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Subject: Re: [PATCH v2] wifi: mac80211: do not abuse fq.lock in
 ieee80211_do_stop()
From:   Kalle Valo <kvalo@kernel.org>
In-Reply-To: <9cc9b81d-75a3-3925-b612-9d0ad3cab82b@I-love.SAKURA.ne.jp>
References: <9cc9b81d-75a3-3925-b612-9d0ad3cab82b@I-love.SAKURA.ne.jp>
To:     Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc:     Johannes Berg <johannes@sipsolutions.net>,
        =?utf-8?q?Toke_H=C3=B8iland-J?= =?utf-8?q?=C3=B8rgensen?= 
        <toke@kernel.org>, Felix Fietkau <nbd@nbd.name>,
        linux-wireless@vger.kernel.org, netdev@vger.kernel.org
User-Agent: pwcli/0.1.1-git (https://github.com/kvalo/pwcli/) Python/3.7.3
Message-ID: <165814567948.32602.9899358496438464723.kvalo@kernel.org>
Date:   Mon, 18 Jul 2022 12:01:21 +0000 (UTC)
Precedence: bulk

Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> wrote:

> 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().
> 
> Link: https://syzkaller.appspot.com/bug?extid=eceab52db7c4b961e9d6 [1]
> Link: https://lkml.kernel.org/r/874k0zowh2.fsf@toke.dk [2]
> Reported-by: syzbot <syzbot+eceab52db7c4b961e9d6@syzkaller.appspotmail.com>
> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> Fixes: f856373e2f31ffd3 ("wifi: mac80211: do not wake queues on a vif that is being stopped")
> Tested-by: syzbot <syzbot+eceab52db7c4b961e9d6@syzkaller.appspotmail.com>
> Acked-by: Toke Høiland-Jørgensen <toke@kernel.org>

Patch applied to wireless-next.git, thanks.

3598cb6e1862 wifi: mac80211: do not abuse fq.lock in ieee80211_do_stop()

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/9cc9b81d-75a3-3925-b612-9d0ad3cab82b@I-love.SAKURA.ne.jp/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches