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SubjectRe: Long timeout when booting >= 2.6.38
On Sun, 15 May 2011, Christian Hoffmann wrote:
> new trace:
> http://dl.dropbox.com/u/21820416/traceing2.log.bz2
>
> Sorry for delay.

Nothing to be sorry about. Thanks for providing the information. If I
decoded the problem correctly then this just unearthed a real long
standing bug. Does the patch below solve the problem ?

Thanks,

tglx

--- linux-2.6.orig/kernel/time/tick-broadcast.c
+++ linux-2.6/kernel/time/tick-broadcast.c
@@ -522,10 +522,11 @@ static void tick_broadcast_init_next_eve
*/
void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
{
+ int cpu = smp_processor_id();
+
/* Set it up only once ! */
if (bc->event_handler != tick_handle_oneshot_broadcast) {
int was_periodic = bc->mode == CLOCK_EVT_MODE_PERIODIC;
- int cpu = smp_processor_id();

bc->event_handler = tick_handle_oneshot_broadcast;
clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
@@ -551,6 +552,15 @@ void tick_broadcast_setup_oneshot(struct
tick_broadcast_set_event(tick_next_period, 1);
} else
bc->next_event.tv64 = KTIME_MAX;
+ } else {
+ /*
+ * The first cpu which switches to oneshot mode sets
+ * the bit for all other cpus which are in the general
+ * (periodic) broadcast mask. So the bit is set and
+ * would prevent the first broadcast enter after this
+ * to program the bc device.
+ */
+ tick_broadcast_clear_oneshot(cpu);
}
}


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