* [PATCH] lib/flex_proportions.c: Remove local_irq_ops in fprop_new_period()
@ 2022-06-04 13:15 wuchi
2022-06-06 7:44 ` Jan Kara
0 siblings, 1 reply; 3+ messages in thread
From: wuchi @ 2022-06-04 13:15 UTC (permalink / raw)
To: jack, hch; +Cc: linux-kernel, akpm
The commit <e78d4833c03e28> (lib: Fix possible deadlock in flexible
proportion code) adds the local_irq_ops because percpu_counter_{sum
|add} ops'lock can cause deadlock by interrupts. Now percpu_counter
_{sum|add} ops use raw_spin_(un)lock_irq*, so revert the commit and
resolve the conflict.
Signed-off-by: wuchi <wuchi.zero@gmail.com>
---
lib/flex_proportions.c | 10 ++--------
1 file changed, 2 insertions(+), 8 deletions(-)
diff --git a/lib/flex_proportions.c b/lib/flex_proportions.c
index 53e7eb1dd76c..05cccbcf1661 100644
--- a/lib/flex_proportions.c
+++ b/lib/flex_proportions.c
@@ -63,18 +63,13 @@ void fprop_global_destroy(struct fprop_global *p)
*/
bool fprop_new_period(struct fprop_global *p, int periods)
{
- s64 events;
- unsigned long flags;
+ s64 events = percpu_counter_sum(&p->events);
- local_irq_save(flags);
- events = percpu_counter_sum(&p->events);
/*
* Don't do anything if there are no events.
*/
- if (events <= 1) {
- local_irq_restore(flags);
+ if (events <= 1)
return false;
- }
write_seqcount_begin(&p->sequence);
if (periods < 64)
events -= events >> periods;
@@ -82,7 +77,6 @@ bool fprop_new_period(struct fprop_global *p, int periods)
percpu_counter_add(&p->events, -events);
p->period += periods;
write_seqcount_end(&p->sequence);
- local_irq_restore(flags);
return true;
}
--
2.20.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] lib/flex_proportions.c: Remove local_irq_ops in fprop_new_period()
2022-06-04 13:15 [PATCH] lib/flex_proportions.c: Remove local_irq_ops in fprop_new_period() wuchi
@ 2022-06-06 7:44 ` Jan Kara
2022-06-06 7:50 ` Jan Kara
0 siblings, 1 reply; 3+ messages in thread
From: Jan Kara @ 2022-06-06 7:44 UTC (permalink / raw)
To: wuchi; +Cc: jack, hch, linux-kernel, akpm
On Sat 04-06-22 21:15:02, wuchi wrote:
> The commit <e78d4833c03e28> (lib: Fix possible deadlock in flexible
> proportion code) adds the local_irq_ops because percpu_counter_{sum
> |add} ops'lock can cause deadlock by interrupts. Now percpu_counter
> _{sum|add} ops use raw_spin_(un)lock_irq*, so revert the commit and
> resolve the conflict.
>
> Signed-off-by: wuchi <wuchi.zero@gmail.com>
Yes, good point. Thanks for cleaning this up. Feel free to add:
Reviewed-by: Jan Kara <jack@suse.cz>
I guess Andrew will pickup this patch, or should I do it Andrew?
Honza
> ---
> lib/flex_proportions.c | 10 ++--------
> 1 file changed, 2 insertions(+), 8 deletions(-)
>
> diff --git a/lib/flex_proportions.c b/lib/flex_proportions.c
> index 53e7eb1dd76c..05cccbcf1661 100644
> --- a/lib/flex_proportions.c
> +++ b/lib/flex_proportions.c
> @@ -63,18 +63,13 @@ void fprop_global_destroy(struct fprop_global *p)
> */
> bool fprop_new_period(struct fprop_global *p, int periods)
> {
> - s64 events;
> - unsigned long flags;
> + s64 events = percpu_counter_sum(&p->events);
>
> - local_irq_save(flags);
> - events = percpu_counter_sum(&p->events);
> /*
> * Don't do anything if there are no events.
> */
> - if (events <= 1) {
> - local_irq_restore(flags);
> + if (events <= 1)
> return false;
> - }
> write_seqcount_begin(&p->sequence);
> if (periods < 64)
> events -= events >> periods;
> @@ -82,7 +77,6 @@ bool fprop_new_period(struct fprop_global *p, int periods)
> percpu_counter_add(&p->events, -events);
> p->period += periods;
> write_seqcount_end(&p->sequence);
> - local_irq_restore(flags);
>
> return true;
> }
> --
> 2.20.1
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] lib/flex_proportions.c: Remove local_irq_ops in fprop_new_period()
2022-06-06 7:44 ` Jan Kara
@ 2022-06-06 7:50 ` Jan Kara
0 siblings, 0 replies; 3+ messages in thread
From: Jan Kara @ 2022-06-06 7:50 UTC (permalink / raw)
To: wuchi; +Cc: jack, hch, linux-kernel, akpm
On Mon 06-06-22 09:44:44, Jan Kara wrote:
> On Sat 04-06-22 21:15:02, wuchi wrote:
> > The commit <e78d4833c03e28> (lib: Fix possible deadlock in flexible
> > proportion code) adds the local_irq_ops because percpu_counter_{sum
> > |add} ops'lock can cause deadlock by interrupts. Now percpu_counter
> > _{sum|add} ops use raw_spin_(un)lock_irq*, so revert the commit and
> > resolve the conflict.
> >
> > Signed-off-by: wuchi <wuchi.zero@gmail.com>
>
> Yes, good point. Thanks for cleaning this up. Feel free to add:
>
> Reviewed-by: Jan Kara <jack@suse.cz>
>
> I guess Andrew will pickup this patch, or should I do it Andrew?
Oh, I can see Andrew already did pickup the patch. So everything is fine
:).
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-06-04 13:15 [PATCH] lib/flex_proportions.c: Remove local_irq_ops in fprop_new_period() wuchi
2022-06-06 7:44 ` Jan Kara
2022-06-06 7:50 ` Jan Kara
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