Re: [PATCH 4/4] vtime: No need to disable irqs on vtime_account()

From: Frederic Weisbecker
Date: Wed Nov 14 2012 - 14:41:10 EST


2012/11/14 Steven Rostedt <rostedt@xxxxxxxxxxx>:
> On Wed, 2012-11-14 at 17:26 +0100, Frederic Weisbecker wrote:
>> vtime_account() is only called from irq entry. irqs
>> are always disabled at this point so we can safely
>> remove the irq disabling guards on that function.
>>
>> Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
>> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
>> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
>> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
>> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
>> Cc: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
>> Cc: Tony Luck <tony.luck@xxxxxxxxx>
>> Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
>> Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
>> Cc: Paul Mackerras <paulus@xxxxxxxxx>
>> Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
>> Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
>> ---
>> kernel/sched/cputime.c | 6 ------
>> 1 files changed, 0 insertions(+), 6 deletions(-)
>>
>> diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
>> index 2e8d34a..80b2fd5 100644
>> --- a/kernel/sched/cputime.c
>> +++ b/kernel/sched/cputime.c
>> @@ -467,16 +467,10 @@ void vtime_task_switch(struct task_struct *prev)
>> #ifndef __ARCH_HAS_VTIME_ACCOUNT
>> void vtime_account(struct task_struct *tsk)
>> {
>> - unsigned long flags;
>> -
>> - local_irq_save(flags);
>> -
>
> I'd add a WARN_ON_ONCE(!irqs_disabled()) again here, or is this also
> covered by the vtime_delta()?

Yeah it's the ending point for both vtime_account_system() and
vtime_account_idle()
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