Add trace_contended_release() calls to the slowpath unlock paths of sleepable locks: mutex, rtmutex, semaphore, rwsem, percpu-rwsem, and RT-specific rwbase locks. Each call site fires only when there are blocked waiters being woken, except percpu_up_write() which always wakes via __wake_up().
Signed-off-by: Dmitry Ilvokhin <[email protected]> --- kernel/locking/mutex.c | 1 + kernel/locking/percpu-rwsem.c | 3 +++ kernel/locking/rtmutex.c | 1 + kernel/locking/rwbase_rt.c | 8 +++++++- kernel/locking/rwsem.c | 9 +++++++-- kernel/locking/semaphore.c | 4 +++- 6 files changed, 22 insertions(+), 4 deletions(-) diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index c867f6c15530..54ca045987a2 100644 --- a/kernel/locking/mutex.c +++ b/kernel/locking/mutex.c @@ -970,6 +970,7 @@ static noinline void __sched __mutex_unlock_slowpath(struct mutex *lock, unsigne next = waiter->task; + trace_contended_release(lock); debug_mutex_wake_waiter(lock, waiter); __clear_task_blocked_on(next, lock); wake_q_add(&wake_q, next); diff --git a/kernel/locking/percpu-rwsem.c b/kernel/locking/percpu-rwsem.c index 4190635458da..0f2e8e63d252 100644 --- a/kernel/locking/percpu-rwsem.c +++ b/kernel/locking/percpu-rwsem.c @@ -263,6 +263,8 @@ void percpu_up_write(struct percpu_rw_semaphore *sem) { rwsem_release(&sem->dep_map, _RET_IP_); + trace_contended_release(sem); + /* * Signal the writer is done, no fast path yet. * @@ -297,6 +299,7 @@ void __percpu_up_read_slowpath(struct percpu_rw_semaphore *sem) * writer. */ smp_mb(); /* B matches C */ + trace_contended_release(sem); /* * In other words, if they see our decrement (presumably to * aggregate zero, as that is the only time it matters) they diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index c80902eacd79..e0873f0ed982 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -1457,6 +1457,7 @@ static void __sched rt_mutex_slowunlock(struct rt_mutex_base *lock) raw_spin_lock_irqsave(&lock->wait_lock, flags); } + trace_contended_release(lock); /* * The wakeup next waiter path does not suffer from the above * race. See the comments there. diff --git a/kernel/locking/rwbase_rt.c b/kernel/locking/rwbase_rt.c index 9f4322c07486..42f3658c0059 100644 --- a/kernel/locking/rwbase_rt.c +++ b/kernel/locking/rwbase_rt.c @@ -162,8 +162,10 @@ static void __sched __rwbase_read_unlock(struct rwbase_rt *rwb, * worst case which can happen is a spurious wakeup. */ owner = rt_mutex_owner(rtm); - if (owner) + if (owner) { + trace_contended_release(rwb); rt_mutex_wake_q_add_task(&wqh, owner, state); + } /* Pairs with the preempt_enable in rt_mutex_wake_up_q() */ preempt_disable(); @@ -204,6 +206,8 @@ static inline void rwbase_write_unlock(struct rwbase_rt *rwb) unsigned long flags; raw_spin_lock_irqsave(&rtm->wait_lock, flags); + if (rt_mutex_has_waiters(rtm)) + trace_contended_release(rwb); __rwbase_write_unlock(rwb, WRITER_BIAS, flags); } @@ -213,6 +217,8 @@ static inline void rwbase_write_downgrade(struct rwbase_rt *rwb) unsigned long flags; raw_spin_lock_irqsave(&rtm->wait_lock, flags); + if (rt_mutex_has_waiters(rtm)) + trace_contended_release(rwb); /* Release it and account current as reader */ __rwbase_write_unlock(rwb, WRITER_BIAS - 1, flags); } diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c index 24df4d98f7d2..4e61dc0bb045 100644 --- a/kernel/locking/rwsem.c +++ b/kernel/locking/rwsem.c @@ -1360,6 +1360,7 @@ static inline void __up_read(struct rw_semaphore *sem) if (unlikely((tmp & (RWSEM_LOCK_MASK|RWSEM_FLAG_WAITERS)) == RWSEM_FLAG_WAITERS)) { clear_nonspinnable(sem); + trace_contended_release(sem); rwsem_wake(sem); } preempt_enable(); @@ -1383,8 +1384,10 @@ static inline void __up_write(struct rw_semaphore *sem) preempt_disable(); rwsem_clear_owner(sem); tmp = atomic_long_fetch_add_release(-RWSEM_WRITER_LOCKED, &sem->count); - if (unlikely(tmp & RWSEM_FLAG_WAITERS)) + if (unlikely(tmp & RWSEM_FLAG_WAITERS)) { + trace_contended_release(sem); rwsem_wake(sem); + } preempt_enable(); } @@ -1407,8 +1410,10 @@ static inline void __downgrade_write(struct rw_semaphore *sem) tmp = atomic_long_fetch_add_release( -RWSEM_WRITER_LOCKED+RWSEM_READER_BIAS, &sem->count); rwsem_set_reader_owned(sem); - if (tmp & RWSEM_FLAG_WAITERS) + if (tmp & RWSEM_FLAG_WAITERS) { + trace_contended_release(sem); rwsem_downgrade_wake(sem); + } preempt_enable(); } diff --git a/kernel/locking/semaphore.c b/kernel/locking/semaphore.c index 3ef032e22f7e..3cef5ba88f7e 100644 --- a/kernel/locking/semaphore.c +++ b/kernel/locking/semaphore.c @@ -231,8 +231,10 @@ void __sched up(struct semaphore *sem) else __up(sem, &wake_q); raw_spin_unlock_irqrestore(&sem->lock, flags); - if (!wake_q_empty(&wake_q)) + if (!wake_q_empty(&wake_q)) { + trace_contended_release(sem); wake_up_q(&wake_q); + } } EXPORT_SYMBOL(up); -- 2.47.3
