[PATCH] ITIMER_REAL: fix possible deadlock and race

[linux-2.6-omap-h63xx.git] / kernel / itimer.c

diff --git a/kernel/itimer.c b/kernel/itimer.c
index 1dc988e0d2c77e962063c776b7b035800f51b9be..a72cb0e5aa4b5d6f94764e128e4f376f0dc6591e 100644 (file)
--- a/kernel/itimer.c
+++ b/kernel/itimer.c
@@ -153,11 +153,15 @@ int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
 
        switch (which) {
        case ITIMER_REAL:
+again:
                spin_lock_irq(&tsk->sighand->siglock);
                interval = tsk->signal->it_real_incr;
                val = it_real_value(tsk->signal);
-               if (val)
-                       del_timer_sync(&tsk->signal->real_timer);
+               /* We are sharing ->siglock with it_real_fn() */
+               if (try_to_del_timer_sync(&tsk->signal->real_timer) < 0) {
+                       spin_unlock_irq(&tsk->sighand->siglock);
+                       goto again;
+               }
                tsk->signal->it_real_incr =
                        timeval_to_jiffies(&value->it_interval);
                it_real_arm(tsk, timeval_to_jiffies(&value->it_value));