On Wednesday, July 25, 2012, Colin Cross wrote: > The cpu hotplug notifier gets called in both atomic and non-atomic > contexts, it is not always safe to lock a mutex. Filter out all events > except the six necessary ones, which are all sleepable, before taking > the mutex.
I wonder what mutual exclusion mechanis we rely on when the mutex is not taken? Rafael > Signed-off-by: Colin Cross <ccr...@android.com> > --- > drivers/cpuidle/coupled.c | 12 ++++++++++++ > 1 files changed, 12 insertions(+), 0 deletions(-) > > diff --git a/drivers/cpuidle/coupled.c b/drivers/cpuidle/coupled.c > index 2c9bf26..c24dda0 100644 > --- a/drivers/cpuidle/coupled.c > +++ b/drivers/cpuidle/coupled.c > @@ -678,6 +678,18 @@ static int cpuidle_coupled_cpu_notify(struct > notifier_block *nb, > int cpu = (unsigned long)hcpu; > struct cpuidle_device *dev; > > + switch (action & ~CPU_TASKS_FROZEN) { > + case CPU_UP_PREPARE: > + case CPU_DOWN_PREPARE: > + case CPU_ONLINE: > + case CPU_DEAD: > + case CPU_UP_CANCELED: > + case CPU_DOWN_FAILED: > + break; > + default: > + return NOTIFY_OK; > + } > + > mutex_lock(&cpuidle_lock); > > dev = per_cpu(cpuidle_devices, cpu); > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/