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

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Message-ID: <87fracop8k.fsf@toke.dk>
Date: Mon, 17 Nov 2025 12:47:07 +0100
From: Toke Høiland-Jørgensen <toke@...e.dk>
To: pengdonglin <dolinux.peng@...il.com>, 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>, Jakub Kicinski <kuba@...nel.org>, pengdonglin
 <pengdonglin@...omi.com>
Subject: Re: [PATCH v3 14/14] wifi: ath9k: Remove redundant
 rcu_read_lock/unlock() in spin_lock

pengdonglin <dolinux.peng@...il.com> writes:

> 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>

Acked-by: Toke Høiland-Jørgensen <toke@...e.dk>