linux-kernel - [patch] high-res timers: core, do itimer rearming in process context, fix2

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Date:	Thu, 21 Dec 2006 08:15:25 +0100
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Andrew Morton <akpm@...l.org>, linux-kernel@...r.kernel.org
Subject: [patch] high-res timers: core, do itimer rearming in process
	context, fix2

Subject: [patch] high-res timers: core, do itimer rearming in process context, fix2
From: Thomas Gleixner <tglx@...utronix.de>

The rearming code in signal.c has to read the time and can not rely on
the timer->base->softirq time anymore, as it is not longer running in
softirq context.

Ensure, that the it_real_incr variable in the shared signal struct is
set to zero, when setitimer disables the itimer. Otherwise it could
happen that an inactive itimer gets rearmed by a SIGALRM.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

---
 kernel/signal.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: 2.6.19-git19/kernel/signal.c
===================================================================
--- 2.6.19-git19.orig/kernel/signal.c
+++ 2.6.19-git19/kernel/signal.c
@@ -477,7 +477,7 @@ int dequeue_signal(struct task_struct *t
 
 			if (!hrtimer_is_queued(tmr) &&
 			    tsk->signal->it_real_incr.tv64 != 0) {
-				hrtimer_forward(tmr, hrtimer_cb_get_time(tmr),
+				hrtimer_forward(tmr, tmr->base->get_time(),
 						tsk->signal->it_real_incr);
 				hrtimer_restart(tmr);
 			}
Index: 2.6.19-git19/kernel/itimer.c
===================================================================
--- 2.6.19-git19.orig/kernel/itimer.c
+++ 2.6.19-git19/kernel/itimer.c
@@ -226,11 +226,14 @@ again:
 			spin_unlock_irq(&tsk->sighand->siglock);
 			goto again;
 		}
-		tsk->signal->it_real_incr =
-			timeval_to_ktime(value->it_interval);
 		expires = timeval_to_ktime(value->it_value);
-		if (expires.tv64 != 0)
+		if (expires.tv64 != 0) {
+			tsk->signal->it_real_incr =
+				timeval_to_ktime(value->it_interval);
 			hrtimer_start(timer, expires, HRTIMER_MODE_REL);
+		} else
+			tsk->signal->it_real_incr.tv64 = 0;
+
 		spin_unlock_irq(&tsk->sighand->siglock);
 		break;
 	case ITIMER_VIRTUAL:


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