If thread is preempted before calling set_current_state(TASK_INTERRUPTIBLE),
and the other thread set the condition(kthread_stop). 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.
-------------
wait_to_die()
-------------
set_current_state(TASK_INTERRUPTIBLE);
while (!kthread_should_stop()) {
schedule();
set_current_state(TASK_INTERRUPTIBLE);
}
__set_current_state(TASK_RUNNING);
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.
-------------
wait_to_die()
-------------
preempt_disable();
set_current_state(TASK_INTERRUPTIBLE);
while (!kthread_should_stop()) {
preempt_enable();
schedule();
preempt_disable();
set_current_state(TASK_INTERRUPTIBLE);
}
__set_current_state(TASK_RUNNING);
preempt_enable();
Signed-off-by: Libin <huawei.li...@huawei.com>
---
kernel/trace/ring_buffer_benchmark.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/kernel/trace/ring_buffer_benchmark.c
b/kernel/trace/ring_buffer_benchmark.c
index a5457d5..3c0bc03 100644
--- a/kernel/trace/ring_buffer_benchmark.c
+++ b/kernel/trace/ring_buffer_benchmark.c
@@ -359,12 +359,16 @@ static void ring_buffer_producer(void)
static void wait_to_die(void)
{
+ preempt_disable();
set_current_state(TASK_INTERRUPTIBLE);
while (!kthread_should_stop()) {
+ preempt_enable();
schedule();
+ preempt_disable();
set_current_state(TASK_INTERRUPTIBLE);
}
__set_current_state(TASK_RUNNING);
+ preempt_enable();
}
static int ring_buffer_consumer_thread(void *arg)
--
1.8.2.1
--
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