From: Steven [email protected] <[email protected]>
Date: 1137711149 +0100
CPU0 expires a posix-timer and runs the callback function.
The signal is queued.
After releasing the posix-timer lock and before returning to
hrtimer_run_queue CPU0 gets interrupted.
CPU1 delivers the queued signal and rearms the timer.
CPU0 comes back to hrtimer_run_queue and sets the timer state to expired.
The next modification of the timer can result in an oops, because the state
information is wrong.
Keep track of state = RUNNING and check if the state has been in the return
path of hrtimer_run_queue. In case the state has been changed, ignore a
restart request and do not touch the state variable.
Signed-off-by: Steven Rostedt <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
---
include/linux/hrtimer.h | 1 +
kernel/hrtimer.c | 5 +++++
2 files changed, 6 insertions(+), 0 deletions(-)
7a42511f275d3c895be54f4e578921fc35e25dd2
diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index 089bfb1..c657f3d 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -40,6 +40,7 @@ enum hrtimer_restart {
enum hrtimer_state {
HRTIMER_INACTIVE, /* Timer is inactive */
HRTIMER_EXPIRED, /* Timer is expired */
+ HRTIMER_RUNNING, /* Timer is running the callback function */
HRTIMER_PENDING, /* Timer is pending */
};
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index f1c4155..f580dd9 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -550,6 +550,7 @@ static inline void run_hrtimer_queue(str
fn = timer->function;
data = timer->data;
set_curr_timer(base, timer);
+ timer->state = HRTIMER_RUNNING;
__remove_hrtimer(timer, base);
spin_unlock_irq(&base->lock);
@@ -565,6 +566,10 @@ static inline void run_hrtimer_queue(str
spin_lock_irq(&base->lock);
+ /* Another CPU has added back the timer */
+ if (timer->state != HRTIMER_RUNNING)
+ continue;
+
if (restart == HRTIMER_RESTART)
enqueue_hrtimer(timer, base);
else
--
1.0.8
--
-
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