This is a note to let you know that I've just added the patch titled
net/sched: cls_api: Fix lockup on flushing explicitly created chain
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-sched-cls_api-fix-lockup-on-flushing-explicitly-.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 3ec77e9521f9d3f4d4e19e89f2cf21f103cb9f66
Author: Vlad Buslov <vladbu@xxxxxxxxxx>
Date: Mon Jun 12 11:34:26 2023 +0200
net/sched: cls_api: Fix lockup on flushing explicitly created chain
[ 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 <renmingshuai@xxxxxxxxxx>
Closes: https://lore.kernel.org/lkml/87legswvi3.fsf@xxxxxxxxxx/T/
Signed-off-by: Vlad Buslov <vladbu@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230612093426.2867183-1-vladbu@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index befe42aad04ba..beedd0d2b5097 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -533,8 +533,8 @@ 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);
@@ -554,13 +554,15 @@ 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;
}
