If thread is preempted before calling set_current_state(TASK_INTERRUPTIBLE),
and the other thread set the condition followed with wake_up_process. After
that when this thread is re-scheduled, calling set_current_state to set itself
as state TASK_INTERRUPTIBLE, if it is preempted again after that and before
__set_current_state(TASK_RUNNING), it triggers the invalid wakeup problem.
To solve this problem, using preempt_disable() to bound the operaion that
setting the task state and the conditions(set by the wake thread) validation.
Signed-off-by: Libin <huawei.li...@huawei.com>
---
kernel/trace/ring_buffer_benchmark.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/kernel/trace/ring_buffer_benchmark.c
b/kernel/trace/ring_buffer_benchmark.c
index 3c0bc03..4f43a96 100644
--- a/kernel/trace/ring_buffer_benchmark.c
+++ b/kernel/trace/ring_buffer_benchmark.c
@@ -172,6 +172,9 @@ static enum event_status read_page(int cpu)
return EVENT_FOUND;
}
+/*
+ * Called in preemptation disabled environment.
+ */
static void ring_buffer_consumer(void)
{
/* toggle between reading pages and events */
@@ -204,9 +207,12 @@ static void ring_buffer_consumer(void)
if (reader_finish)
break;
+ preempt_enable();
schedule();
__set_current_state(TASK_RUNNING);
+ preempt_disable();
}
+
reader_finish = 0;
complete(&read_done);
}
@@ -373,6 +379,7 @@ static void wait_to_die(void)
static int ring_buffer_consumer_thread(void *arg)
{
+ preempt_disable();
while (!kthread_should_stop() && !kill_test) {
complete(&read_start);
@@ -382,10 +389,13 @@ static int ring_buffer_consumer_thread(void *arg)
if (kthread_should_stop() || kill_test)
break;
+ preempt_enable();
schedule();
__set_current_state(TASK_RUNNING);
+ preempt_disable();
}
__set_current_state(TASK_RUNNING);
+ preempt_enable();
if (kill_test)
wait_to_die();
--
1.8.2.1
--
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