linux-kernel - [PATCH v3 10/14] wifi: mac80211: Remove redundant rcu_read_lock/unlock() in spin

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20250916044735.2316171-11-dolinux.peng@gmail.com>
Date: Tue, 16 Sep 2025 12:47:31 +0800
From: pengdonglin <dolinux.peng@...il.com>
To: tj@...nel.org,
	tony.luck@...el.com,
	jani.nikula@...ux.intel.com,
	ap420073@...il.com,
	jv@...sburgh.net,
	freude@...ux.ibm.com,
	bcrl@...ck.org,
	trondmy@...nel.org,
	longman@...hat.com,
	kees@...nel.org
Cc: bigeasy@...utronix.de,
	hdanton@...a.com,
	paulmck@...nel.org,
	linux-kernel@...r.kernel.org,
	linux-rt-devel@...ts.linux.dev,
	linux-nfs@...r.kernel.org,
	linux-aio@...ck.org,
	linux-fsdevel@...r.kernel.org,
	linux-security-module@...r.kernel.org,
	netdev@...r.kernel.org,
	intel-gfx@...ts.freedesktop.org,
	linux-wireless@...r.kernel.org,
	linux-acpi@...r.kernel.org,
	linux-s390@...r.kernel.org,
	cgroups@...r.kernel.org,
	pengdonglin <dolinux.peng@...il.com>,
	Johannes Berg <johannes@...solutions.net>,
	pengdonglin <pengdonglin@...omi.com>
Subject: [PATCH v3 10/14] wifi: mac80211: Remove redundant rcu_read_lock/unlock() in spin_lock

From: pengdonglin <pengdonglin@...omi.com>

Since commit a8bb74acd8efe ("rcu: Consolidate RCU-sched update-side function definitions")
there is no difference between rcu_read_lock(), rcu_read_lock_bh() and
rcu_read_lock_sched() in terms of RCU read section and the relevant grace
period. That means that spin_lock(), which implies rcu_read_lock_sched(),
also implies rcu_read_lock().

There is no need no explicitly start a RCU read section if one has already
been started implicitly by spin_lock().

Simplify the code and remove the inner rcu_read_lock() invocation.

Cc: Johannes Berg <johannes@...solutions.net>
Signed-off-by: pengdonglin <pengdonglin@...omi.com>
Signed-off-by: pengdonglin <dolinux.peng@...il.com>
---
 net/mac80211/cfg.c            | 2 --
 net/mac80211/debugfs.c        | 2 --
 net/mac80211/debugfs_netdev.c | 2 --
 net/mac80211/debugfs_sta.c    | 2 --
 net/mac80211/sta_info.c       | 2 --
 5 files changed, 10 deletions(-)

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 2ed07fa121ab..4fe50d4c461d 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -4825,7 +4825,6 @@ static int ieee80211_get_txq_stats(struct wiphy *wiphy,
 	int ret = 0;
 
 	spin_lock_bh(&local->fq.lock);
-	rcu_read_lock();
 
 	if (wdev) {
 		sdata = IEEE80211_WDEV_TO_SUB_IF(wdev);
@@ -4851,7 +4850,6 @@ static int ieee80211_get_txq_stats(struct wiphy *wiphy,
 	}
 
 out:
-	rcu_read_unlock();
 	spin_unlock_bh(&local->fq.lock);
 
 	return ret;
diff --git a/net/mac80211/debugfs.c b/net/mac80211/debugfs.c
index e8b78ec682da..82099f4cedbe 100644
--- a/net/mac80211/debugfs.c
+++ b/net/mac80211/debugfs.c
@@ -82,7 +82,6 @@ static ssize_t aqm_read(struct file *file,
 	int len = 0;
 
 	spin_lock_bh(&local->fq.lock);
-	rcu_read_lock();
 
 	len = scnprintf(buf, sizeof(buf),
 			"access name value\n"
@@ -105,7 +104,6 @@ static ssize_t aqm_read(struct file *file,
 			fq->limit,
 			fq->quantum);
 
-	rcu_read_unlock();
 	spin_unlock_bh(&local->fq.lock);
 
 	return simple_read_from_buffer(user_buf, count, ppos,
diff --git a/net/mac80211/debugfs_netdev.c b/net/mac80211/debugfs_netdev.c
index 1dac78271045..30a5a978a678 100644
--- a/net/mac80211/debugfs_netdev.c
+++ b/net/mac80211/debugfs_netdev.c
@@ -625,7 +625,6 @@ static ssize_t ieee80211_if_fmt_aqm(
 	txqi = to_txq_info(sdata->vif.txq);
 
 	spin_lock_bh(&local->fq.lock);
-	rcu_read_lock();
 
 	len = scnprintf(buf,
 			buflen,
@@ -642,7 +641,6 @@ static ssize_t ieee80211_if_fmt_aqm(
 			txqi->tin.tx_bytes,
 			txqi->tin.tx_packets);
 
-	rcu_read_unlock();
 	spin_unlock_bh(&local->fq.lock);
 
 	return len;
diff --git a/net/mac80211/debugfs_sta.c b/net/mac80211/debugfs_sta.c
index 49061bd4151b..ef75255d47d5 100644
--- a/net/mac80211/debugfs_sta.c
+++ b/net/mac80211/debugfs_sta.c
@@ -148,7 +148,6 @@ static ssize_t sta_aqm_read(struct file *file, char __user *userbuf,
 		return -ENOMEM;
 
 	spin_lock_bh(&local->fq.lock);
-	rcu_read_lock();
 
 	p += scnprintf(p,
 		       bufsz + buf - p,
@@ -178,7 +177,6 @@ static ssize_t sta_aqm_read(struct file *file, char __user *userbuf,
 			       test_bit(IEEE80211_TXQ_DIRTY, &txqi->flags) ? " DIRTY" : "");
 	}
 
-	rcu_read_unlock();
 	spin_unlock_bh(&local->fq.lock);
 
 	rv = simple_read_from_buffer(userbuf, count, ppos, buf, p - buf);
diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index 8c550aab9bdc..663318a75d7f 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -2637,13 +2637,11 @@ static void sta_set_tidstats(struct sta_info *sta,
 
 	if (link_id < 0 && tid < IEEE80211_NUM_TIDS) {
 		spin_lock_bh(&local->fq.lock);
-		rcu_read_lock();
 
 		tidstats->filled |= BIT(NL80211_TID_STATS_TXQ_STATS);
 		ieee80211_fill_txq_stats(&tidstats->txq_stats,
 					 to_txq_info(sta->sta.txq[tid]));
 
-		rcu_read_unlock();
 		spin_unlock_bh(&local->fq.lock);
 	}
 }
-- 
2.34.1