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
 111        for (i = 0; i < loops; i++) {
 112                if (arch_spin_trylock(&lock->raw_lock))
 113                        return;
 114                __delay(1);
 115        }
 116        /* lockup suspected: */
 117        spin_dump(lock, "lockup suspected");
 118#ifdef CONFIG_SMP
 119        trigger_all_cpu_backtrace();
 120#endif
 121
 122        /*
 123         * The trylock above was causing a livelock.  Give the lower level arch
 124         * specific lock code a chance to acquire the lock. We have already
 125         * printed a warning/backtrace at this point. The non-debug arch
 126         * specific code might actually succeed in acquiring the lock.  If it is
 127         * not successful, the end-result is the same - there is no forward
 128         * progress.
 129         */
 130        arch_spin_lock(&lock->raw_lock);
 131}
 132
 133void do_raw_spin_lock(raw_spinlock_t *lock)
 134{
 135        debug_spin_lock_before(lock);
 136        if (unlikely(!arch_spin_trylock(&lock->raw_lock)))
 137                __spin_lock_debug(lock);
 138        debug_spin_lock_after(lock);
 139}
 140
 141int do_raw_spin_trylock(raw_spinlock_t *lock)
 142{
 143        int ret = arch_spin_trylock(&lock->raw_lock);
 144
 145        if (ret)
 146                debug_spin_lock_after(lock);
 147#ifndef CONFIG_SMP
 148        /*
 149         * Must not happen on UP:
 150         */
 151        SPIN_BUG_ON(!ret, lock, "trylock failure on UP");
 152#endif
 153        return ret;
 154}
 155
 156void do_raw_spin_unlock(raw_spinlock_t *lock)
 157{
 158        debug_spin_unlock(lock);
 159        arch_spin_unlock(&lock->raw_lock);
 160}
 161
 162static void rwlock_bug(rwlock_t *lock, const char *msg)
 163{
 164        if (!debug_locks_off())
 165                return;
 166
 167        printk(KERN_EMERG "BUG: rwlock %s on CPU#%d, %s/%d, %p\n",
 168                msg, raw_smp_processor_id(), current->comm,
 169                task_pid_nr(current), lock);
 170        dump_stack();
 171}
 172
 173#define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg)
 174
 175#if 0           /* __write_lock_debug() can lock up - maybe this can too? */
 176static void __read_lock_debug(rwlock_t *lock)
 177{
 178        u64 i;
 179        u64 loops = loops_per_jiffy * HZ;
 180        int print_once = 1;
 181
 182        for (;;) {
 183                for (i = 0; i < loops; i++) {
 184                        if (arch_read_trylock(&lock->raw_lock))
 185                                return;
 186                        __delay(1);
 187                }
 188                /* lockup suspected: */
 189                if (print_once) {
 190                        print_once = 0;
 191                        printk(KERN_EMERG "BUG: read-lock lockup on CPU#%d, "
 192                                        "%s/%d, %p\n",
 193                                raw_smp_processor_id(), current->comm,
 194                                current->pid, lock);
 195                        dump_stack();
 196                }
 197        }
 198}
 199#endif
 200
 201void do_raw_read_lock(rwlock_t *lock)
 202{
 203        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 204        arch_read_lock(&lock->raw_lock);
 205}
 206
 207int do_raw_read_trylock(rwlock_t *lock)
 208{
 209        int ret = arch_read_trylock(&lock->raw_lock);
 210
 211#ifndef CONFIG_SMP
 212        /*
 213         * Must not happen on UP:
 214         */
 215        RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
 216#endif
 217        return ret;
 218}
 219
 220void do_raw_read_unlock(rwlock_t *lock)
 221{
 222        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 223        arch_read_unlock(&lock->raw_lock);
 224}
 225
 226static inline void debug_write_lock_before(rwlock_t *lock)
 227{
 228        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 229        RWLOCK_BUG_ON(lock->owner == current, lock, "recursion");
 230        RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
 231                                                        lock, "cpu recursion");
 232}
 233
 234static inline void debug_write_lock_after(rwlock_t *lock)
 235{
 236        lock->owner_cpu = raw_smp_processor_id();
 237        lock->owner = current;
 238}
 239
 240static inline void debug_write_unlock(rwlock_t *lock)
 241{
 242        RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 243        RWLOCK_BUG_ON(lock->owner != current, lock, "wrong owner");
 244        RWLOCK_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
 245                                                        lock, "wrong CPU");
 246        lock->owner = SPINLOCK_OWNER_INIT;
 247        lock->owner_cpu = -1;
 248}
 249
 250#if 0           /* This can cause lockups */
 251static void __write_lock_debug(rwlock_t *lock)
 252{
 253        u64 i;
 254        u64 loops = loops_per_jiffy * HZ;
 255        int print_once = 1;
 256
 257        for (;;) {
 258                for (i = 0; i < loops; i++) {
 259                        if (arch_write_trylock(&lock->raw_lock))
 260                                return;
 261                        __delay(1);
 262                }
 263                /* lockup suspected: */
 264                if (print_once) {
 265                        print_once = 0;
 266                        printk(KERN_EMERG "BUG: write-lock lockup on CPU#%d, "
 267                                        "%s/%d, %p\n",
 268                                raw_smp_processor_id(), current->comm,
 269                                current->pid, lock);
 270                        dump_stack();
 271                }
 272        }
 273}
 274#endif
 275
 276void do_raw_write_lock(rwlock_t *lock)
 277{
 278        debug_write_lock_before(lock);
 279        arch_write_lock(&lock->raw_lock);
 280        debug_write_lock_after(lock);
 281}
 282
 283int do_raw_write_trylock(rwlock_t *lock)
 284{
 285        int ret = arch_write_trylock(&lock->raw_lock);
 286
 287        if (ret)
 288                debug_write_lock_after(lock);
 289#ifndef CONFIG_SMP
 290        /*
 291         * Must not happen on UP:
 292         */
 293        RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
 294#endif
 295        return ret;
 296}
 297
 298void do_raw_write_unlock(rwlock_t *lock)
 299{
 300        debug_write_unlock(lock);
 301        arch_write_unlock(&lock->raw_lock);
 302}
 303
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