/* * Copyright 2005, Red Hat, Inc., Ingo Molnar * Released under the General Public License (GPL). * * This file contains the spinlock/rwlock implementations for * DEBUG_SPINLOCK. */ #include <linux/spinlock.h> #include <linux/nmi.h> #include <linux/interrupt.h> #include <linux/debug_locks.h> #include <linux/delay.h> #include <linux/export.h> void __raw_spin_lock_init(raw_spinlock_t *lock, const char *name, struct lock_class_key *key) { #ifdef CONFIG_DEBUG_LOCK_ALLOC /* * Make sure we are not reinitializing a held lock: */ debug_check_no_locks_freed((void *)lock, sizeof(*lock)); lockdep_init_map(&lock->dep_map, name, key, 0); #endif lock->raw_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; lock->magic = SPINLOCK_MAGIC; lock->owner = SPINLOCK_OWNER_INIT; lock->owner_cpu = -1; } EXPORT_SYMBOL(__raw_spin_lock_init); void __rwlock_init(rwlock_t *lock, const char *name, struct lock_class_key *key) { #ifdef CONFIG_DEBUG_LOCK_ALLOC /* * Make sure we are not reinitializing a held lock: */ debug_check_no_locks_freed((void *)lock, sizeof(*lock)); lockdep_init_map(&lock->dep_map, name, key, 0); #endif lock->raw_lock = (arch_rwlock_t) __ARCH_RW_LOCK_UNLOCKED; lock->magic = RWLOCK_MAGIC; lock->owner = SPINLOCK_OWNER_INIT; lock->owner_cpu = -1; } EXPORT_SYMBOL(__rwlock_init); static void spin_dump(raw_spinlock_t *lock, const char *msg) { struct task_struct *owner = NULL; if (lock->owner && lock->owner != SPINLOCK_OWNER_INIT) owner = lock->owner; printk(KERN_EMERG "BUG: spinlock %s on CPU#%d, %s/%d\n", msg, raw_smp_processor_id(), current->comm, task_pid_nr(current)); printk(KERN_EMERG " lock: %pS, .magic: %08x, .owner: %s/%d, " ".owner_cpu: %d\n", lock, lock->magic, owner ? owner->comm : "<none>", owner ? task_pid_nr(owner) : -1, lock->owner_cpu); dump_stack(); } static void spin_bug(raw_spinlock_t *lock, const char *msg) { if (!debug_locks_off()) return; spin_dump(lock, msg); } #define SPIN_BUG_ON(cond, lock, msg) if (unlikely(cond)) spin_bug(lock, msg) static inline void debug_spin_lock_before(raw_spinlock_t *lock) { SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic"); SPIN_BUG_ON(lock->owner == current, lock, "recursion"); SPIN_BUG_ON(lock->owner_cpu == raw_smp_processor_id(), lock, "cpu recursion"); } static inline void debug_spin_lock_after(raw_spinlock_t *lock) { lock->owner_cpu = raw_smp_processor_id(); lock->owner = current; } static inline void debug_spin_unlock(raw_spinlock_t *lock) { SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic"); SPIN_BUG_ON(!raw_spin_is_locked(lock), lock, "already unlocked"); SPIN_BUG_ON(lock->owner != current, lock, "wrong owner"); SPIN_BUG_ON(lock->owner_cpu != raw_smp_processor_id(), lock, "wrong CPU"); lock->owner = SPINLOCK_OWNER_INIT; lock->owner_cpu = -1; } static void __spin_lock_debug(raw_spinlock_t *lock) { u64 i; u64 loops = loops_per_jiffy * HZ; for (i = 0; i < loops; i++) { if (arch_spin_trylock(&lock->raw_lock)) return; __delay(1); } /* lockup suspected: */ spin_dump(lock, "lockup suspected"); #ifdef CONFIG_SMP trigger_all_cpu_backtrace(); #endif /* * The trylock above was causing a livelock. Give the lower level arch * specific lock code a chance to acquire the lock. We have already * printed a warning/backtrace at this point. The non-debug arch * specific code might actually succeed in acquiring the lock. If it is * not successful, the end-result is the same - there is no forward * progress. */ arch_spin_lock(&lock->raw_lock); } void do_raw_spin_lock(raw_spinlock_t *lock) { debug_spin_lock_before(lock); if (unlikely(!arch_spin_trylock(&lock->raw_lock))) __spin_lock_debug(lock); debug_spin_lock_after(lock); } int do_raw_spin_trylock(raw_spinlock_t *lock) { int ret = arch_spin_trylock(&lock->raw_lock); if (ret) debug_spin_lock_after(lock); #ifndef CONFIG_SMP /* * Must not happen on UP: */ SPIN_BUG_ON(!ret, lock, "trylock failure on UP"); #endif return ret; } void do_raw_spin_unlock(raw_spinlock_t *lock) { debug_spin_unlock(lock); arch_spin_unlock(&lock->raw_lock); } static void rwlock_bug(rwlock_t *lock, const char *msg) { if (!debug_locks_off()) return; printk(KERN_EMERG "BUG: rwlock %s on CPU#%d, %s/%d, %p\n", msg, raw_smp_processor_id(), current->comm, task_pid_nr(current), lock); dump_stack(); } #define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg) #if 0 /* __write_lock_debug() can lock up - maybe this can too? */ static void __read_lock_debug(rwlock_t *lock) { u64 i; u64 loops = loops_per_jiffy * HZ; int print_once = 1; for (;;) { for (i = 0; i < loops; i++) { if (arch_read_trylock(&lock->raw_lock)) return; __delay(1); } /* lockup suspected: */ if (print_once) { print_once = 0; printk(KERN_EMERG "BUG: read-lock lockup on CPU#%d, " "%s/%d, %p\n", raw_smp_processor_id(), current->comm, current->pid, lock); dump_stack(); } } } #endif void do_raw_read_lock(rwlock_t *lock) { RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic"); arch_read_lock(&lock->raw_lock); } int do_raw_read_trylock(rwlock_t *lock) { int ret = arch_read_trylock(&lock->raw_lock); #ifndef CONFIG_SMP /* * Must not happen on UP: */ RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP"); #endif return ret; } void do_raw_read_unlock(rwlock_t *lock) { RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic"); arch_read_unlock(&lock->raw_lock); } static inline void debug_write_lock_before(rwlock_t *lock) { RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic"); RWLOCK_BUG_ON(lock->owner == current, lock, "recursion"); RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(), lock, "cpu recursion"); } static inline void debug_write_lock_after(rwlock_t *lock) { lock->owner_cpu = raw_smp_processor_id(); lock->owner = current; } static inline void debug_write_unlock(rwlock_t *lock) { RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic"); RWLOCK_BUG_ON(lock->owner != current, lock, "wrong owner"); RWLOCK_BUG_ON(lock->owner_cpu != raw_smp_processor_id(), lock, "wrong CPU"); lock->owner = SPINLOCK_OWNER_INIT; lock->owner_cpu = -1; } #if 0 /* This can cause lockups */ static void __write_lock_debug(rwlock_t *lock) { u64 i; u64 loops = loops_per_jiffy * HZ; int print_once = 1; for (;;) { for (i = 0; i < loops; i++) { if (arch_write_trylock(&lock->raw_lock)) return; __delay(1); } /* lockup suspected: */ if (print_once) { print_once = 0; printk(KERN_EMERG "BUG: write-lock lockup on CPU#%d, " "%s/%d, %p\n", raw_smp_processor_id(), current->comm, current->pid, lock); dump_stack(); } } } #endif void do_raw_write_lock(rwlock_t *lock) { debug_write_lock_before(lock); arch_write_lock(&lock->raw_lock); debug_write_lock_after(lock); } int do_raw_write_trylock(rwlock_t *lock) { int ret = arch_write_trylock(&lock->raw_lock); if (ret) debug_write_lock_after(lock); #ifndef CONFIG_SMP /* * Must not happen on UP: */ RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP"); #endif return ret; } void do_raw_write_unlock(rwlock_t *lock) { debug_write_unlock(lock); arch_write_unlock(&lock->raw_lock); }