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authorVlad Buslov <vladbu@nvidia.com>2023-06-12 11:34:26 +0200
committerJakub Kicinski <kuba@kernel.org>2023-06-14 23:03:16 -0700
commitc9a82bec02c339cdda99b37c5e62b3b71fc4209c (patch)
tree8e4ba3b2f1cc67a3d71520cb605e01aa84fe6648 /net/sched/cls_api.c
parent24b454bc354ab7b1aa918a4fe3d7696516f592d4 (diff)
net/sched: cls_api: Fix lockup on flushing explicitly created chain
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@huawei.com> Closes: https://lore.kernel.org/lkml/87legswvi3.fsf@nvidia.com/T/ Signed-off-by: Vlad Buslov <vladbu@nvidia.com> Link: https://lore.kernel.org/r/20230612093426.2867183-1-vladbu@nvidia.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/sched/cls_api.c')
-rw-r--r--net/sched/cls_api.c12
1 files changed, 7 insertions, 5 deletions
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index c877a6343fd4..a193cc7b3241 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -657,8 +657,8 @@ 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);
@@ -678,13 +678,15 @@ 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;
}