[PATCH] kernel/kthread.c: need spin_lock_irq() for 'worker' beforemain looping, since it can "WARN_ON(worker->task)".

[Chen Gang]

Since "WARN_ON(worker->task)", we can not assume that 'worker->task'
will be NULL before set 'current' to it.

So need let 'worker' lock protected too, just like it already lock
protected all time in main looping.


Signed-off-by: Chen Gang <gang.chen@xxxxxxxxxxx>
---
 kernel/kthread.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/kernel/kthread.c b/kernel/kthread.c
index 760e86d..8d572b8 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -511,8 +511,10 @@ int kthread_worker_fn(void *worker_ptr)
 	struct kthread_worker *worker = worker_ptr;
 	struct kthread_work *work;
 
+	spin_lock_irq(&worker->lock);
 	WARN_ON(worker->task);
 	worker->task = current;
+	spin_unlock_irq(&worker->lock);
 repeat:
 	set_current_state(TASK_INTERRUPTIBLE);	/* mb paired w/ kthread_stop */
 
-- 
1.7.7.6
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