From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: John Stultz To: Linux Kernel Cc: John Stultz , Prarit Bhargava , stable@vger.kernel.org, Thomas Gleixner Subject: [PATCH 1/3] hrtimer: Fix clock_was_set so it is safe to call from irq context Date: Thu, 5 Jul 2012 15:12:16 -0400 Message-Id: <1341515538-5100-2-git-send-email-johnstul@us.ibm.com> In-Reply-To: <1341515538-5100-1-git-send-email-johnstul@us.ibm.com> References: <1341515538-5100-1-git-send-email-johnstul@us.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: NOTE:This is a prerequisite patch that's required to address the widely observed leap-second related futex/hrtimer issues. Currently clock_was_set() is unsafe to be called from irq context, as it calls on_each_cpu(). This causes problems when we need to adjust the time from update_wall_time(). To fix this, if clock_was_set is called when irqs are disabled, we schedule a timer to fire for immedately after we're out of interrupt context to then notify the hrtimer subsystem. CC: Prarit Bhargava CC: stable@vger.kernel.org CC: Thomas Gleixner Acked-by: Prarit Bhargava Reported-by: Jan Engelhardt Signed-off-by: John Stultz --- kernel/hrtimer.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index ae34bf5..d730678 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -746,7 +746,7 @@ static inline void retrigger_next_event(void *arg) { } * resolution timer interrupts. On UP we just disable interrupts and * call the high resolution interrupt code. */ -void clock_was_set(void) +static void do_clock_was_set(unsigned long data) { #ifdef CONFIG_HIGH_RES_TIMERS /* Retrigger the CPU local events everywhere */ @@ -755,6 +755,21 @@ void clock_was_set(void) timerfd_clock_was_set(); } +static DEFINE_TIMER(clock_was_set_timer, do_clock_was_set , 0, 0); + +void clock_was_set(void) +{ + /* + * We can't call on_each_cpu() from irq context, + * so if irqs are disabled , schedule the clock_was_set + * via a timer_list timer for right after. + */ + if (irqs_disabled()) + mod_timer(&clock_was_set_timer, jiffies); + else + do_clock_was_set(0); +} + /* * During resume we might have to reprogram the high resolution timer * interrupt (on the local CPU): -- 1.7.9.5