diff options
Diffstat (limited to 'kernel/locking')
| -rw-r--r-- | kernel/locking/lockdep.c | 2 | ||||
| -rw-r--r-- | kernel/locking/locktorture.c | 4 | ||||
| -rw-r--r-- | kernel/locking/mutex.c | 11 | ||||
| -rw-r--r-- | kernel/locking/rtmutex.c | 10 | ||||
| -rw-r--r-- | kernel/locking/rtmutex_api.c | 30 | ||||
| -rw-r--r-- | kernel/locking/rwsem.c | 191 | ||||
| -rw-r--r-- | kernel/locking/spinlock_rt.c | 6 | ||||
| -rw-r--r-- | kernel/locking/ww_rt_mutex.c | 2 |
8 files changed, 128 insertions, 128 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 2270ec68f10a..4a882f83aeb9 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -5485,6 +5485,7 @@ static noinstr void check_flags(unsigned long flags) } } +#ifndef CONFIG_PREEMPT_RT /* * We dont accurately track softirq state in e.g. * hardirq contexts (such as on 4KSTACKS), so only @@ -5499,6 +5500,7 @@ static noinstr void check_flags(unsigned long flags) DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled); } } +#endif if (!debug_locks) print_irqtrace_events(current); diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c index 397ac13d2ef7..9c2fb613a55d 100644 --- a/kernel/locking/locktorture.c +++ b/kernel/locking/locktorture.c @@ -1047,7 +1047,7 @@ static int __init lock_torture_init(void) sizeof(writer_tasks[0]), GFP_KERNEL); if (writer_tasks == NULL) { - VERBOSE_TOROUT_ERRSTRING("writer_tasks: Out of memory"); + TOROUT_ERRSTRING("writer_tasks: Out of memory"); firsterr = -ENOMEM; goto unwind; } @@ -1058,7 +1058,7 @@ static int __init lock_torture_init(void) sizeof(reader_tasks[0]), GFP_KERNEL); if (reader_tasks == NULL) { - VERBOSE_TOROUT_ERRSTRING("reader_tasks: Out of memory"); + TOROUT_ERRSTRING("reader_tasks: Out of memory"); kfree(writer_tasks); writer_tasks = NULL; firsterr = -ENOMEM; diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index db1913611192..5e3585950ec8 100644 --- a/kernel/locking/mutex.c +++ b/kernel/locking/mutex.c @@ -367,8 +367,7 @@ bool mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner, /* * Use vcpu_is_preempted to detect lock holder preemption issue. */ - if (!owner->on_cpu || need_resched() || - vcpu_is_preempted(task_cpu(owner))) { + if (!owner_on_cpu(owner) || need_resched()) { ret = false; break; } @@ -403,14 +402,8 @@ static inline int mutex_can_spin_on_owner(struct mutex *lock) * structure won't go away during the spinning period. */ owner = __mutex_owner(lock); - - /* - * As lock holder preemption issue, we both skip spinning if task is not - * on cpu or its cpu is preempted - */ - if (owner) - retval = owner->on_cpu && !vcpu_is_preempted(task_cpu(owner)); + retval = owner_on_cpu(owner); /* * If lock->owner is not set, the mutex has been released. Return true diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index 0c6a48dfcecb..8555c4efe97c 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -1103,8 +1103,11 @@ static int __sched task_blocks_on_rt_mutex(struct rt_mutex_base *lock, * the other will detect the deadlock and return -EDEADLOCK, * which is wrong, as the other waiter is not in a deadlock * situation. + * + * Except for ww_mutex, in that case the chain walk must already deal + * with spurious cycles, see the comments at [3] and [6]. */ - if (owner == task) + if (owner == task && !