[PATCH] hrtimers: fixup itimer conversion
The itimer conversion removed the locking which protects the timer and
variables in the shared signal structure. Steven Rostedt found the problem in
the latest -rt patches.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/kernel/itimer.c b/kernel/itimer.c
index c2c05c4..6433d06 100644
--- a/kernel/itimer.c
+++ b/kernel/itimer.c
@@ -49,9 +49,11 @@
switch (which) {
case ITIMER_REAL:
+ spin_lock_irq(&tsk->sighand->siglock);
value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
value->it_interval =
ktime_to_timeval(tsk->signal->it_real_incr);
+ spin_unlock_irq(&tsk->sighand->siglock);
break;
case ITIMER_VIRTUAL:
read_lock(&tasklist_lock);
@@ -150,8 +152,14 @@
switch (which) {
case ITIMER_REAL:
+again:
+ spin_lock_irq(&tsk->sighand->siglock);
timer = &tsk->signal->real_timer;
- hrtimer_cancel(timer);
+ /* We are sharing ->siglock with it_real_fn() */
+ if (hrtimer_try_to_cancel(timer) < 0) {
+ spin_unlock_irq(&tsk->sighand->siglock);
+ goto again;
+ }
if (ovalue) {
ovalue->it_value = itimer_get_remtime(timer);
ovalue->it_interval
@@ -162,6 +170,7 @@
expires = timeval_to_ktime(value->it_value);
if (expires.tv64 != 0)
hrtimer_start(timer, expires, HRTIMER_REL);
+ spin_unlock_irq(&tsk->sighand->siglock);
break;
case ITIMER_VIRTUAL:
nval = timeval_to_cputime(&value->it_value);
