linux-kernel - Re: [PATCH AUTOSEL 5.4 06/16] wifi: mac80211: do not wake queues on a vif that is being stopped

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Date:   Tue, 19 Jul 2022 18:58:34 -0700
From:   Ben Greear <greearb@...delatech.com>
To:     Sasha Levin <sashal@...nel.org>, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Cc:     Felix Fietkau <nbd@....name>,
        Toke Høiland-Jørgensen <toke@...nel.org>,
        Johannes Berg <johannes.berg@...el.com>,
        johannes@...solutions.net, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH AUTOSEL 5.4 06/16] wifi: mac80211: do not wake queues on a
 vif that is being stopped

I think this one had a regression and needs another init-lock-early patch to keep from causing
problems?

It certainly broke my 5.17-ish kernel...

Thanks,
Ben

On 7/19/22 6:17 PM, Sasha Levin wrote:
> From: Felix Fietkau <nbd@....name>
> 
> [ Upstream commit f856373e2f31ffd340e47e2b00027bd4070f74b3 ]
> 
> When a vif is being removed and sdata->bss is cleared, __ieee80211_wake_txqs
> can still be called on it, which crashes as soon as sdata->bss is being
> dereferenced.
> To fix this properly, check for SDATA_STATE_RUNNING before waking queues,
> and take the fq lock when setting it (to ensure that __ieee80211_wake_txqs
> observes the change when running on a different CPU)
> 
> Signed-off-by: Felix Fietkau <nbd@....name>
> Acked-by: Toke Høiland-Jørgensen <toke@...nel.org>
> Link: https://lore.kernel.org/r/20220531190824.60019-1-nbd@nbd.name
> Signed-off-by: Johannes Berg <johannes.berg@...el.com>
> Signed-off-by: Sasha Levin <sashal@...nel.org>
> ---
>   net/mac80211/iface.c | 2 ++
>   net/mac80211/util.c  | 3 +++
>   2 files changed, 5 insertions(+)
> 
> diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
> index ddc001ad9055..48bda8aaa90a 100644
> --- a/net/mac80211/iface.c
> +++ b/net/mac80211/iface.c
> @@ -803,7 +803,9 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata,
>   	bool cancel_scan;
>   	struct cfg80211_nan_func *func;
>   
> +	spin_lock_bh(&local->fq.lock);
>   	clear_bit(SDATA_STATE_RUNNING, &sdata->state);
> +	spin_unlock_bh(&local->fq.lock);
>   
>   	cancel_scan = rcu_access_pointer(local->scan_sdata) == sdata;
>   	if (cancel_scan)
> diff --git a/net/mac80211/util.c b/net/mac80211/util.c
> index c1c117fdf318..8ae0186091b6 100644
> --- a/net/mac80211/util.c
> +++ b/net/mac80211/util.c
> @@ -250,6 +250,9 @@ static void __ieee80211_wake_txqs(struct ieee80211_sub_if_data *sdata, int ac)
>   	local_bh_disable();
>   	spin_lock(&fq->lock);
>   
> +	if (!test_bit(SDATA_STATE_RUNNING, &sdata->state))
> +		goto out;
> +
>   	if (sdata->vif.type == NL80211_IFTYPE_AP)
>   		ps = &sdata->bss->ps;
>   
> 


-- 
Ben Greear <greearb@...delatech.com>
Candela Technologies Inc  http://www.candelatech.com