On Thursday, January 21, 2016 11:19:29 AM Sudeep Holla wrote: > Commit 51164251f5c3 ("sched / idle: Drop default_idle_call() fallback > from call_cpuidle()") made find_deepest_state() return non-negative > value and check all the states with index > 0. Also a result, > find_deepest_state() returns 0 even when enter_freeze callbacks are not > implemented and enter_freeze_proper is called which ends up crashing > the kernel. > > This patch updates the check for index > 0 in cpuidle_enter_freeze and > cpuidle_idle_call(when idle_should_freeze is true) to restore the > suspend-to-idle functionality in absence of enter_freeze callback. > > Fixes: 51164251f5c3 ("sched / idle: Drop default_idle_call() fallback from > call_cpuidle()") > Cc: "Rafael J. Wysocki" <r...@rjwysocki.net> > Cc: Ingo Molnar <mi...@redhat.com> > Cc: Peter Zijlstra <pet...@infradead.org> > Signed-off-by: Sudeep Holla <sudeep.ho...@arm.com> > --- > drivers/cpuidle/cpuidle.c | 2 +- > kernel/sched/idle.c | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) > > Hi Rafael,
Hi, Sorry for the breakage. > I assume you prefer to retain find_deepest_state return non-negative > values, so I took this approach for fixing the bug. Do you think we > need to support enter_freeze_proper for index 0 ? Zero is a special case on x86, so supporting enter_freeze_proper() for it is not necessary. If you think we can also make 0 a special case on ARM, the others should not object to that either. > diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c > index 046423b0c5ca..f996efc56605 100644 > --- a/drivers/cpuidle/cpuidle.c > +++ b/drivers/cpuidle/cpuidle.c > @@ -153,7 +153,7 @@ int cpuidle_enter_freeze(struct cpuidle_driver *drv, > struct cpuidle_device *dev) > * be frozen safely. > */ > index = find_deepest_state(drv, dev, UINT_MAX, 0, true); > - if (index >= 0) > + if (index > 0) > enter_freeze_proper(drv, dev, index); > > return index; > diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c > index de0e786b2667..544a7133cbd1 100644 > --- a/kernel/sched/idle.c > +++ b/kernel/sched/idle.c > @@ -162,7 +162,7 @@ static void cpuidle_idle_call(void) > */ > if (idle_should_freeze()) { > entered_state = cpuidle_enter_freeze(drv, dev); > - if (entered_state >= 0) { > + if (entered_state > 0) { > local_irq_enable(); > goto exit_idle; > } > -- > 1.9.1 > Thanks, Rafael