write_trylock(&lock->raw_lock))
 256                                return;
 257                        __delay(1);
 258                }
 259                /* lockup suspected: */
 260                if (print_once) {
 261                        print_once = 0;
 262                        printk(KERN_EMERG "BUG: write-lock lockup on CPU#%d, "
 263                                        "%s/%d, %p\n",
 264                                raw_smp_processor_id(), current->comm,
 265                                current->pid, lock);
 266                        dump_stack();
 267                }
 268        }
 269}
 270#endif
 271
 272void do_raw_write_lock(rwlock_t *lock)
 273{
 274        debug_write_lock_before(lock);
 275        arch_write_lock(&lock->raw_lock);
 276        debug_write_lock_after(lock);
 277}
 278
 279int do_raw_write_trylock(rwlock_t *lock)
 280{
 281        int ret = arch_write_trylock(&lock->raw_lock);
 282
 283        if (ret)
 284                debug_write_lock_after(lock);
 285#ifndef CONFIG_SMP
 286        /*
 287         * Must not happen on UP:
 288         */
 289        RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
 290#endif
 291        return ret;
 292}
 293
 294void do_raw_write_unlock(rwlock_t *lock)
 295{
 296        debug_write_unlock(lock);
 297        arch_write_unlock(&lock->raw_lock);
 298}
 299
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