Patch "io_uring: refactor scheduling in io_cqring_wait" has been added to the 5.11-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    io_uring: refactor scheduling in io_cqring_wait

to the 5.11-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     io_uring-refactor-scheduling-in-io_cqring_wait.patch
and it can be found in the queue-5.11 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 03fc298d186de3b2ce9936c6112c21f03ddd76f2
Author: Pavel Begunkov <asml.silence@xxxxxxxxx>
Date:   Thu Feb 4 13:51:57 2021 +0000

    io_uring: refactor scheduling in io_cqring_wait
    
    [ Upstream commit c1d5a224683b333ddbe278e455d639ccd4f5ca2b ]
    
    schedule_timeout() with timeout=MAX_SCHEDULE_TIMEOUT is guaranteed to
    work just as schedule(), so instead of hand-coding it based on arguments
    always use the timeout version and simplify code.
    
    Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
    Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 68508f010b90..3e610ac062a3 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -7226,9 +7226,8 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
 		.to_wait	= min_events,
 	};
 	struct io_rings *rings = ctx->rings;
-	struct timespec64 ts;
-	signed long timeout = 0;
-	int ret = 0;
+	signed long timeout = MAX_SCHEDULE_TIMEOUT;
+	int ret;
 
 	do {
 		io_cqring_overflow_flush(ctx, false, NULL, NULL);
@@ -7252,6 +7251,8 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
 	}
 
 	if (uts) {
+		struct timespec64 ts;
+
 		if (get_timespec64(&ts, uts))
 			return -EFAULT;
 		timeout = timespec64_to_jiffies(&ts);
@@ -7277,14 +7278,10 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
 			finish_wait(&ctx->wait, &iowq.wq);
 			continue;
 		}
-		if (uts) {
-			timeout = schedule_timeout(timeout);
-			if (timeout == 0) {
-				ret = -ETIME;
-				break;
-			}
-		} else {
-			schedule();
+		timeout = schedule_timeout(timeout);
+		if (timeout == 0) {
+			ret = -ETIME;
+			break;
 		}
 	} while (1);
 	finish_wait(&ctx->wait, &iowq.wq);