From: Pavel Begunkov <asml.silence@gmail.com>
Date: Mon, 25 Jan 2021 11:42:20 +0000 (+0000)
Subject: io_uring: ensure only sqo_task has file notes
X-Git-Tag: accepted/tizen/unified/20230118.172025~7716^2~98
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=ecfc8492820732be652146280912554ced62c32b;p=platform%2Fkernel%2Flinux-rpi.git

io_uring: ensure only sqo_task has file notes

For SQPOLL io_uring we want to have only one file note held by
sqo_task. Add a warning to make sure it holds. It's deep in
io_uring_add_task_file() out of hot path, so shouldn't hurt.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/fs/io_uring.c b/fs/io_uring.c
index b05d374..68bf2c8 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -9099,6 +9099,10 @@ static int io_uring_add_task_file(struct io_ring_ctx *ctx, struct file *file)
 				fput(file);
 				return ret;
 			}
+
+			/* one and only SQPOLL file note, held by sqo_task */
+			WARN_ON_ONCE((ctx->flags & IORING_SETUP_SQPOLL) &&
+				     current != ctx->sqo_task);
 		}
 		tctx->last = file;
 	}