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 855E28BE5 for ; Mon, 19 Jun 2023 10:49:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F3ECBC433C0; Mon, 19 Jun 2023 10:49:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1687171754; bh=u7arquJ/0Y8MYINl9rJwyGBTs/7zGRbhhdUlguKJA6o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tq8m+c/lvWZQOIoGW2qmLx2qcogp09J37gSLJR1h7ak8uj3fb3K8spbmZvV8W6j/Q lyF7qu13uZ67BkB9pWhgc99hllq9IhquTezLhUU7XodDHfDiBQ/ek/swWeQrzurUkj Wf/6f8FiK9dy+Fd2kY6JMA1+Ytp9vw6XAgh4LLZM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Mingshuai Ren , Vlad Buslov , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.1 145/166] net/sched: cls_api: Fix lockup on flushing explicitly created chain Date: Mon, 19 Jun 2023 12:30:22 +0200 Message-ID: <20230619102201.757409207@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230619102154.568541872@linuxfoundation.org> References: <20230619102154.568541872@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Vlad Buslov [ Upstream commit c9a82bec02c339cdda99b37c5e62b3b71fc4209c ] Mingshuai Ren reports: When a new chain is added by using tc, one soft lockup alarm will be generated after delete the prio 0 filter of the chain. To reproduce the problem, perform the following steps: (1) tc qdisc add dev eth0 root handle 1: htb default 1 (2) tc chain add dev eth0 (3) tc filter del dev eth0 chain 0 parent 1: prio 0 (4) tc filter add dev eth0 chain 0 parent 1: Fix the issue by accounting for additional reference to chains that are explicitly created by RTM_NEWCHAIN message as opposed to implicitly by RTM_NEWTFILTER message. Fixes: 726d061286ce ("net: sched: prevent insertion of new classifiers during chain flush") Reported-by: Mingshuai Ren Closes: https://lore.kernel.org/lkml/87legswvi3.fsf@nvidia.com/T/ Signed-off-by: Vlad Buslov Link: https://lore.kernel.org/r/20230612093426.2867183-1-vladbu@nvidia.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/sched/cls_api.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c index 0dbfc37d97991..445ab1b0537da 100644 --- a/net/sched/cls_api.c +++ b/net/sched/cls_api.c @@ -552,8 +552,8 @@ static void __tcf_chain_put(struct tcf_chain *chain, bool by_act, { struct tcf_block *block = chain->block; const struct tcf_proto_ops *tmplt_ops; + unsigned int refcnt, non_act_refcnt; bool free_block = false; - unsigned int refcnt; void *tmplt_priv; mutex_lock(&block->lock); @@ -573,13 +573,15 @@ static void __tcf_chain_put(struct tcf_chain *chain, bool by_act, * save these to temporary variables. */ refcnt = --chain->refcnt; + non_act_refcnt = refcnt - chain->action_refcnt; tmplt_ops = chain->tmplt_ops; tmplt_priv = chain->tmplt_priv; - /* The last dropped non-action reference will trigger notification. */ - if (refcnt - chain->action_refcnt == 0 && !by_act) { - tc_chain_notify_delete(tmplt_ops, tmplt_priv, chain->index, - block, NULL, 0, 0, false); + if (non_act_refcnt == chain->explicitly_created && !by_act) { + if (non_act_refcnt == 0) + tc_chain_notify_delete(tmplt_ops, tmplt_priv, + chain->index, block, NULL, 0, 0, + false); /* Last reference to chain, no need to lock. */ chain->flushing = false; } -- 2.39.2