timer: Warn when del_timer_sync() is called in hardirq context

Add explict warning when del_timer_sync() is called in hardirq
context.

Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 5 insertions, 1 deletions

diff --git a/kernel/timer.c b/kernel/timer.c
index 612de0306e79..483e54ba5c93 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -974,7 +974,11 @@ int del_timer_sync(struct timer_list *timer)
         lock_map_release(&timer->lockdep_map);
         local_bh_enable();
 #endif
-
+        /*
+         * don't use it in hardirq context, because it
+         * could lead to deadlock.
+         */
+        WARN_ON(in_irq());
         for (;;) {
                 int ret = try_to_del_timer_sync(timer);
                 if (ret >= 0)