From b4f20bb4e6d55a971d5f5555a971978a6263d8de Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@kernel.dk>
Date: Fri, 25 Mar 2022 16:39:57 -0600
Subject: [PATCH] io_uring: move finish_wait() outside of loop in cqring_wait()
Git-commit: b4f20bb4e6d55a971d5f5555a971978a6263d8de
Patch-mainline: v5.19-rc1
References: bsc#1205205

We don't need to call this for every loop. This is particularly
troublesome if we are task_work intensive, and get woken more often than
we desire due to that.

Just do it at the end, that's always safe as we initialize the waitqueue
list head anyway. This can save a considerable amount of hammering on
the waitqueue lock, which is also hot from the request completion side.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>
---
 fs/io_uring.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 007dc1c14af4..ed3f26259122 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8174,10 +8174,10 @@ 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);
-		finish_wait(&ctx->cq_wait, &iowq.wq);
 		cond_resched();
 	} while (ret > 0);
 
+	finish_wait(&ctx->cq_wait, &iowq.wq);
 	restore_saved_sigmask_unless(ret == -EINTR);
 
 	return READ_ONCE(rings->cq.head) == READ_ONCE(rings->cq.tail) ? ret : 0;
-- 
2.35.3