(build_ww_mutex() && ww_ctx)) return -EDEADLK; raw_spin_lock(&task->pi_lock); @@ -1379,9 +1382,8 @@ static bool rtmutex_spin_on_owner(struct rt_mutex_base *lock, * for CONFIG_PREEMPT_RCU=y) * - the VCPU on which owner runs is preempted */ - if (!owner->on_cpu || need_resched() || - rt_mutex_waiter_is_top_waiter(lock, waiter) || - vcpu_is_preempted(task_cpu(owner))) { + if (!owner_on_cpu(owner) || need_resched() || + !rt_mutex_waiter_is_top_waiter(lock, waiter)) { res = false; break; } diff --git a/kernel/locking/rtmutex_api.c b/kernel/locking/rtmutex_api.c index 5c9299aaabae..900220941caa 100644 --- a/kernel/locking/rtmutex_api.c +++ b/kernel/locking/rtmutex_api.c @@ -21,12 +21,13 @@ int max_lock_depth = 1024; */ static __always_inline int __rt_mutex_lock_common(struct rt_mutex *lock, unsigned int state, + struct lockdep_map *nest_lock, unsigned int subclass) { int ret; might_sleep(); - mutex_acquire(&lock->dep_map, subclass, 0, _RET_IP_); + mutex_acquire_nest(&lock->dep_map, subclass, 0, nest_lock, _RET_IP_); ret = __rt_mutex_lock(&lock->rtmutex, state); if (ret) mutex_release(&lock->dep_map, _RET_IP_); @@ -48,10 +49,16 @@ EXPORT_SYMBOL(rt_mutex_base_init); */ void __sched rt_mutex_lock_nested(struct rt_mutex *lock, unsigned int subclass) { - __rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, subclass); + __rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, NULL, subclass); } EXPORT_SYMBOL_GPL(rt_mutex_lock_nested); +void __sched _rt_mutex_lock_nest_lock(struct rt_mutex *lock, struct lockdep_map *nest_lock) +{ + __rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, nest_lock, 0); +} +EXPORT_SYMBOL_GPL(_rt_mutex_lock_nest_lock); + #else /* !CONFIG_DEBUG_LOCK_ALLOC */ /** @@ -61,7 +68,7 @@ EXPORT_SYMBOL_GPL(rt_mutex_lock_nested); */ void __sched rt_mutex_lock(struct rt_mutex *lock) { - __rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0); + __rt_mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, NULL, 0); } EXPORT_SYMBOL_GPL(rt_mutex_lock); #endif @@ -77,11 +84,26 @@ EXPORT_SYMBOL_GPL(rt_mutex_lock); */ int __sched rt_mutex_lock_interruptible(struct rt_mutex *lock) { - return __rt_mutex_lock_common(lock, TASK_INTERRUPTIBLE, 0); + return __rt_mutex_lock_common(lock, TASK_INTERRUPTIBLE, NULL, 0); } EXPORT_SYMBOL_GPL(rt_mutex_lock_interruptible); /** + * rt_mutex_lock_killable - lock a rt_mutex killable + * + * @lock: the rt_mutex to be locked + * + * Returns: + * 0 on success + * -EINTR when interrupted by a signal + */ +int __sched rt_mutex_lock_killable(struct rt_mutex *lock) +{ + return __rt_mutex_lock_common(lock, TASK_KILLABLE, NULL, 0); +} +EXPORT_SYMBOL_GPL(rt_mutex_lock_killable); + +/** * rt_mutex_trylock - try to lock a rt_mutex * * @lock: the rt_mutex to be locked diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c index c51387a43265..69aba4abe104 100644 --- a/kernel/locking/rwsem.c +++ b/kernel/locking/rwsem.c @@ -105,9 +105,9 @@ * atomic_long_cmpxchg() will be used to obtain writer lock. * * There are three places where the lock handoff bit may be set or cleared. - * 1) rwsem_mark_wake() for readers. - * 2) rwsem_try_write_lock() for writers. - * 3) Error path of rwsem_down_write_slowpath(). + * 1) rwsem_mark_wake() for readers -- set, clear + * 2) rwsem_try_write_lock() for writers -- set, clear + * 3) rwsem_del_waiter() -- clear * * For all the above cases, wait_lock will be held. A writer must also * be the first one in the wait_list to be eligible for setting the handoff @@ -334,6 +334,9 @@ struct rwsem_waiter { struct task_struct *task; enum rwsem_waiter_type type; unsigned long timeout; + + /* Writer only, not initialized in reader */ + bool handoff_set; }; #define rwsem_first_waiter(sem) \ list_first_entry(&sem->wait_list, struct rwsem_waiter, list) @@ -344,12 +347,6 @@ enum rwsem_wake_type { RWSEM_WAKE_READ_OWNED /* Waker thread holds the read lock */ }; -enum writer_wait_state { - WRITER_NOT_FIRST, /* Writer is not first in wait list */ - WRITER_FIRST, /* Writer is first in wait list */ - WRITER_HANDOFF /* Writer is first & handoff needed */ -}; - /* * The typical HZ value is either 250 or 1000. So set the minimum waiting * time to at least 4ms or 1 jiffy (if it is higher than 4ms) in the wait @@ -365,6 +362,31 @@ enum writer_wait_state { */ #define MAX_READERS_WAKEUP 0x100 +static inline void +rwsem_add_waiter(struct rw_semaphore *sem, struct rwsem_waiter *waiter) +{ + lockdep_assert_held(&sem->wait_lock); + list_add_tail(&waiter->list, &sem->wait_list); + /* caller will set RWSEM_FLAG_WAITERS */ +} + +/* + * Remove a waiter from the wait_list and clear flags. + * + * Both rwsem_mark_wake() and rwsem_try_write_lock() contain a full 'copy' of + * this function. Modify with care. + */ +static inline void +rwsem_del_waiter(struct rw_semaphore *sem, struct rwsem_waiter *waiter) +{ + lockdep_assert_held(&sem->wait_lock); + list_del(&waiter->list); + if (likely(!list_empty(&sem->wait_list))) + return; + + atomic_long_andnot(RWSEM_FLAG_HANDOFF | RWSEM_FLAG_WAITERS, &sem->count); +} + /* * handle the lock release when processes blocked on it that can now run * - if we come here from up_xxxx(), then the RWSEM_FLAG_WAITERS bit must @@ -376,6 +398,8 @@ enum writer_wait_state { * preferably when the wait_lock is released * - woken process blocks are discarded from the list after having task zeroed * - writers are only marked woken if downgrading is false + * + * Implies rwsem_del_waiter() for all woken readers. */ static void rwsem_mark_wake(struct rw_semaphore *sem, enum rwsem_wake_type wake_type, @@ -490,18 +514,25 @@ static void rwsem_mark_wake(struct rw_semaphore *sem, adjustment = woken * RWSEM_READER_BIAS - adjustment; lockevent_cond_inc(rwsem_wake_reader, woken); + + oldcount = atomic_long_read(&sem->count); if (list_empty(&sem->wait_list)) { - /* hit end of list above */ + /* + * Combined with list_move_tail() above, this implies + * rwsem_del_waiter(). + */ adjustment -= RWSEM_FLAG_WAITERS; + if (oldcount & RWSEM_FLAG_HANDOFF) + adjustment -= RWSEM_FLAG_HANDOFF; + } else if (woken) { + /* + * When we've woken a reader, we no longer need to force + * writers to give up the lock and we can clear HANDOFF. + */ + if (oldcount & RWSEM_FLAG_HANDOFF) + adjustment -= RWSEM_FLAG_HANDOFF; } - /* - * When we've woken a reader, we no longer need to force writers - * to give up the lock and we can clear HANDOFF. - */ - if (woken && (atomic_long_read(&sem->count) & RWSEM_FLAG_HANDOFF)) - adjustment -= RWSEM_FLAG_HANDOFF; - if (adjustment) atomic_long_add(adjustment, &sem->count); @@ -532,12 +563,12 @@ static void rwsem_mark_wake(struct rw_semaphore *sem, * race conditions between checking the rwsem wait list and setting the * sem->count accordingly. * - * If wstate is WRITER_HANDOFF, it will make sure that either the handoff - * bit is set or the lock is acquired with handoff bit cleared. + * Implies rwsem_del_waiter() on success. */ static inline bool rwsem_try_write_lock(struct rw_semaphore *sem, - enum writer_wait_state wstate) + struct rwsem_waiter *waiter) { + bool first = rwsem_first_waiter(sem) == waiter; long count, new; lockdep_assert_held(&sem->wait_lock); @@ -546,13 +577,19 @@ static inline bool rwsem_try_write_lock(struct rw_semaphore *sem, do { bool has_handoff = !!