linux-kernel - [PATCH 6.1.y 1/2] wifi: mac80211: avoid lockdep checking when removing deflink

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Message-ID: <20250823202208.43086-1-hannelotta@gmail.com>
Date: Sat, 23 Aug 2025 23:22:07 +0300
From: Hanne-Lotta Mäenpää <hannelotta@...il.com>
To: stable@...r.kernel.org
Cc: johannes@...solutions.net,
	shaul.triebitz@...el.com,
	linux-wireless@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-kernel-mentees@...ts.linux.dev,
	skhan@...uxfoundation.org,
	david.hunter.linux@...il.com,
	Benjamin Berg <benjamin.berg@...el.com>,
	Gregory Greenman <gregory.greenman@...el.com>,
	Johannes Berg <johannes.berg@...el.com>,
	Hanne-Lotta Mäenpää <hannelotta@...il.com>
Subject: [PATCH 6.1.y 1/2] wifi: mac80211: avoid lockdep checking when removing deflink

From: Benjamin Berg <benjamin.berg@...el.com>

struct sta_info may be removed without holding sta_mtx if it has not
yet been inserted. To support this, only assert that the lock is held
for links other than the deflink.

This fixes lockdep issues that may be triggered in error cases.

Signed-off-by: Benjamin Berg <benjamin.berg@...el.com>
Signed-off-by: Gregory Greenman <gregory.greenman@...el.com>
Link: https://lore.kernel.org/r/20230619161906.cdd81377dea0.If5a6734b4b85608a2275a09b4f99b5564d82997f@changeid
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
(cherry picked from commit b8b80770b26c4591f20f1cde3328e5f1489c4488)
Signed-off-by: Hanne-Lotta Mäenpää <hannelotta@...il.com>
---
 net/mac80211/sta_info.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index dd1864f6549f..e9ae92094794 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -357,8 +357,9 @@ static void sta_remove_link(struct sta_info *sta, unsigned int link_id,
 	struct sta_link_alloc *alloc = NULL;
 	struct link_sta_info *link_sta;
 
-	link_sta = rcu_dereference_protected(sta->link[link_id],
-					     lockdep_is_held(&sta->local->sta_mtx));
+	link_sta = rcu_access_pointer(sta->link[link_id]);
+	if (link_sta != &sta->deflink)
+		lockdep_assert_held(&sta->local->sta_mtx);
 
 	if (WARN_ON(!link_sta))
 		return;
-- 
2.50.0