diff options
Diffstat (limited to 'kernel/locking/rwsem-xadd.c')
| -rw-r--r-- | kernel/locking/rwsem-xadd.c | 40 |
1 files changed, 25 insertions, 15 deletions
diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c index 2337b4bb2366..2ad8d8dc3bb1 100644 --- a/kernel/locking/rwsem-xadd.c +++ b/kernel/locking/rwsem-xadd.c @@ -224,10 +224,9 @@ struct rw_semaphore __sched *rwsem_down_read_failed(struct rw_semaphore *sem) { long count, adjustment = -RWSEM_ACTIVE_READ_BIAS; struct rwsem_waiter waiter; - struct task_struct *tsk = current; - WAKE_Q(wake_q); + DEFINE_WAKE_Q(wake_q); - waiter.task = tsk; + waiter.task = current; waiter.type = RWSEM_WAITING_FOR_READ; raw_spin_lock_irq(&sem->wait_lock); @@ -254,13 +253,13 @@ struct rw_semaphore __sched *rwsem_down_read_failed(struct rw_semaphore *sem) /* wait to be given the lock */ while (true) { - set_task_state(tsk, TASK_UNINTERRUPTIBLE); + set_current_state(TASK_UNINTERRUPTIBLE); if (!waiter.task) break; schedule(); } - __set_task_state(tsk, TASK_RUNNING); + __set_current_state(TASK_RUNNING); return sem; } EXPORT_SYMBOL(rwsem_down_read_failed); @@ -336,7 +335,11 @@ static inline bool rwsem_can_spin_on_owner(struct rw_semaphore *sem) goto done; } - ret = owner->on_cpu; + /* + * As lock holder preemption issue, we both skip spinning if task is not + * on cpu or its cpu is preempted + */ + ret = owner->on_cpu && !vcpu_is_preempted(task_cpu(owner)); done: rcu_read_unlock(); return ret; @@ -362,13 +365,17 @@ static noinline bool rwsem_spin_on_owner(struct rw_semaphore *sem) */ barrier(); - /* abort spinning when need_resched or owner is not running */ - if (!owner->on_cpu || need_resched()) { + /* + * abort spinning when need_resched or owner is not running or + * owner's cpu is preempted. + */ + if (!owner->on_cpu || need_resched() || + vcpu_is_preempted(task_cpu(owner))) { rcu_read_unlock(); return false; } - cpu_relax_lowlatency(); + cpu_relax(); } rcu_read_unlock(); out: @@ -423,7 +430,7 @@ static bool rwsem_optimistic_spin(struct rw_semaphore *sem) * memory barriers as we'll eventually observe the right * values at the cost of a few extra spins. */ - cpu_relax_lowlatency(); + cpu_relax(); } osq_unlock(&sem->osq); done: @@ -461,7 +468,7 @@ __rwsem_down_write_failed_common(struct rw_semaphore *sem, int state) bool waiting = true; /* any queued threads before us */ struct rwsem_waiter waiter; struct rw_semaphore *ret = sem; - WAKE_Q(wake_q); + DEFINE_WAKE_Q(wake_q); /* undo write bias from down_write operation, stop active locking */ count = atomic_long_sub_return(RWSEM_ACTIVE_WRITE_BIAS, &sem->count); @@ -495,8 +502,6 @@ __rwsem_down_write_failed_common(struct rw_semaphore *sem, int state) * wake any read locks that were queued ahead of us. */ if (count > RWSEM_WAITING_BIAS) { - WAKE_Q(wake_q); - __rwsem_mark_wake(sem, RWSEM_WAKE_READERS, &wake_q); /* * The wakeup is normally called _after_ the wait_lock @@ -506,6 +511,11 @@ __rwsem_down_write_failed_common(struct rw_semaphore *sem, int state) * for attempting rwsem_try_write_lock(). */ wake_up_q(&wake_q); + + /* + * Reinitialize wake_q after use. + */ + wake_q_init(&wake_q); } } else @@ -571,7 +581,7 @@ __visible struct rw_semaphore *rwsem_wake(struct rw_semaphore *sem) { unsigned long flags; - WAKE_Q(wake_q); + DEFINE_WAKE_Q(wake_q); /* * If a spinner is present, it is not necessary to do the wakeup. @@ -625,7 +635,7 @@ __visible struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem) { unsigned long flags; - WAKE_Q(wake_q); + DEFINE_WAKE_Q(wake_q); raw_spin_lock_irqsave(&sem->wait_lock, flags); |