Commit-ID: adf374cf61394dd41c027c74a81f9bef90f7a640
Gitweb: http://git.kernel.org/tip/adf374cf61394dd41c027c74a81f9bef90f7a640
Author: John Stultz <johnstul@xxxxxxxxxx>
AuthorDate: Thu, 5 Jul 2012 15:12:16 -0400
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Mon, 9 Jul 2012 11:35:38 +0200
hrtimer: Fix clock_was_set so it is safe to call from irq context
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.
Reported-by: Jan Engelhardt <jengelh@xxxxxxx>
Signed-off-by: John Stultz <johnstul@xxxxxxxxxx>
Acked-by: Prarit Bhargava <prarit@xxxxxxxxxx>
CC: stable@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/1341515538-5100-2-git-send-email-johnstul@xxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
kernel/hrtimer.c | 17 ++++++++++++++++-
1 files changed, 16 insertions(+), 1 deletions(-)
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):
--
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