Received-SPF: pass (google.com: domain of linux-wireless-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <26e9ae91-8e13-df45-815c-cb45c1911032@nbd.name>
Date:   Thu, 15 Sep 2022 18:18:39 +0200
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0)
 Gecko/20100101 Thunderbird/91.13.0
Subject: Re: [PATCH] mac80211: Ensure vif queues are operational after start
Content-Language: en-US
To:     Alexander Wetzel <alexander@wetzel-home.de>,
        linux-wireless@vger.kernel.org
Cc:     Johannes Berg <johannes@sipsolutions.net>
References: <20220915130946.302803-1-alexander@wetzel-home.de>
From:   Felix Fietkau <nbd@nbd.name>
In-Reply-To: <20220915130946.302803-1-alexander@wetzel-home.de>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk


On 15.09.22 15:09, Alexander Wetzel wrote:
> Make sure local->queue_stop_reasons and vif.txqs_stopped stay in sync.
> 
> When a new vif is created the queues may end up in an inconsistent state
> and be inoperable:
> Communication not using iTXQ will work, allowing to e.g. complete the
> association. But the 4-way handshake will time out. The sta will not
> send out any skbs queued in iTXQs.
> 
> All normal attempts to start the queues will fail when reaching this
> state.
> local->queue_stop_reasons will have marked all queues as operational but
> vif.txqs_stopped will still be set, creating an inconsistent internal
> state.
> 
> In reality this seems to be race between the mac80211 function
> ieee80211_do_open() setting SDATA_STATE_RUNNING and the wake_txqs_tasklet:
> Depending on the driver and the timing the queues may end up to be
> operational or not.
> 
> Cc: stable@vger.kernel.org
> Fixes: f856373e2f31 ("wifi: mac80211: do not wake queues on a vif that is being stopped")
> Signed-off-by: Alexander Wetzel <alexander@wetzel-home.de>

Acked-by: Felix Fietkau <nbd@nbd.name>

Thanks for figuring this one out,

- Felix