Messages in this thread | | | Date | Tue, 31 Jul 2012 21:13:58 +0530 | From | "Srivatsa S. Bhat" <> | Subject | Re: [PATCH] cpuidle: coupled: fix sleeping while atomic in cpu notifier |
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On 07/26/2012 02:50 AM, 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. > > Signed-off-by: Colin Cross <ccross@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; > + } > +
Instead, wouldn't it be better to have case statements for the 2 cases that imply atomic context and return immediately?
Something like: switch (action & ~CPU_TASKS_FROZEN) { case CPU_STARTING: case CPU_DYING: return NOTIFY_OK; }
Regards, Srivatsa S. Bhat
> mutex_lock(&cpuidle_lock); > > dev = per_cpu(cpuidle_devices, cpu); >
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