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 <[email protected]> > > Cc: Daniel Lezcano <[email protected]> > > Signed-off-by: Lorenzo Pieralisi <[email protected]> > > --- > > 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-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
