| Message ID | 1453375169-14768-1-git-send-email-sudeep.holla@arm.com |
|---|---|
| State | New |
| Headers | show |
On 22/01/16 01:15, Rafael J. Wysocki wrote: > 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" <rjw@rjwysocki.net> >> Cc: Ingo Molnar <mingo@redhat.com> >> Cc: Peter Zijlstra <peterz@infradead.org> >> Signed-off-by: Sudeep Holla <sudeep.holla@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. > Sorry that I missed to test suspend-to-idle before it got merged. >> 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. > Even on ARM, 0 is used for WFI only, which will not be used for freeze. > If you think we can also make 0 a special case on ARM, the others should > not object to that either. > Makes sense and since it's already reserved for WFI on ARM, it should be fine. If there are no objections, can you pick up this fix ? -- Regards, Sudeep -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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; }
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" <rjw@rjwysocki.net> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> --- drivers/cpuidle/cpuidle.c | 2 +- kernel/sched/idle.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) Hi Rafael, 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 ? Regards, Sudeep -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html