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 6AC772D5D1E; Mon, 5 May 2025 22:54:56 +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=1746485696; cv=none; b=gf6MVBeaAhSiM87QCK2Nbf962Z84zEzmo3Krvn+4DP0LzuSroo7USPWiZr6vxTL6hIC+caivQLKkKom9esNaX0Lr15nbmsrvBivdz0jVMjnyFuDCqZJmeS4TuvQsfLTBuMwPGZO+MoCUf5AdVP3L98doDdqxxsnOZW34XAVRn4k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746485696; c=relaxed/simple; bh=PToc3oAucTTxUmNd2oG82d8nn7vf2GxBtLFvdRfeVBQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=CrwUnaf1u5bIFLvjzzCAnB1i9iX2tc3rogkIWOW8CXOro8A8KX2wqNuT+q35u+jy0TlL5BUJcPrOnEunTaO4N5omvN6D6ZW0OwVJOJnQhtH6DNklfGuGM1iuiQAtJTSAxoPQGiOrYmZhYjsOkPDC6+eApZiX3Nr9txqcil1AdTU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JCK05MEa; 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="JCK05MEa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F406EC4CEE4; Mon, 5 May 2025 22:54:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746485696; bh=PToc3oAucTTxUmNd2oG82d8nn7vf2GxBtLFvdRfeVBQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JCK05MEaw03ri7xDluWDUKGpm9AM/ZTjhwGHI7VGN++vspHmzKjysV9XkaRntoiKn vH9NW6p1tV/EPv5bFMZqUhOq9vsoVyAuthSmtn7iMbhWtFGKMr/wKwjpVZ4ellvmTl QAwOoI3DH2BT9jsnrt2wCDnxr2OeeXbo4xQTJ9tjTkBfHSOU2Nw2OlDlx2bOhQhJ4D m8vVfSau240OLgFtGC4rIivlhIS2cqIxK0E37MEVSbjY10B8OTSs1xf6GnxtGo2z8e TPdx7U/eOXHSHu/eLQqvA37c0dzg/KEqLsYFWDvWdLhRwSwHHYLUireANRyRkbWw9A aqEzi2ai9dsFg== 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, aleksander.lobakin@intel.com, netdev@vger.kernel.org Subject: [PATCH AUTOSEL 6.12 430/486] net-sysfs: prevent uncleared queues from being re-added Date: Mon, 5 May 2025 18:38:26 -0400 Message-Id: <20250505223922.2682012-430-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250505223922.2682012-1-sashal@kernel.org> References: <20250505223922.2682012-1-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 6.12.26 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 b398a2e0c243d..d6d0c3082b82b 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -1100,6 +1100,22 @@ 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 */ @@ -1811,6 +1827,22 @@ 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