| Message ID | 1424800730-32059-2-git-send-email-lorenzo.pieralisi@arm.com (mailing list archive) |
|---|---|
| State | Rejected, archived |
| Delegated to: | Rafael Wysocki |
| Headers | show |
On 02/24/2015 06:58 PM, Lorenzo Pieralisi wrote: > On return from cpuidle_enter_freeze() irqs are re-enabled by the function > caller (ie cpuidle_idle_call) in the idle loop. This patch removes a stale > local_irq_disable() call and its stale comment in cpuidle_enter_freeze(), > since they disagree and do not serve a useful purpose. > > Cc: Rafael J. Wysocki <rjw@rjwysocki.net> > Cc: Daniel Lezcano <daniel.lezcano@linaro.org> > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> > --- > drivers/cpuidle/cpuidle.c | 3 --- > 1 file changed, 3 deletions(-) > > diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c > index 4d53458..f47edc6c 100644 > --- a/drivers/cpuidle/cpuidle.c > +++ b/drivers/cpuidle/cpuidle.c > @@ -144,9 +144,6 @@ void cpuidle_enter_freeze(void) > cpuidle_enter(drv, dev, index); > else > arch_cpu_idle(); > - > - /* Interrupts are enabled again here. */ > - local_irq_disable(); > } Hmm, I think Rafael added this prevent lockdep to raise a warning. Otherwise, cpuidle_enter or arch_cpu_idle enables the irq again and then when exiting the cpu_idle_call, we enable them again, so leading to a lockdep WARN in trace_hardirqs_on_caller. That said, if we have to do this, it may reveal something is wrong in the code.
On Wed, Feb 25, 2015 at 02:13:23PM +0000, Daniel Lezcano wrote: > On 02/24/2015 06:58 PM, Lorenzo Pieralisi wrote: > > On return from cpuidle_enter_freeze() irqs are re-enabled by the function > > caller (ie cpuidle_idle_call) in the idle loop. This patch removes a stale > > local_irq_disable() call and its stale comment in cpuidle_enter_freeze(), > > since they disagree and do not serve a useful purpose. > > > > Cc: Rafael J. Wysocki <rjw@rjwysocki.net> > > Cc: Daniel Lezcano <daniel.lezcano@linaro.org> > > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> > > --- > > drivers/cpuidle/cpuidle.c | 3 --- > > 1 file changed, 3 deletions(-) > > > > diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c > > index 4d53458..f47edc6c 100644 > > --- a/drivers/cpuidle/cpuidle.c > > +++ b/drivers/cpuidle/cpuidle.c > > @@ -144,9 +144,6 @@ void cpuidle_enter_freeze(void) > > cpuidle_enter(drv, dev, index); > > else > > arch_cpu_idle(); > > - > > - /* Interrupts are enabled again here. */ > > - local_irq_disable(); > > } > > Hmm, I think Rafael added this prevent lockdep to raise a warning. Ok, so the comment is there to say "at this point of execution IRQs are enabled", it does not refer to local_irq_disable() call effects, that's misleading and not necessarily nice, at least it should be explained. > Otherwise, cpuidle_enter or arch_cpu_idle enables the irq again and then > when exiting the cpu_idle_call, we enable them again, so leading to a > lockdep WARN in trace_hardirqs_on_caller. Would not it be better to enable irqs in cpuidle_enter_freeze() on returning from enter_freeze_proper() and remove the local_irq_enable() call in the cpuidle_idle_call() before jumping to exit_idle ? > That said, if we have to do this, it may reveal something is wrong in > the code. I just spotted code through inspection, I have to say at the moment it is not very clear what it is meant to achieve, so I put together this patch. Lorenzo -- 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 4d53458..f47edc6c 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -144,9 +144,6 @@ void cpuidle_enter_freeze(void) cpuidle_enter(drv, dev, index); else arch_cpu_idle(); - - /* Interrupts are enabled again here. */ - local_irq_disable(); } /**
On return from cpuidle_enter_freeze() irqs are re-enabled by the function caller (ie cpuidle_idle_call) in the idle loop. This patch removes a stale local_irq_disable() call and its stale comment in cpuidle_enter_freeze(), since they disagree and do not serve a useful purpose. Cc: Rafael J. Wysocki <rjw@rjwysocki.net> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> --- drivers/cpuidle/cpuidle.c | 3 --- 1 file changed, 3 deletions(-)