From 4e214e7e01158a87308a17766706159bca472855 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@kernel.dk>
Date: Mon, 17 Jul 2023 10:27:20 -0600
Subject: [PATCH 2/2] io_uring: add reschedule point to handle_tw_list()

Commit f58680085478dd292435727210122960d38e8014 upstream.

If CONFIG_PREEMPT_NONE is set and the task_work chains are long, we
could be running into issues blocking others for too long. Add a
reschedule check in handle_tw_list(), and flush the ctx if we need to
reschedule.

Cc: stable@vger.kernel.org # 5.10+
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 io_uring/io_uring.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 33d4a2871dbb..eae7a3d89397 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -2216,9 +2216,12 @@ static void tctx_task_work(struct callback_head *cb)
 			}
 			req->io_task_work.func(req, &locked);
 			node = next;
+			if (unlikely(need_resched())) {
+				ctx_flush_and_put(ctx, &locked);
+				ctx = NULL;
+				cond_resched();
+			}
 		} while (node);
-
-		cond_resched();
 	}
 
 	ctx_flush_and_put(ctx, &locked);
-- 
2.40.1

