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authorThomas Gleixner <tglx@linutronix.de>2012-04-18 12:08:23 +0200
committerThomas Gleixner <tglx@linutronix.de>2012-04-18 14:00:56 +0200
commitb435092f70ec5ebbfb6d075d5bf3c631b49a51de (patch)
treec9cfd15c405dd218003fd84585196b5bffcc9bbd /kernel
parent592fe8980688e7cba46897685d014c7fb3018a67 (diff)
downloadlinux-b435092f70ec5ebbfb6d075d5bf3c631b49a51de.tar.gz
tick: Fix oneshot broadcast setup really
Sven Joachim reported, that suspend/resume on rc3 trips over a NULL pointer dereference. Linus spotted the clockevent handler being NULL. commit fa4da365b(clockevents: tTack broadcast device mode change in tick_broadcast_switch_to_oneshot()) tried to fix a problem with the broadcast device setup, which was introduced in commit 77b0d60c5( clockevents: Leave the broadcast device in shutdown mode when not needed). The initial commit avoided to set up the broadcast device when no broadcast request bits were set, but that left the broadcast device disfunctional. In consequence deep idle states which need the broadcast device were not woken up. commit fa4da365b tried to fix that by initializing the state of the broadcast facility, but that missed the fact, that nothing initializes the event handler and some other state of the underlying clock event device. The fix is to revert both commits and make only the mode setting of the clock event device conditional on the state of active broadcast users. That initializes everything except the low level device mode, but this happens when the broadcast functionality is invoked by deep idle. Reported-and-tested-by: Sven Joachim <svenjoac@gmx.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Rafael J. Wysocki <rjw@sisk.pl> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Suresh Siddha <suresh.b.siddha@intel.com> Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1204181205540.2542@ionos
Diffstat (limited to 'kernel')
-rw-r--r--kernel/time/tick-broadcast.c7
1 files changed, 1 insertions, 6 deletions
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index bf57abdc7bd..119aca5c684 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -531,7 +531,6 @@ void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
int was_periodic = bc->mode == CLOCK_EVT_MODE_PERIODIC;
bc->event_handler = tick_handle_oneshot_broadcast;
- clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
/* Take the do_timer update */
tick_do_timer_cpu = cpu;
@@ -549,6 +548,7 @@ void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
to_cpumask(tmpmask));
if (was_periodic && !cpumask_empty(to_cpumask(tmpmask))) {
+ clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
tick_broadcast_init_next_event(to_cpumask(tmpmask),
tick_next_period);
tick_broadcast_set_event(tick_next_period, 1);
@@ -577,15 +577,10 @@ void tick_broadcast_switch_to_oneshot(void)
raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
-
- if (cpumask_empty(tick_get_broadcast_mask()))
- goto end;
-
bc = tick_broadcast_device.evtdev;
if (bc)
tick_broadcast_setup_oneshot(bc);
-end:
raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
}