(count & RWSEM_FLAG_HANDOFF); - if (has_handoff && wstate == WRITER_NOT_FIRST) - return false; + if (has_handoff) { + if (!first) + return false; + + /* First waiter inherits a previously set handoff bit */ + waiter->handoff_set = true; + } new = count; if (count & RWSEM_LOCK_MASK) { - if (has_handoff || (wstate != WRITER_HANDOFF)) + if (has_handoff || (!rt_task(waiter->task) && + !time_after(jiffies, waiter->timeout))) return false; new |= RWSEM_FLAG_HANDOFF; @@ -569,9 +606,17 @@ static inline bool rwsem_try_write_lock(struct rw_semaphore *sem, * We have either acquired the lock with handoff bit cleared or * set the handoff bit. */ - if (new & RWSEM_FLAG_HANDOFF) + if (new & RWSEM_FLAG_HANDOFF) { + waiter->handoff_set = true; + lockevent_inc(rwsem_wlock_handoff); return false; + } + /* + * Have rwsem_try_write_lock() fully imply rwsem_del_waiter() on + * success. + */ + list_del(&waiter->list); rwsem_set_owner(sem); return true; } @@ -613,15 +658,6 @@ static inline bool rwsem_try_write_lock_unqueued(struct rw_semaphore *sem) return false; } -static inline bool owner_on_cpu(struct task_struct *owner) -{ - /* - * As lock holder preemption issue, we both skip spinning if - * task is not on cpu or its cpu is preempted - */ - return owner->on_cpu && !vcpu_is_preempted(task_cpu(owner)); -} - static inline bool rwsem_can_spin_on_owner(struct rw_semaphore *sem) { struct task_struct *owner; @@ -956,7 +992,7 @@ queue: } adjustment += RWSEM_FLAG_WAITERS; } - list_add_tail(&waiter.list, &sem->wait_list); + rwsem_add_waiter(sem, &waiter); /* we're now waiting on the lock, but no longer actively locking */ count = atomic_long_add_return(adjustment, &sem->count); @@ -1002,11 +1038,7 @@ queue: return sem; out_nolock: - list_del(&waiter.list); - if (list_empty(&sem->wait_list)) { - atomic_long_andnot(RWSEM_FLAG_WAITERS|RWSEM_FLAG_HANDOFF, - &sem->count); - } + rwsem_del_waiter(sem, &waiter); raw_spin_unlock_irq(&sem->wait_lock); __set_current_state(TASK_RUNNING); lockevent_inc(rwsem_rlock_fail); @@ -1020,9 +1052,7 @@ static struct rw_semaphore * rwsem_down_write_slowpath(struct rw_semaphore *sem, int state) { long count; - enum writer_wait_state wstate; struct rwsem_waiter waiter; - struct rw_semaphore *ret = sem; DEFINE_WAKE_Q(wake_q); /* do optimistic spinning and steal lock if possible */ @@ -1038,16 +1068,13 @@ rwsem_down_write_slowpath(struct rw_semaphore *sem, int state) waiter.task = current; waiter.type = RWSEM_WAITING_FOR_WRITE; waiter.timeout = jiffies + RWSEM_WAIT_TIMEOUT; + waiter.handoff_set = false; raw_spin_lock_irq(&sem->wait_lock); - - /* account for this before adding a new element to the list */ - wstate = list_empty(&sem->wait_list) ? WRITER_FIRST : WRITER_NOT_FIRST; - - list_add_tail(&waiter.list, &sem->wait_list); + rwsem_add_waiter(sem, &waiter); /* we're now waiting on the lock */ - if (wstate == WRITER_NOT_FIRST) { + if (rwsem_first_waiter(sem) != &waiter) { count = atomic_long_read(&sem->count); /* @@ -1083,13 +1110,16 @@ wait: /* wait until we successfully acquire the lock */ set_current_state(state); for (;;) { - if (rwsem_try_write_lock(sem, wstate)) { + if (rwsem_try_write_lock(sem, &waiter)) { /* rwsem_try_write_lock() implies ACQUIRE on success */ break; } raw_spin_unlock_irq(&sem->wait_lock); + if (signal_pending_state(state, current)) + goto out_nolock; + /* * After setting the handoff bit and failing to acquire * the lock, attempt to spin on owner to accelerate lock @@ -1098,7 +1128,7 @@ wait: * In this case, we attempt to acquire the lock again * without sleeping. */ - if (wstate == WRITER_HANDOFF) { + if (waiter.handoff_set) { enum owner_state owner_state; preempt_disable(); @@ -1109,66 +1139,26 @@ wait: goto trylock_again; } - /* Block until there are no active lockers. */ - for (;;) { - if (signal_pending_state(state, current)) - goto out_nolock; - - schedule(); - lockevent_inc(rwsem_sleep_writer); - set_current_state(state); - /* - * If HANDOFF bit is set, unconditionally do - * a trylock. - */ - if (wstate == WRITER_HANDOFF) - break; - - if ((wstate == WRITER_NOT_FIRST) && - (rwsem_first_waiter(sem) == &waiter)) - wstate = WRITER_FIRST; - - count = atomic_long_read(&sem->count); - if (!(count & RWSEM_LOCK_MASK)) - break; - - /* - * The setting of the handoff bit is deferred - * until rwsem_try_write_lock() is called. - */ - if ((wstate == WRITER_FIRST) && (rt_task(current) || - time_after(jiffies, waiter.timeout))) { - wstate = WRITER_HANDOFF; - lockevent_inc(rwsem_wlock_handoff); - break; - } - } + schedule(); + lockevent_inc(rwsem_sleep_writer); + set_current_state(state); trylock_again: raw_spin_lock_irq(&sem->wait_lock); } __set_current_state(TASK_RUNNING); - list_del(&waiter.list); raw_spin_unlock_irq(&sem->wait_lock); lockevent_inc(rwsem_wlock); - - return ret; + return sem; out_nolock: __set_current_state(TASK_RUNNING); raw_spin_lock_irq(&sem->wait_lock); - list_del(&waiter.list); - - if (unlikely(wstate == WRITER_HANDOFF)) - atomic_long_add(-RWSEM_FLAG_HANDOFF, &sem->count); - - if (list_empty(&sem->wait_list)) - atomic_long_andnot(RWSEM_FLAG_WAITERS, &sem->count); - else + rwsem_del_waiter(sem, &waiter); + if (!list_empty(&sem->wait_list)) rwsem_mark_wake(sem, RWSEM_WAKE_ANY, &wake_q); raw_spin_unlock_irq(&sem->wait_lock); wake_up_q(&wake_q); lockevent_inc(rwsem_wlock_fail); - return ERR_PTR(-EINTR); } @@ -1249,17 +1239,14 @@ static inline int __down_read_trylock(struct rw_semaphore *sem) DEBUG_RWSEMS_WARN_ON(sem->magic != sem, sem); - /* - * Optimize for the case when the rwsem is not locked at all. - */ - tmp = RWSEM_UNLOCKED_VALUE; - do { + tmp = atomic_long_read(&sem->count); + while (!(tmp & RWSEM_READ_FAILED_MASK)) { if (atomic_long_try_cmpxchg_acquire(&sem->count, &tmp, - tmp + RWSEM_READER_BIAS)) { + tmp + RWSEM_READER_BIAS)) { rwsem_set_reader_owned(sem); return 1; } - } while (!(tmp & RWSEM_READ_FAILED_MASK)); + } return 0; } diff --git a/kernel/locking/spinlock_rt.c b/kernel/locking/spinlock_rt.c index b2e553f9255b..9e396a09fe0f 100644 --- a/kernel/locking/spinlock_rt.c +++ b/kernel/locking/spinlock_rt.c @@ -257,12 +257,6 @@ void __sched rt_write_unlock(rwlock_t *rwlock) } EXPORT_SYMBOL(rt_write_unlock); -int __sched rt_rwlock_is_contended(rwlock_t *rwlock) -{ - return rw_base_is_contended(&rwlock->rwbase); -} -EXPORT_SYMBOL(rt_rwlock_is_contended); - #ifdef CONFIG_DEBUG_LOCK_ALLOC void __rt_rwlock_init(rwlock_t *rwlock, const char *name, struct lock_class_key *key) diff --git a/kernel/locking/ww_rt_mutex.c b/kernel/locking/ww_rt_mutex.c index 0e00205cf467..d1473c624105 100644 --- a/kernel/locking/ww_rt_mutex.c +++ b/kernel/locking/ww_rt_mutex.c @@ -26,7 +26,7 @@ int ww_mutex_trylock(struct ww_mutex *lock, struct ww_acquire_ctx *ww_ctx) if (__rt_mutex_trylock(&rtm->rtmutex)) { ww_mutex_set_context_fastpath(lock, ww_ctx); - mutex_acquire_nest(&rtm->dep_map, 0, 1, ww_ctx->dep_map, _RET_IP_); + mutex_acquire_nest(&rtm->dep_map, 0, 1, &ww_ctx->dep_map, _RET_IP_); return 1; } |