diff options
| -rw-r--r-- | include/linux/mutex.h | 2 | ||||
| -rw-r--r-- | include/linux/mutex_types.h | 2 | ||||
| -rw-r--r-- | kernel/locking/mutex-debug.c | 5 | ||||
| -rw-r--r-- | kernel/locking/mutex.c | 49 | ||||
| -rw-r--r-- | kernel/locking/ww_mutex.h | 25 |
5 files changed, 37 insertions, 46 deletions
diff --git a/include/linux/mutex.h b/include/linux/mutex.h index 2f648ee204e7..c471b129f703 100644 --- a/include/linux/mutex.h +++ b/include/linux/mutex.h @@ -79,7 +79,7 @@ do { \ #define __MUTEX_INITIALIZER(lockname) \ { .owner = ATOMIC_LONG_INIT(0) \ , .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(lockname.wait_lock) \ - , .wait_list = LIST_HEAD_INIT(lockname.wait_list) \ + , .first_waiter = NULL \ __DEBUG_MUTEX_INITIALIZER(lockname) \ __DEP_MAP_MUTEX_INITIALIZER(lockname) } diff --git a/include/linux/mutex_types.h b/include/linux/mutex_types.h index 80975935ec48..a8f119f81177 100644 --- a/include/linux/mutex_types.h +++ b/include/linux/mutex_types.h @@ -44,7 +44,7 @@ context_lock_struct(mutex) { #ifdef CONFIG_MUTEX_SPIN_ON_OWNER struct optimistic_spin_queue osq; /* Spinner MCS lock */ #endif - struct list_head wait_list; + struct mutex_waiter *first_waiter; #ifdef CONFIG_DEBUG_MUTEXES void *magic; #endif diff --git a/kernel/locking/mutex-debug.c b/kernel/locking/mutex-debug.c index 2c6b02d4699b..94930d506bcf 100644 --- a/kernel/locking/mutex-debug.c +++ b/kernel/locking/mutex-debug.c @@ -37,9 +37,8 @@ void debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter) void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter) { lockdep_assert_held(&lock->wait_lock); - DEBUG_LOCKS_WARN_ON(list_empty(&lock->wait_list)); + DEBUG_LOCKS_WARN_ON(!lock->first_waiter); DEBUG_LOCKS_WARN_ON(waiter->magic != waiter); - DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list)); } void debug_mutex_free_waiter(struct mutex_waiter *waiter) @@ -62,7 +61,6 @@ void debug_mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter, { struct mutex *blocked_on = __get_task_blocked_on(task); - DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list)); DEBUG_LOCKS_WARN_ON(waiter->task != task); DEBUG_LOCKS_WARN_ON(blocked_on && blocked_on != lock); @@ -74,7 +72,6 @@ void debug_mutex_unlock(struct mutex *lock) { if (likely(debug_locks)) { DEBUG_LOCKS_WARN_ON(lock->magic != lock); - DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next); } } diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index c867f6c15530..95f1822122a1 100644 --- a/kernel/locking/mutex.c +++ b/kernel/locking/mutex.c @@ -47,7 +47,7 @@ static void __mutex_init_generic(struct mutex *lock) { atomic_long_set(&lock->owner, 0); raw_spin_lock_init(&lock->wait_lock); - INIT_LIST_HEAD(&lock->wait_list); + lock->first_waiter = NULL; #ifdef CONFIG_MUTEX_SPIN_ON_OWNER osq_lock_init(&lock->osq); #endif @@ -194,33 +194,42 @@ static inline void __mutex_clear_flag(struct mutex *lock, unsigned long flag) atomic_long_andnot(flag, &lock->owner); } -static inline bool __mutex_waiter_is_first(struct mutex *lock, struct mutex_waiter *waiter) -{ - return list_first_entry(&lock->wait_list, struct mutex_waiter, list) == waiter; -} - /* * Add @waiter to a given location in the lock wait_list and set the * FLAG_WAITERS flag if it's the first waiter. */ static void __mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter, - struct list_head *list) + struct mutex_waiter *first) { hung_task_set_blocker(lock, BLOCKER_TYPE_MUTEX); debug_mutex_add_waiter(lock, waiter, current); - list_add_tail(&waiter->list, list); - if (__mutex_waiter_is_first(lock, waiter)) + if (!first) + first = lock->first_waiter; + + if (first) { + list_add_tail(&waiter->list, &first->list); + } else { + INIT_LIST_HEAD(&waiter->list); + lock->first_waiter = waiter; __mutex_set_flag(lock, MUTEX_FLAG_WAITERS); + } } static void __mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter) { - list_del(&waiter->list); - if (likely(list_empty(&lock->wait_list))) + if (list_empty(&waiter->list)) { __mutex_clear_flag(lock, MUTEX_FLAGS); + lock->first_waiter = NULL; + } else { + if (lock->first_waiter == waiter) { + lock->first_waiter = list_first_entry(&waiter->list, + struct mutex_waiter, list); + } + list_del(&waiter->list); + } debug_mutex_remove_waiter(lock, waiter, current); hung_task_clear_blocker(); @@ -340,7 +349,7 @@ bool ww_mutex_spin_on_owner(struct mutex *lock, struct ww_acquire_ctx *ww_ctx, * Similarly, stop spinning if we are no longer the * first waiter. */ - if (waiter && !