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 6E28D22DA0B; Mon, 5 May 2025 23:05:25 +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=1746486326; cv=none; b=JNWZYak7Hql2B96qvcP+w3up6AAWOhjcojIpNHBxzvIRCvsMVy1ESLKGXi1xv2O4p8eGQOo+qk4JzAmB8bKPOkni7FaTtFVviODWzw+JF4pB+Y4zfnfZmK9iwUCxSeqxO8Mp/M5hykZGgG5CvuzUrPylUJSZ0dEdhaa/4EZcl6E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746486326; c=relaxed/simple; bh=FuUTa7qeVl1tru7h7FAYg3CCm3SlmL2bCM5XtGtIPQQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=hlRLeS8Al9NJPG2q9JV+MIpNclIRzS++Q453KQ29KS8wFfJW6cGH7QJ6GTyTkXN1LTiYS3Jp2VEcztZ4cHf3n1AGEKK1gPsBERi+e8bzP+yl9frqJsYFp5uDVffdXiHcvDPG7601tSaqlYQiMErF0DlTSvwZE18+Z8ginYc6H2c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GjFS5akl; 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="GjFS5akl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1F6C1C4CEE4; Mon, 5 May 2025 23:05:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746486325; bh=FuUTa7qeVl1tru7h7FAYg3CCm3SlmL2bCM5XtGtIPQQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GjFS5aklkvsFLhvVln81hkvg++Q8lJNcgHZ/17vcYgimZzNNwDF6hen9mcXdjkoAx 4gP6/d/yYvgwOVVvrTeriAWF+Y13bsUruLR1/eO1AHNWbC9hsHih0Zd+VBQTI8Dr/V VIxCxXTJeF5mZ1+e7B/cbpwuQQHD3v6KeTcuYTTOrEW0Wh6rCiDkC0mEqrMqkdiTSO EvVK6Obb/QKQrcpta4mZ76cvkpqbOYjUvc99ys72lRiJetw01wuoND137Wrb0HQoj4 eszMJZ4p+PuXd8jgOY27p4evdDg+lzl10jgUOAEoD1cWWZv6VrbnyLsyfPq2W1zmPM LhstnfNwvS2lw== 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 6.6 260/294] net-sysfs: prevent uncleared queues from being re-added Date: Mon, 5 May 2025 18:56:00 -0400 Message-Id: <20250505225634.2688578-260-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250505225634.2688578-1-sashal@kernel.org> References: <20250505225634.2688578-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.6.89 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 f7404bc679746..d88682ae0e126 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -1077,6 +1077,22 @@ 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 */ @@ -1684,6 +1700,22 @@ 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