[linux-pm] [RFC/PATCH v2] PM / Runtime: allow _put_sync() from interrupts-disabled context
Rafael J. Wysocki
rjw at sisk.pl
Wed Jul 27 05:22:07 EDT 2011
On Wednesday, July 27, 2011, Kevin Hilman wrote:
> "Rafael J. Wysocki" <rjw at sisk.pl> writes:
> > On Friday, July 22, 2011, Kevin Hilman wrote:
> >> Currently the use of pm_runtime_put_sync() is not safe from
> >> interrupts-disabled context because rpm_idle() will release the
> >> spinlock and enable interrupts for the idle callbacks. This enables
> >> interrupts during a time where interrupts were expected to be
> >> disabled, and can have strange side effects on drivers that expected
> >> interrupts to be disabled.
> >> This is not a bug since the documentation clearly states that only
> >> _put_sync_suspend() is safe in IRQ-safe mode.
> >> However, pm_runtime_put_sync() could be made safe when in IRQ-safe
> >> mode by releasing the spinlock but not re-enabling interrupts, which
> >> is what this patch aims to do.
> >> Problem was found when using some buggy drivers that set
> >> pm_runtime_irq_safe() and used _put_sync() in interrupts-disabled
> >> context.
> >> The offending drivers have been fixed to use _put_sync_suspend(),
> >> But this patch is an RFC to see if it might make sense to allow
> >> using _put_sync() from interrupts-disabled context.
> > OK, I'm going to take this for 3.2.
> OK, great. Thanks.
> Might want to just drop the last paragraph from the changelog since it
> doesn't really belong in the permanant history.
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