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 CC65F2F1CCD; Mon, 5 May 2025 23:12:41 +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=1746486762; cv=none; b=Yq1nVPFUaQMmAEGA0tNNK9NY/kFGtw1T4/AEUQYmWxgOl6tNDX0YSL8AbZKQMfe6BP2c5K7pT85Q1vDbk+AROt8CBa9tfxOcqoFOwXNTSMclNeC0YiMP/NGGIiWGGHTeWezfobSmuln0mesh3TkWl7NoB4cBPSd18eXG3VLNkrI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746486762; c=relaxed/simple; bh=br+Mbv3A/bYJ0vyPTdvaWCJwXmFes9Pkihotvm54Mdc=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=NaSP21wJXcLmdS45+KF7Njm4zR6gHqdugURd+gsupMh3WU5NMFMv93jZNISuBAjL/4R0DvST/rEAyJUQyGcugUnHfkvPBZ2pyObDAMRyK39cxyVNhkadlCIIR+KxzCmtjLGi0lgHu/osfFrhzbhbtAF46SS5AwhhoakcNBJlSNA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UsTovTg3; 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="UsTovTg3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 869D3C4CEED; Mon, 5 May 2025 23:12:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746486761; bh=br+Mbv3A/bYJ0vyPTdvaWCJwXmFes9Pkihotvm54Mdc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UsTovTg3WYA/As4Ma4nKgHMgIBljLkJ0tI8KxYORhZ4O1Y+t/bd6i6+rJmPJ6OY0Q x7MVS8Utr90/pPKcnCf1L4vQ7Q8Db2tLacUcYg7uIrPDlffE7YrnB1uHmil5J36ccb yvIBx5VlEMEpX0BGqzNN3SFKgqPM4Y3POEkYAejq3+GcQmj+0goJOMDUxAk3Ha2Nv6 d1Ta3a+ArdCccY8W1sfxkNhg61usEn3HmR00TTdfqCcHmnbMS+hL+86Vj1AX8LtT7M oYJudGkRxMi1QHsfsyJRJwd1MxbWSOYTQFT3m8EfFGBY/bYbRCr1dZQ9IvOFk9HJWC Ke4ZUwYhI2zcA== 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 6.1 189/212] net-sysfs: prevent uncleared queues from being re-added Date: Mon, 5 May 2025 19:06:01 -0400 Message-Id: <20250505230624.2692522-189-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250505230624.2692522-1-sashal@kernel.org> References: <20250505230624.2692522-1-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 6.1.136 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 8a06f97320e04..08d926cdd5804 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -1052,6 +1052,22 @@ 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 */ @@ -1655,6 +1671,22 @@ 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