Commit 3fcf19d5 authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

io_uring: parse check_cq out of wq waiting 



We already avoid flushing overflows in io_cqring_wait_schedule() but
only return an error for the outer loop to handle it. Minimise it even
further by moving all ->check_cq parsing there.

Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/9dfcec3121013f98208dbf79368d636d74e1231a.1672916894.git.asml.silence@gmail.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 140102ae

io_uring/io_uring.c

+18 −14
Original line number Diff line number Diff line
@@ -2471,21 +2471,13 @@ static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx, 
					  ktime_t *timeout)

{

	int ret;

	unsigned long check_cq;



	if (unlikely(READ_ONCE(ctx->check_cq)))

		return 1;

	/* make sure we run task_work before checking for signals */

	ret = io_run_task_work_sig(ctx);

	if (ret || io_should_wake(iowq))

		return ret;



	check_cq = READ_ONCE(ctx->check_cq);

	if (unlikely(check_cq)) {

		/* let the caller flush overflows, retry */

		if (check_cq & BIT(IO_CHECK_CQ_OVERFLOW_BIT))

			return 1;

		if (check_cq & BIT(IO_CHECK_CQ_DROPPED_BIT))

			return -EBADR;

	}

	if (!schedule_hrtimeout(timeout, HRTIMER_MODE_ABS))

		return -ETIME;
@@ -2551,13 +2543,25 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events, 


	trace_io_uring_cqring_wait(ctx, min_events);

	do {

		if (test_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq)) {

			finish_wait(&ctx->cq_wait, &iowq.wq);

			io_cqring_do_overflow_flush(ctx);

		}

		unsigned long check_cq;



		prepare_to_wait_exclusive(&ctx->cq_wait, &iowq.wq,

						TASK_INTERRUPTIBLE);

		ret = io_cqring_wait_schedule(ctx, &iowq, &timeout);



		check_cq = READ_ONCE(ctx->check_cq);

		if (unlikely(check_cq)) {

			/* let the caller flush overflows, retry */

			if (check_cq & BIT(IO_CHECK_CQ_OVERFLOW_BIT)) {

				finish_wait(&ctx->cq_wait, &iowq.wq);

				io_cqring_do_overflow_flush(ctx);

			}

			if (check_cq & BIT(IO_CHECK_CQ_DROPPED_BIT)) {

				ret = -EBADR;

				break;

			}

		}



		if (__io_cqring_events_user(ctx) >= min_events)

			break;

		cond_resched();