public inbox for [email protected]
 help / color / mirror / Atom feed
* [PATCH] io_uring: replace smp_mb() with smp_mb__after_atomic() in io_sq_thread()
@ 2022-04-26 16:34 Almog Khaikin
  2022-04-26 17:04 ` Jens Axboe
  0 siblings, 1 reply; 2+ messages in thread
From: Almog Khaikin @ 2022-04-26 16:34 UTC (permalink / raw)
  To: axboe; +Cc: io-uring

The IORING_SQ_NEED_WAKEUP flag is now set using atomic_or() which
implies a full barrier on some architectures but it is not required to
do so. Use the more appropriate smp_mb__after_atomic() which avoids the
extra barrier on those architectures.

Signed-off-by: Almog Khaikin <[email protected]>
---
 fs/io_uring.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 72cb2d50125c..1e7466079af7 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8229,7 +8229,7 @@ static int io_sq_thread(void *data)
 				 * Ensure the store of the wakeup flag is not
 				 * reordered with the load of the SQ tail
 				 */
-				smp_mb();
+				smp_mb__after_atomic();
 
 				if (io_sqring_entries(ctx)) {
 					needs_sched = false;

base-commit: 6f07a54a90ee98ae13b37ac358624d7cc7e57850
-- 
2.36.0


^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [PATCH] io_uring: replace smp_mb() with smp_mb__after_atomic() in io_sq_thread()
  2022-04-26 16:34 [PATCH] io_uring: replace smp_mb() with smp_mb__after_atomic() in io_sq_thread() Almog Khaikin
@ 2022-04-26 17:04 ` Jens Axboe
  0 siblings, 0 replies; 2+ messages in thread
From: Jens Axboe @ 2022-04-26 17:04 UTC (permalink / raw)
  To: almogkh; +Cc: io-uring

On Tue, 26 Apr 2022 19:34:03 +0300, Almog Khaikin wrote:
> The IORING_SQ_NEED_WAKEUP flag is now set using atomic_or() which
> implies a full barrier on some architectures but it is not required to
> do so. Use the more appropriate smp_mb__after_atomic() which avoids the
> extra barrier on those architectures.
> 
> 

Applied, thanks!

[1/1] io_uring: replace smp_mb() with smp_mb__after_atomic() in io_sq_thread()
      commit: 012b7e911e69791ea518ef3d084c12cb2b8f2914

Best regards,
-- 
Jens Axboe



^ permalink raw reply	[flat|nested] 2+ messages in thread

end of thread, other threads:[~2022-04-26 17:04 UTC | newest]

Thread overview: 2+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2022-04-26 16:34 [PATCH] io_uring: replace smp_mb() with smp_mb__after_atomic() in io_sq_thread() Almog Khaikin
2022-04-26 17:04 ` Jens Axboe

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox