linux-kernel - [PATCH] cfg80211: Pass lockdep expression to RCU lists

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Message-Id: <20200219091102.10709-1-frextrite@gmail.com>
Date:   Wed, 19 Feb 2020 14:41:04 +0530
From:   Amol Grover <frextrite@...il.com>
To:     Johannes Berg <johannes@...solutions.net>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        Joel Fernandes <joel@...lfernandes.org>,
        Madhuparna Bhowmik <madhuparnabhowmik10@...il.com>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Amol Grover <frextrite@...il.com>
Subject: [PATCH] cfg80211: Pass lockdep expression to RCU lists

rdev->sched_scan_req_list maybe traversed using list_for_each_entry_rcu
outside an RCU read-side critical section but under the protection
of rtnl_mutex.

Hence, add corresponding lockdep expression to silence false-positive
warnings, and harden RCU lists.

Signed-off-by: Amol Grover <frextrite@...il.com>
---
 net/wireless/scan.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index aef240fdf8df..7f1af8f347b1 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -556,9 +556,8 @@ cfg80211_find_sched_scan_req(struct cfg80211_registered_device *rdev, u64 reqid)
 {
 	struct cfg80211_sched_scan_request *pos;
 
-	WARN_ON_ONCE(!rcu_read_lock_held() && !lockdep_rtnl_is_held());
-
-	list_for_each_entry_rcu(pos, &rdev->sched_scan_req_list, list) {
+	list_for_each_entry_rcu(pos, &rdev->sched_scan_req_list, list,
+				lockdep_rtnl_is_held()) {
 		if (pos->reqid == reqid)
 			return pos;
 	}
-- 
2.24.1