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 68C19336169; Mon, 5 May 2025 22:36:35 +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=1746484595; cv=none; b=qE9maaDmhahgOXexHfrpkogJJgcWndBEPTNr4YWnLEcGqTEiW5XlEE7VfIk7LhxT55+lmcyXCItuqVItTgvdwcvy30nwwzryfMirDYyNl0/DPKsbMCD6NN7bezQV0PTvpln96cOHEiHdK9VlJHR2qIeJvPFgUnuMKodmPGPDvbg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746484595; c=relaxed/simple; bh=LuzbnwRZScN/e+C3yd0Up1cH7z0w2opPvPd0PfS1SFM=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=XiWdpGE9lp5OdfSeDC6WwEzdGXGmBc3Hz+LAS8YbAsv60ZOGNS07LOJOHEH/IzzYV1nBLKWah+VCj9MPTbTZRQlhaPAAZqoGkVMhWKY1j67pUFCpDjGuvY0DihwWO0F6DZI8Mylddd06Ym2nyQash1abMTAhkh5UR7dE+AcDPCg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=TzNfgGXy; 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="TzNfgGXy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1A81DC4CEE4; Mon, 5 May 2025 22:36:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746484595; bh=LuzbnwRZScN/e+C3yd0Up1cH7z0w2opPvPd0PfS1SFM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TzNfgGXynCkDN3AsdLZRY8DA9127DuqfW/s0AcatRp7Zi69Q9bjblrFuOFg/rpP4s 01zAkTk/d9rKBvWqzZXWvvUwrqNTkPp7k5Evl+105W2dkYMgjzRIhpa8CXa3j5uQwD UihkmOoWEAQe4JO2O1gJXWKmP+8UwaMgOtWwOfJib6J5JeHkz7XWnofV1FXG9ErC8/ toYj21Nh6z91CtbqKiXwMIpXhg2JTh3BYFFJekJnLqRsdihTXuv2vA5lCKwOIRoWdD 1BFiFlgRkFznItQW8Xa3elNR+nvutIxL1MPOzYGsDJHBfpDR2z2qPDhQ+/CSAj+yI6 U5crpxRCawzmA== 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 6.14 553/642] net-sysfs: prevent uncleared queues from being re-added Date: Mon, 5 May 2025 18:12:49 -0400 Message-Id: <20250505221419.2672473-553-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250505221419.2672473-1-sashal@kernel.org> References: <20250505221419.2672473-1-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 6.14.5 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 77465dc3cd648..87b2456aef08a 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -1131,6 +1131,22 @@ 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 */ @@ -1842,6 +1858,22 @@ 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