On Wed, 18 Apr 2012, Santosh Shilimkar wrote: > On Wednesday 18 April 2012 06:49 PM, Shilimkar, Santosh wrote: > > On Wed, Apr 18, 2012 at 5:37 PM, tip-bot for Thomas Gleixner > > <tglx@xxxxxxxxxxxxx> wrote: > >> Commit-ID: b435092f70ec5ebbfb6d075d5bf3c631b49a51de > >> Gitweb: http://git.kernel.org/tip/b435092f70ec5ebbfb6d075d5bf3c631b49a51de > >> Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > >> AuthorDate: Wed, 18 Apr 2012 12:08:23 +0200 > >> Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > >> CommitDate: Wed, 18 Apr 2012 14:00:56 +0200 > >> > >> 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@xxxxxx> > >> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > >> Cc: Rafael J. Wysocki <rjw@xxxxxxx> > >> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> > >> Cc: Suresh Siddha <suresh.b.siddha@xxxxxxxxx> > >> Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1204181205540.2542@ionos > >> > >> --- > >> kernel/time/tick-broadcast.c | 7 +------ > >> 1 files changed, 1 insertions(+), 6 deletions(-) > >> > >> diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c > >> index bf57abd..119aca5 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); > > For some reason above if() check fails in my case, so broadcast device > never set to ONESHOT mode. That explains the problem I am seeing on > OMAP with the $subject patch. At this point of time bc->mode is > CLOCK_EVT_MODE_UNUSED. Darn, crap. I wonder how that works on x86 diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c index bf57abd..e8f5479 100644 --- a/kernel/time/tick-broadcast.c +++ b/kernel/time/tick-broadcast.c @@ -373,6 +373,9 @@ static int tick_broadcast_set_event(ktime_t expires, int force) { struct clock_event_device *bc = tick_broadcast_device.evtdev; + if (bc->mode != CLOCK_EVT_MODE_ONESHOT) + clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT); + return clockevents_program_event(bc, expires, force); } -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html