PM / Runtime: Allow _put_sync() from interrupts-disabled context
authorKevin Hilman <khilman@ti.com>
Fri, 5 Aug 2011 19:45:20 +0000 (21:45 +0200)
committerRafael J. Wysocki <rjw@sisk.pl>
Fri, 5 Aug 2011 19:45:20 +0000 (21:45 +0200)
commit02b26774afebb2d62695ba3230319d70d8c6cc2d
tree956c4056fcb42d2c2b2a75e20d3ad98f148865fc
parentfe202fde50a986a8510c62a76dc8733c1a8fac86
PM / Runtime: Allow _put_sync() from interrupts-disabled context

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.

Reported-by: Colin Cross <ccross@google.com>
Tested-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Documentation/power/runtime_pm.txt
drivers/base/power/runtime.c