linux-kernel - [PATCH v3 14/14] wifi: ath9k: Remove redundant rcu_read_lock/unlock() in spin

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Message-Id: <20250916044735.2316171-15-dolinux.peng@gmail.com>
Date: Tue, 16 Sep 2025 12:47:35 +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,
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	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>,
	"Toke" <toke@...e.dk>,
	Jakub Kicinski <kuba@...nel.org>,
	pengdonglin <pengdonglin@...omi.com>
Subject: [PATCH v3 14/14] wifi: ath9k: 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: "Toke" <toke@...e.dk>
Cc: Jakub Kicinski <kuba@...nel.org>
Signed-off-by: pengdonglin <pengdonglin@...omi.com>
Signed-off-by: pengdonglin <dolinux.peng@...il.com>
---
 drivers/net/wireless/ath/ath9k/xmit.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c
index 0ac9212e42f7..4a0f465aa2fe 100644
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -1993,7 +1993,6 @@ void ath_txq_schedule(struct ath_softc *sc, struct ath_txq *txq)
 
 	ieee80211_txq_schedule_start(hw, txq->mac80211_qnum);
 	spin_lock_bh(&sc->chan_lock);
-	rcu_read_lock();
 
 	if (sc->cur_chan->stopped)
 		goto out;
@@ -2011,7 +2010,6 @@ void ath_txq_schedule(struct ath_softc *sc, struct ath_txq *txq)
 	}
 
 out:
-	rcu_read_unlock();
 	spin_unlock_bh(&sc->chan_lock);
 	ieee80211_txq_schedule_end(hw, txq->mac80211_qnum);
 }
-- 
2.34.1