From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 934BF2F10A3; Mon, 5 May 2025 23:23:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746487435; cv=none; b=AE6Kh7Sj2FTPeyPVLrfBHLykmCg/y+KzsQGY2LCGYgq6nz2iolZo/VIgXZV661zws6DoxfboRx3vBPynjyxHq4BVzPzWulEjlQ6bJhRzkMS8UIM84lGd7BamUBW0vEKyVzqiTmLpb1n9Sy87re2W97FS4su6bvupErWb2HL+Vds= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746487435; c=relaxed/simple; bh=Xqo5iZ4YGVxrB/Rap8N1HtW9HTVyu1H5uyH8lcgaPPQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=tKEDLkLPDvtRpgsY9wVEQTLVxsFvPW75jBzup4nJA9XJ7lvH4ddXjErE2mrZGkxXv03DsEKJhd2HUIBjjXNa68qKJI990rG5nfPRTjGO+QSrp7MaaSDoLzsO8kWfJX1bkSaBgd76m55Xj0phw7eVGih6dk3Jf02Q+2ThF91nz30= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=s+Uidgvn; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="s+Uidgvn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D019FC4CEED; Mon, 5 May 2025 23:23:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746487434; bh=Xqo5iZ4YGVxrB/Rap8N1HtW9HTVyu1H5uyH8lcgaPPQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=s+UidgvnIT1ExCwe+1KvCS7WGDMJUoZFaleqdkLzOMsa0KUSwuQ2nYIV/izxYPco/ u+u1rz6fqS3k2s77dxX0EAfWM+0z6F0r4GITc6DS9pEhAHOBnT1gmWEpRj02UWOf/j c2uJxdivejAJBtVdT40QRxr5cfXDylwyd+bYlvqejb5tPFNNhczqw1XX/Kgrj9nnN+ Y1Swo8jdXFEXiZ0BgkPhHQopx1ar5m5eFS3o+qb1xlTVJOvaYYc8ltPPS89rQ20REk DGixy+f+P0uT+n7VR0O57D3HXBRcWBSuDrTAfTEsk5rg8nEx4AxCPJYuMUE+yGy05L jikEmw/Vudg9A== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Antoine Tenart , Jakub Kicinski , Sasha Levin , davem@davemloft.net, edumazet@google.com, pabeni@redhat.com, sdf@fomichev.me, jdamato@fastly.com, netdev@vger.kernel.org Subject: [PATCH AUTOSEL 5.4 69/79] net-sysfs: prevent uncleared queues from being re-added Date: Mon, 5 May 2025 19:21:41 -0400 Message-Id: <20250505232151.2698893-69-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250505232151.2698893-1-sashal@kernel.org> References: <20250505232151.2698893-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.4.293 Content-Transfer-Encoding: 8bit From: Antoine Tenart [ Upstream commit 7e54f85c60828842be27e0149f3533357225090e ] With the (upcoming) removal of the rtnl_trylock/restart_syscall logic and because of how Tx/Rx queues are implemented (and their requirements), it might happen that a queue is re-added before having the chance to be cleared. In such rare case, do not complete the queue addition operation. Signed-off-by: Antoine Tenart Link: https://patch.msgid.link/20250204170314.146022-4-atenart@kernel.org Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/core/net-sysfs.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index bcad7028bbf45..6b0c682e5ea70 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -968,6 +968,22 @@ static int rx_queue_add_kobject(struct net_device *dev, int index) struct kobject *kobj = &queue->kobj; int error = 0; + /* Rx queues are cleared in rx_queue_release to allow later + * re-registration. This is triggered when their kobj refcount is + * dropped. + * + * If a queue is removed while both a read (or write) operation and a + * the re-addition of the same queue are pending (waiting on rntl_lock) + * it might happen that the re-addition will execute before the read, + * making the initial removal to never happen (queue's kobj refcount + * won't drop enough because of the pending read). In such rare case, + * return to allow the removal operation to complete. + */ + if (unlikely(kobj->state_initialized)) { + netdev_warn_once(dev, "Cannot re-add rx queues before their removal completed"); + return -EAGAIN; + } + /* Kobject_put later will trigger rx_queue_release call which * decreases dev refcount: Take that reference here */ @@ -1558,6 +1574,22 @@ static int netdev_queue_add_kobject(struct net_device *dev, int index) struct kobject *kobj = &queue->kobj; int error = 0; + /* Tx queues are cleared in netdev_queue_release to allow later + * re-registration. This is triggered when their kobj refcount is + * dropped. + * + * If a queue is removed while both a read (or write) operation and a + * the re-addition of the same queue are pending (waiting on rntl_lock) + * it might happen that the re-addition will execute before the read, + * making the initial removal to never happen (queue's kobj refcount + * won't drop enough because of the pending read). In such rare case, + * return to allow the removal operation to complete. + */ + if (unlikely(kobj->state_initialized)) { + netdev_warn_once(dev, "Cannot re-add tx queues before their removal completed"); + return -EAGAIN; + } + /* Kobject_put later will trigger netdev_queue_release call * which decreases dev refcount: Take that reference here */ -- 2.39.5