Commit eeb60b9a authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

io_uring: refactor io_cqring_wait 



It's easy to make a mistake in io_cqring_wait() because for all
break/continue clauses we need to watch for prepare/finish_wait to be
used correctly. Extract all those into a new helper
io_cqring_wait_schedule(), and transforming the loop into simple series
of func calls: prepare(); check_and_schedule(); finish();

Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent c1d5a224

fs/io_uring.c

+22 −21
Original line number Diff line number Diff line
@@ -7195,6 +7195,25 @@ static int io_run_task_work_sig(void) 
	return -EINTR;

}



/* when returns >0, the caller should retry */

static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx,

					  struct io_wait_queue *iowq,

					  signed long *timeout)

{

	int ret;



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

	ret = io_run_task_work_sig();

	if (ret || io_should_wake(iowq))

		return ret;

	/* let the caller flush overflows, retry */

	if (test_bit(0, &ctx->cq_check_overflow))

		return 1;



	*timeout = schedule_timeout(*timeout);

	return !*timeout ? -ETIME : 1;

}



/*

 * Wait until events become available, if we don't already have some. The

 * application must reap them itself, as they reside on the shared cq ring.
@@ -7251,27 +7270,9 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events, 
		io_cqring_overflow_flush(ctx, false, NULL, NULL);

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

						TASK_INTERRUPTIBLE);

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

		ret = io_run_task_work_sig();

		if (ret > 0) {

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

			continue;

		}

		else if (ret < 0)

			break;

		if (io_should_wake(&iowq))

			break;

		if (test_bit(0, &ctx->cq_check_overflow)) {

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

			continue;

		}

		timeout = schedule_timeout(timeout);

		if (timeout == 0) {

			ret = -ETIME;

			break;

		}

	} while (1);

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

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

	} while (ret > 0);



	restore_saved_sigmask_unless(ret == -EINTR);