__mutex_waiter_is_first(lock, waiter)) + if (waiter && lock->first_waiter != waiter) return false; return true; @@ -645,7 +654,7 @@ __mutex_lock_common(struct mutex *lock, unsigned int state, unsigned int subclas if (!use_ww_ctx) { /* add waiting tasks to the end of the waitqueue (FIFO): */ - __mutex_add_waiter(lock, &waiter, &lock->wait_list); + __mutex_add_waiter(lock, &waiter, NULL); } else { /* * Add in stamp order, waking up waiters that must kill @@ -691,7 +700,7 @@ __mutex_lock_common(struct mutex *lock, unsigned int state, unsigned int subclas schedule_preempt_disabled(); - first = __mutex_waiter_is_first(lock, &waiter); + first = lock->first_waiter == &waiter; /* * As we likely have been woken up by task @@ -734,8 +743,7 @@ acquired: * Wound-Wait; we stole the lock (!first_waiter), check the * waiters as anyone might want to wound us. */ - if (!ww_ctx->is_wait_die && - !__mutex_waiter_is_first(lock, &waiter)) + if (!ww_ctx->is_wait_die && lock->first_waiter != &waiter) __ww_mutex_check_waiters(lock, ww_ctx, &wake_q); } @@ -931,6 +939,7 @@ EXPORT_SYMBOL_GPL(ww_mutex_lock_interruptible); static noinline void __sched __mutex_unlock_slowpath(struct mutex *lock, unsigned long ip) { struct task_struct *next = NULL; + struct mutex_waiter *waiter; DEFINE_WAKE_Q(wake_q); unsigned long owner; unsigned long flags; @@ -962,12 +971,8 @@ static noinline void __sched __mutex_unlock_slowpath(struct mutex *lock, unsigne raw_spin_lock_irqsave(&lock->wait_lock, flags); debug_mutex_unlock(lock); - if (!list_empty(&lock->wait_list)) { - /* get the first entry from the wait-list: */ - struct mutex_waiter *waiter = - list_first_entry(&lock->wait_list, - struct mutex_waiter, list); - + waiter = lock->first_waiter; + if (waiter) { next = waiter->task; debug_mutex_wake_waiter(lock, waiter); diff --git a/kernel/locking/ww_mutex.h b/kernel/locking/ww_mutex.h index 31a785afee6c..a0847e91ae04 100644 --- a/kernel/locking/ww_mutex.h +++ b/kernel/locking/ww_mutex.h @@ -8,20 +8,14 @@ static inline struct mutex_waiter * __ww_waiter_first(struct mutex *lock) { - struct mutex_waiter *w; - - w = list_first_entry(&lock->wait_list, struct mutex_waiter, list); - if (list_entry_is_head(w, &lock->wait_list, list)) - return NULL; - - return w; + return lock->first_waiter; } static inline struct mutex_waiter * __ww_waiter_next(struct mutex *lock, struct mutex_waiter *w) { w = list_next_entry(w, list); - if (list_entry_is_head(w, &lock->wait_list, list)) + if (lock->first_waiter == w) return NULL; return w; @@ -31,7 +25,7 @@ static inline struct mutex_waiter * __ww_waiter_prev(struct mutex *lock, struct mutex_waiter *w) { w = list_prev_entry(w, list); - if (list_entry_is_head(w, &lock->wait_list, list)) + if (lock->first_waiter == w) return NULL; return w; @@ -40,22 +34,17 @@ __ww_waiter_prev(struct mutex *lock, struct mutex_waiter *w) static inline struct mutex_waiter * __ww_waiter_last(struct mutex *lock) { - struct mutex_waiter *w; - - w = list_last_entry(&lock->wait_list, struct mutex_waiter, list); - if (list_entry_is_head(w, &lock->wait_list, list)) - return NULL; + struct mutex_waiter *w = lock->first_waiter; + if (w) + w = list_prev_entry(w, list); return w; } static inline void __ww_waiter_add(struct mutex *lock, struct mutex_waiter *waiter, struct mutex_waiter *pos) { - struct list_head *p = &lock->wait_list; - if (pos) - p = &pos->list; - __mutex_add_waiter(lock, waiter, p); + __mutex_add_waiter(lock, waiter, pos); } static inline struct task_struct * |