* [PATCH] freezer: use smp barriers
@ 2011-04-25 7:31 Mike Frysinger
2011-04-25 8:38 ` Pavel Machek
2011-04-25 10:38 ` Rafael J. Wysocki
0 siblings, 2 replies; 3+ messages in thread
From: Mike Frysinger @ 2011-04-25 7:31 UTC (permalink / raw)
To: Pavel Machek, Rafael J. Wysocki; +Cc: linux-kernel, linux-pm
The freezer processes are dealing with multiple threads running
simultaneously, and on a UP system, the memory reads/writes do
not need barriers to keep things in sync. These are only needed
on SMP systems, so use SMP barriers instead.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
---
kernel/freezer.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/freezer.c b/kernel/freezer.c
index 66ecd2e..7b01de9 100644
--- a/kernel/freezer.c
+++ b/kernel/freezer.c
@@ -17,7 +17,7 @@ static inline void frozen_process(void)
{
if (!unlikely(current->flags & PF_NOFREEZE)) {
current->flags |= PF_FROZEN;
- wmb();
+ smp_wmb();
}
clear_freeze_flag(current);
}
@@ -93,7 +93,7 @@ bool freeze_task(struct task_struct *p, bool sig_only)
* the task as frozen and next clears its TIF_FREEZE.
*/
if (!freezing(p)) {
- rmb();
+ smp_rmb();
if (frozen(p))
return false;
--
1.7.5.rc1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] freezer: use smp barriers
2011-04-25 7:31 [PATCH] freezer: use smp barriers Mike Frysinger
@ 2011-04-25 8:38 ` Pavel Machek
2011-04-25 10:38 ` Rafael J. Wysocki
1 sibling, 0 replies; 3+ messages in thread
From: Pavel Machek @ 2011-04-25 8:38 UTC (permalink / raw)
To: Mike Frysinger; +Cc: Rafael J. Wysocki, linux-kernel, linux-pm
On Mon 2011-04-25 03:31:05, Mike Frysinger wrote:
> The freezer processes are dealing with multiple threads running
> simultaneously, and on a UP system, the memory reads/writes do
> not need barriers to keep things in sync. These are only needed
> on SMP systems, so use SMP barriers instead.
>
> Signed-off-by: Mike Frysinger <vapier@gentoo.org>
ACK.
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] freezer: use smp barriers
2011-04-25 7:31 [PATCH] freezer: use smp barriers Mike Frysinger
2011-04-25 8:38 ` Pavel Machek
@ 2011-04-25 10:38 ` Rafael J. Wysocki
1 sibling, 0 replies; 3+ messages in thread
From: Rafael J. Wysocki @ 2011-04-25 10:38 UTC (permalink / raw)
To: Mike Frysinger; +Cc: Pavel Machek, linux-kernel, linux-pm
On Monday, April 25, 2011, Mike Frysinger wrote:
> The freezer processes are dealing with multiple threads running
> simultaneously, and on a UP system, the memory reads/writes do
> not need barriers to keep things in sync. These are only needed
> on SMP systems, so use SMP barriers instead.
>
> Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Applied to suspend-2.6/linux-next.
Thanks,
Rafael
> ---
> kernel/freezer.c | 4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/freezer.c b/kernel/freezer.c
> index 66ecd2e..7b01de9 100644
> --- a/kernel/freezer.c
> +++ b/kernel/freezer.c
> @@ -17,7 +17,7 @@ static inline void frozen_process(void)
> {
> if (!unlikely(current->flags & PF_NOFREEZE)) {
> current->flags |= PF_FROZEN;
> - wmb();
> + smp_wmb();
> }
> clear_freeze_flag(current);
> }
> @@ -93,7 +93,7 @@ bool freeze_task(struct task_struct *p, bool sig_only)
> * the task as frozen and next clears its TIF_FREEZE.
> */
> if (!freezing(p)) {
> - rmb();
> + smp_rmb();
> if (frozen(p))
> return false;
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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