Messages in this thread | | | Date | Wed, 01 Aug 2012 11:29:50 +0530 | From | "Srivatsa S. Bhat" <> | Subject | Re: [PATCH] cpuidle: coupled: fix sleeping while atomic in cpu notifier |
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On 07/31/2012 11:57 PM, Colin Cross wrote: > On Tue, Jul 31, 2012 at 8:43 AM, Srivatsa S. Bhat > <srivatsa.bhat@linux.vnet.ibm.com> wrote: >> 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; >> } > > No, because then it would need updating whenever a new notification > event was added. >
Hmm.. Fair enough.
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Regards, Srivatsa S. Bhat
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