lkml.org 
[lkml]   [2011]   [Feb]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
SubjectRe: [PATCH v2] oprofile: add SMP barriers for hrtimer hotplug code
From
Date
On Tue, 2011-02-01 at 08:03 +0000, Ming Lei wrote:
> Hi,
>
Hello Lei Ming,

> 2011/2/1 Santosh Shilimkar <santosh.shilimkar@ti.com>:
> >> -----Original Message-----
> >> From: Will Deacon [mailto:will.deacon@arm.com]
> >> diff --git a/drivers/oprofile/timer_int.c
> >> b/drivers/oprofile/timer_int.c
> >> index 0107251..a3a94ea 100644
> >> --- a/drivers/oprofile/timer_int.c
> >> +++ b/drivers/oprofile/timer_int.c
> >> @@ -48,6 +48,7 @@ static int oprofile_hrtimer_start(void)
> >> {
> >> get_online_cpus();
> >> ctr_running = 1;
> >> + smp_mb();
> >> on_each_cpu(__oprofile_hrtimer_start, NULL, 1);
>
> Just a little question:
>
> Before calling __oprofile_hrtimer_start in other CPUs,
> there have been some smp_mb executed already, such as called by
> smp_call_function_many in current CPU, and called by
> generic_smp_call_function_interrupt in the func-calling CPU,
> so are these smp_mb enough for correct order of access
> for 'ctr_running' ?

I didn't dive into the guts of the cross-calling implementation, but it
appears that you're correct. There's also the csd_{un}lock functions
which have smp_mb() in them too, so I think we have plenty of barrier
goodness as it is.

I'll trash the patch.

Cheers,

Will



\
 
 \ /
  Last update: 2011-02-01 18:11    [W:0.034 / U:12.820 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site