From 0b0e2ff10356e7e2ffd66ecdd6eee69a2f03449b Mon Sep 17 00:00:00 2001 From: Vladimir Oltean Date: Mon, 28 Feb 2022 16:17:15 +0200 Subject: net: dsa: restore error path of dsa_tree_change_tag_proto When the DSA_NOTIFIER_TAG_PROTO returns an error, the user space process which initiated the protocol change exits the kernel processing while still holding the rtnl_mutex. So any other process attempting to lock the rtnl_mutex would deadlock after such event. The error handling of DSA_NOTIFIER_TAG_PROTO was inadvertently changed by the blamed commit, introducing this regression. We must still call rtnl_unlock(), and we must still call DSA_NOTIFIER_TAG_PROTO for the old protocol. The latter is due to the limiting design of notifier chains for cross-chip operations, which don't have a built-in error recovery mechanism - we should look into using notifier_call_chain_robust for that. Fixes: dc452a471dba ("net: dsa: introduce tagger-owned storage for private and shared data") Signed-off-by: Vladimir Oltean Link: https://lore.kernel.org/r/20220228141715.146485-1-vladimir.oltean@nxp.com Signed-off-by: Jakub Kicinski --- net/dsa/dsa2.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/dsa/dsa2.c') diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c index dcad3100b164..209496996cdf 100644 --- a/net/dsa/dsa2.c +++ b/net/dsa/dsa2.c @@ -1261,7 +1261,7 @@ int dsa_tree_change_tag_proto(struct dsa_switch_tree *dst, info.tag_ops = tag_ops; err = dsa_tree_notify(dst, DSA_NOTIFIER_TAG_PROTO, &info); if (err) - return err; + goto out_unlock; err = dsa_tree_bind_tag_proto(dst, tag_ops); if (err) -- cgit v1.2.3-58-ga151 From e1bec7fa1cee311a6d3fb9161037c7675904134d Mon Sep 17 00:00:00 2001 From: Vladimir Oltean Date: Thu, 3 Mar 2022 17:42:49 +0200 Subject: net: dsa: make dsa_tree_change_tag_proto actually unwind the tag proto change The blamed commit said one thing but did another. It explains that we should restore the "return err" to the original "goto out_unwind_tagger", but instead it replaced it with "goto out_unlock". When DSA_NOTIFIER_TAG_PROTO fails after the first switch of a multi-switch tree, the switches would end up not using the same tagging protocol. Fixes: 0b0e2ff10356 ("net: dsa: restore error path of dsa_tree_change_tag_proto") Signed-off-by: Vladimir Oltean Link: https://lore.kernel.org/r/20220303154249.1854436-1-vladimir.oltean@nxp.com Signed-off-by: Jakub Kicinski --- net/dsa/dsa2.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/dsa/dsa2.c') diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c index 209496996cdf..b4e67758e104 100644 --- a/net/dsa/dsa2.c +++ b/net/dsa/dsa2.c @@ -1261,7 +1261,7 @@ int dsa_tree_change_tag_proto(struct dsa_switch_tree *dst, info.tag_ops = tag_ops; err = dsa_tree_notify(dst, DSA_NOTIFIER_TAG_PROTO, &info); if (err) - goto out_unlock; + goto out_unwind_tagger; err = dsa_tree_bind_tag_proto(dst, tag_ops); if (err) -- cgit v1.2.3-58-ga151