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io_uring: adjust smp_rmb inside io_cqring_events 

Whenever smp_rmb is required to use io_cqring_events,
keep smp_rmb inside the function io_cqring_events.

Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jackie Liu 2019-05-16 11:46:30 +08:00 committed by Jens Axboe
parent 2bbcd6d3b3
commit dc6ce4bc2b
1 changed files with 2 additions and 4 deletions
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6
fs/io_uring.c
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@ -2167,6 +2167,8 @@ static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit)
static unsigned io_cqring_events(struct io_cq_ring *ring)
{
/* See comment at the top of this file */
smp_rmb();
return READ_ONCE(ring->r.tail) - READ_ONCE(ring->r.head);
}
@ -2182,8 +2184,6 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
DEFINE_WAIT(wait);
int ret;
/* See comment at the top of this file */
smp_rmb();
if (io_cqring_events(ring) >= min_events)
return 0;
@ -2205,8 +2205,6 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
prepare_to_wait(&ctx->wait, &wait, TASK_INTERRUPTIBLE);
ret = 0;
/* See comment at the top of this file */
smp_rmb();
if (io_cqring_events(ring) >= min_events)
break;