Commit 12521a5d authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

io_uring: fix CQ waiting timeout handling 



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: stable@vger.kernel.org
Fixes: 22833966 ("io_uring: don't convert to jiffies for waiting on timeouts")
Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/f7bffddd71b08f28a877d44d37ac953ddb01590d.1672915663.git.asml.silence@gmail.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 59b745bb

io_uring/io_uring.c

+3 −3
Original line number Diff line number Diff line
@@ -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();