linux-kernel - [PATCH 5.15 133/917] io_uring: honour zeroes as io-wq worker limits

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Message-Id: <20211115165433.281797198@linuxfoundation.org>
Date:   Mon, 15 Nov 2021 17:53:48 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Beld Zhang <beldzhang@...il.com>,
        Pavel Begunkov <asml.silence@...il.com>,
        Jens Axboe <axboe@...nel.dk>, stable@...nel.org
Subject: [PATCH 5.15 133/917] io_uring: honour zeroes as io-wq worker limits

From: Pavel Begunkov <asml.silence@...il.com>

commit bad119b9a00019054f0c9e2045f312ed63ace4f4 upstream.

When we pass in zero as an io-wq worker number limit it shouldn't
actually change the limits but return the old value, follow that
behaviour with deferred limits setup as well.

Cc: stable@...nel.org # 5.15
Reported-by: Beld Zhang <beldzhang@...il.com>
Fixes: e139a1ec92f8d ("io_uring: apply max_workers limit to all future users")
Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
Link: https://lore.kernel.org/r/1b222a92f7a78a24b042763805e891a4cdd4b544.1636384034.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/io_uring.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -10684,7 +10684,9 @@ static int io_register_iowq_max_workers(
 
 	BUILD_BUG_ON(sizeof(new_count) != sizeof(ctx->iowq_limits));
 
-	memcpy(ctx->iowq_limits, new_count, sizeof(new_count));
+	for (i = 0; i < ARRAY_SIZE(new_count); i++)
+		if (new_count[i])
+			ctx->iowq_limits[i] = new_count[i];
 	ctx->iowq_limits_set = true;
 
 	ret = -EINVAL;