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Commit da05b5ea authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull timer fix from Ingo Molnar:
 "Fix a timer expiry bug that would cause spurious delay of timers"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  timer: Read jiffies once when forwarding base clk
parents a7b7b772 e430d802

kernel/time/timer.c

+5 −3
Original line number Diff line number Diff line
@@ -1678,24 +1678,26 @@ void timer_clear_idle(void) 
static int collect_expired_timers(struct timer_base *base,

				  struct hlist_head *heads)

{

	unsigned long now = READ_ONCE(jiffies);



	/*

	 * NOHZ optimization. After a long idle sleep we need to forward the

	 * base to current jiffies. Avoid a loop by searching the bitfield for

	 * the next expiring timer.

	 */

	if ((long)(jiffies - base->clk) > 2) {

	if ((long)(now - base->clk) > 2) {

		unsigned long next = __next_timer_interrupt(base);



		/*

		 * If the next timer is ahead of time forward to current

		 * jiffies, otherwise forward to the next expiry time:

		 */

		if (time_after(next, jiffies)) {

		if (time_after(next, now)) {

			/*

			 * The call site will increment base->clk and then

			 * terminate the expiry loop immediately.

			 */

			base->clk = jiffies;

			base->clk = now;

			return 0;

		}

		base->clk = next;