Commit-ID: 855a0fc30b70d6ae681badd24d6625f9a9abb787 Gitweb: http://git.kernel.org/tip/855a0fc30b70d6ae681badd24d6625f9a9abb787 Author: Frederic Weisbecker <[email protected]> AuthorDate: Tue, 17 Dec 2013 00:16:37 +0100 Committer: Frederic Weisbecker <[email protected]> CommitDate: Wed, 15 Jan 2014 23:07:11 +0100
nohz: Get timekeeping max deferment outside jiffies_lock We don't need to fetch the timekeeping max deferment under the jiffies_lock seqlock. If the clocksource is updated concurrently while we stop the tick, stop machine is called and the tick will be reevaluated again along with uptodate jiffies and its related values. Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Alex Shi <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Paul E. McKenney <[email protected]> Cc: John Stultz <[email protected]> Cc: Kevin Hilman <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Frederic Weisbecker <[email protected]> --- kernel/time/tick-sched.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index e4d0f09..68331d1 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -533,12 +533,13 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts, struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev; u64 time_delta; + time_delta = timekeeping_max_deferment(); + /* Read jiffies and the time when jiffies were updated last */ do { seq = read_seqbegin(&jiffies_lock); last_update = last_jiffies_update; last_jiffies = jiffies; - time_delta = timekeeping_max_deferment(); } while (read_seqretry(&jiffies_lock, seq)); if (rcu_needs_cpu(cpu, &rcu_delta_jiffies) || -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
