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* [PATCH v2] io_uring: fix CQ waiting timeout handling
@ 2023-01-05 10:49 Pavel Begunkov
  2023-01-11  6:39 ` Xiaoguang Wang
  0 siblings, 1 reply; 4+ messages in thread
From: Pavel Begunkov @ 2023-01-05 10:49 UTC (permalink / raw)
  To: io-uring; +Cc: Jens Axboe, asml.silence

Jiffy to ktime CQ waiting conversion broke how we treat timeouts, in
particular we rearm it anew every time we get into
io_cqring_wait_schedule() without adjusting the timeout. Waiting for 2
CQEs and getting a task_work in the middle may double the timeout value,
or even worse in some cases task may wait indefinitely.

Cc: [email protected]
Fixes: 228339662b398 ("io_uring: don't convert to jiffies for waiting on timeouts")
Signed-off-by: Pavel Begunkov <[email protected]>
---

v2: rebase

 io_uring/io_uring.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 472574192dd6..2ac1cd8d23ea 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -2470,7 +2470,7 @@ int io_run_task_work_sig(struct io_ring_ctx *ctx)
 /* when returns >0, the caller should retry */
 static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx,
 					  struct io_wait_queue *iowq,
-					  ktime_t timeout)
+					  ktime_t *timeout)
 {
 	int ret;
 	unsigned long check_cq;
@@ -2488,7 +2488,7 @@ static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx,
 		if (check_cq & BIT(IO_CHECK_CQ_DROPPED_BIT))
 			return -EBADR;
 	}
-	if (!schedule_hrtimeout(&timeout, HRTIMER_MODE_ABS))
+	if (!schedule_hrtimeout(timeout, HRTIMER_MODE_ABS))
 		return -ETIME;
 
 	/*
@@ -2564,7 +2564,7 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
 		}
 		prepare_to_wait_exclusive(&ctx->cq_wait, &iowq.wq,
 						TASK_INTERRUPTIBLE);
-		ret = io_cqring_wait_schedule(ctx, &iowq, timeout);
+		ret = io_cqring_wait_schedule(ctx, &iowq, &timeout);
 		if (__io_cqring_events_user(ctx) >= min_events)
 			break;
 		cond_resched();
-- 
2.38.1


^ permalink raw reply related	[flat|nested] 4+ messages in thread
* Re: [PATCH v2] io_uring: fix CQ waiting timeout handling
@ 2023-01-05 15:05 Jens Axboe
  0 siblings, 0 replies; 4+ messages in thread
From: Jens Axboe @ 2023-01-05 15:05 UTC (permalink / raw)
  To: io-uring, Pavel Begunkov


On Thu, 05 Jan 2023 10:49:15 +0000, Pavel Begunkov wrote:
> Jiffy to ktime CQ waiting conversion broke how we treat timeouts, in
> particular we rearm it anew every time we get into
> io_cqring_wait_schedule() without adjusting the timeout. Waiting for 2
> CQEs and getting a task_work in the middle may double the timeout value,
> or even worse in some cases task may wait indefinitely.
> 
> 
> [...]

Applied, thanks!

[1/1] io_uring: fix CQ waiting timeout handling
      commit: 12521a5d5cb7ff0ad43eadfc9c135d86e1131fa8

Best regards,
-- 
Jens Axboe



^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2023-01-11 14:46 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
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2023-01-05 10:49 [PATCH v2] io_uring: fix CQ waiting timeout handling Pavel Begunkov
2023-01-11  6:39 ` Xiaoguang Wang
2023-01-11 14:44   ` Pavel Begunkov
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2023-01-05 15:05 Jens Axboe

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