Commit 50470fc5 authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

io_uring: return normal tw run linking optimisation 



io_submit_flush_completions() may produce new task_work items, so it's a
good idea to recheck the task_work list after flushing completions. The
optimisation is not new and was accidentially removed by
f88262e6 ("io_uring: lockless task list")

Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/a7ed5ede84de190832cc33ebbcdd6e91cd90f5b6.1674484266.git.asml.silence@gmail.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent cb6bf7f2

io_uring/io_uring.c

+9 −0
Original line number Diff line number Diff line
@@ -1238,6 +1238,15 @@ void tctx_task_work(struct callback_head *cb) 
		loops++;

		node = io_llist_xchg(&tctx->task_list, &fake);

		count += handle_tw_list(node, &ctx, &uring_locked, &fake);



		/* skip expensive cmpxchg if there are items in the list */

		if (READ_ONCE(tctx->task_list.first) != &fake)

			continue;

		if (uring_locked && !wq_list_empty(&ctx->submit_state.compl_reqs)) {

			io_submit_flush_completions(ctx);

			if (READ_ONCE(tctx->task_list.first) != &fake)

				continue;

		}

		node = io_llist_cmpxchg(&tctx->task_list, &fake, NULL);

	} while (node != &fake);