/* * 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 = READ_ONCE(lock->owner); if (owner == SPINLOCK_OWNER_INIT) owner = NULL; 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, READ_ONCE(lock->magic), owner ? owner->comm : "<none>", owner ? task_pid_nr(owner) : -1, READ_ONCE(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(READ_ONCE(lock->magic) != SPINLOCK_MAGIC, lock, "bad magic"); SPIN_BUG_ON(READ_ONCE(lock->owner) == current, lock, "recursion"); SPIN_BUG_ON(READ_ONCE(lock->owner_cpu) == raw_smp_processor_id(), lock, "cpu recursion"); } static inline void debug_spin_lock_after(raw_spinlock_t *lock) { WRITE_ONCE(lock->owner_cpu, raw_smp_processor_id()); WRITE_ONCE(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"); WRITE_ONCE(lock->owner, SPINLOCK_OWNER_INIT); WRITE_ONCE(lock->owner_cpu, -1); } /* * We are now relying on the NMI watchdog to detect lockup instead of doing * the detection here with an unfair lock which can cause problem of its own. */ void do_raw_spin_lock(raw_spinlock_t *lock) { debug_spin_lock_before(lock); arch_spin_lock(&lock->raw_lock); mmiowb_spin_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) { mmiowb_spin_lock(); 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) { mmiowb_spin_unlock(); 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) 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) { WRITE_ONCE(lock->owner_cpu, raw_smp_processor_id()); WRITE_ONCE(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"); WRITE_ONCE(lock->owner, SPINLOCK_OWNER_INIT); WRITE_ONCE(lock->owner_cpu, -1); } 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); }