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From:   Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= <toke@kernel.org>
To:     Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
        Johannes Berg <johannes@sipsolutions.net>,
        Felix Fietkau <nbd@nbd.name>
Cc:     linux-wireless@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [PATCH v2] wifi: mac80211: do not abuse fq.lock in
 ieee80211_do_stop()
In-Reply-To: <9cc9b81d-75a3-3925-b612-9d0ad3cab82b@I-love.SAKURA.ne.jp>
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 <81f3eeda-0888-2869-659e-dc38c0a9debf@I-love.SAKURA.ne.jp>
 <9cc9b81d-75a3-3925-b612-9d0ad3cab82b@I-love.SAKURA.ne.jp>
Date:   Mon, 18 Jul 2022 13:22:22 +0200
Message-ID: <874jzemzrl.fsf@toke.dk>
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Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> writes:

> lockdep complains use of uninitialized spinlock at ieee80211_do_stop() [1=
],
> for commit f856373e2f31ffd3 ("wifi: mac80211: do not wake queues on a vif
> that is being stopped") guards clear_bit() using fq.lock even before
> fq_init() from ieee80211_txq_setup_flows() initializes this spinlock.
>
> According to discussion [2], Toke was not happy with expanding usage of
> fq.lock. Since __ieee80211_wake_txqs() is called under RCU read lock, we
> can instead use synchronize_rcu() for flushing ieee80211_wake_txqs().

Ah, that's a neat solution! :)

Acked-by: Toke H=C3=B8iland-J=C3=B8rgensen <toke@kernel.org>