![]() When a timer is enqueued we try to forward the timer base clock. This mechanism has two issues: 1) Forwarding a remote base unlocked The forwarding function is called from get_target_base() with the current timer base lock held. But if the new target base is a different base than the current base (can happen with NOHZ, sigh!) then the forwarding is done on an unlocked base. This can lead to corruption of base->clk. Solution is simple: Invoke the forwarding after the target base is locked. 2) Possible corruption due to jiffies advancing This is similar to the issue in get_net_timer_interrupt() which was fixed in the previous patch. jiffies can advance between check and assignement and therefore advancing base->clk beyond the next expiry value. So we need to read jiffies into a local variable once and do the checks and assignment with the local copy. Fixes: a683f390b93f("timers: Forward the wheel clock whenever possible") Reported-by: Ashton Holmes <scoopta@gmail.com> Reported-by: Michael Thayer <michael.thayer@oracle.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Michal Necasek <michal.necasek@oracle.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: knut.osmundsen@oracle.com Cc: stable@vger.kernel.org Cc: stern@rowland.harvard.edu Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20161022110552.253640125@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de> |
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.. | ||
alarmtimer.c | ||
clockevents.c | ||
clocksource.c | ||
hrtimer.c | ||
itimer.c | ||
jiffies.c | ||
Kconfig | ||
Makefile | ||
ntp.c | ||
ntp_internal.h | ||
posix-clock.c | ||
posix-cpu-timers.c | ||
posix-timers.c | ||
sched_clock.c | ||
test_udelay.c | ||
tick-broadcast-hrtimer.c | ||
tick-broadcast.c | ||
tick-common.c | ||
tick-internal.h | ||
tick-oneshot.c | ||
tick-sched.c | ||
tick-sched.h | ||
time.c | ||
timeconst.bc | ||
timeconv.c | ||
timecounter.c | ||
timekeeping.c | ||
timekeeping.h | ||
timekeeping_debug.c | ||
timekeeping_internal.h | ||
timer.c | ||
timer_list.c | ||
timer_stats.c |