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Diffstat (limited to 'kernel/sched/completion.c')
-rw-r--r--kernel/sched/completion.c30
1 files changed, 23 insertions, 7 deletions
diff --git a/kernel/sched/completion.c b/kernel/sched/completion.c
index 13fc5ae9bf2f..cc873075c3bd 100644
--- a/kernel/sched/completion.c
+++ b/kernel/sched/completion.c
@@ -32,6 +32,12 @@ void complete(struct completion *x)
unsigned long flags;
spin_lock_irqsave(&x->wait.lock, flags);
+
+ /*
+ * Perform commit of crossrelease here.
+ */
+ complete_release_commit(x);
+
if (x->done != UINT_MAX)
x->done++;
__wake_up_locked(&x->wait, TASK_NORMAL, 1);
@@ -47,6 +53,13 @@ EXPORT_SYMBOL(complete);
*
* It may be assumed that this function implies a write memory barrier before
* changing the task state if and only if any tasks are woken up.
+ *
+ * Since complete_all() sets the completion of @x permanently to done
+ * to allow multiple waiters to finish, a call to reinit_completion()
+ * must be used on @x if @x is to be used again. The code must make
+ * sure that all waiters have woken and finished before reinitializing
+ * @x. Also note that the function completion_done() can not be used
+ * to know if there are still waiters after complete_all() has been called.
*/
void complete_all(struct completion *x)
{
@@ -92,9 +105,14 @@ __wait_for_common(struct completion *x,
{
might_sleep();
+ complete_acquire(x);
+
spin_lock_irq(&x->wait.lock);
timeout = do_wait_for_common(x, action, timeout, state);
spin_unlock_irq(&x->wait.lock);
+
+ complete_release(x);
+
return timeout;
}
@@ -297,9 +315,12 @@ EXPORT_SYMBOL(try_wait_for_completion);
* Return: 0 if there are waiters (wait_for_completion() in progress)
* 1 if there are no waiters.
*
+ * Note, this will always return true if complete_all() was called on @X.
*/
bool completion_done(struct completion *x)
{
+ unsigned long flags;
+
if (!READ_ONCE(x->done))
return false;
@@ -307,14 +328,9 @@ bool completion_done(struct completion *x)
* If ->done, we need to wait for complete() to release ->wait.lock
* otherwise we can end up freeing the completion before complete()
* is done referencing it.
- *
- * The RMB pairs with complete()'s RELEASE of ->wait.lock and orders
- * the loads of ->done and ->wait.lock such that we cannot observe
- * the lock before complete() acquires it while observing the ->done
- * after it's acquired the lock.
*/
- smp_rmb();
- spin_unlock_wait(&x->wait.lock);
+ spin_lock_irqsave(&x->wait.lock, flags);
+ spin_unlock_irqrestore(&x->wait.lock, flags);
return true;
}
EXPORT_SYMBOL(completion_done);