netdev - Re: [PATCH v12 10/26] nvme-tcp: Deal with netdevice DOWN events

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Message-ID: <186675e2-464f-bec4-1a26-5a516ef11540@grimberg.me>
Date: Wed, 16 Aug 2023 17:10:39 +0300
From: Sagi Grimberg <sagi@...mberg.me>
To: Aurelien Aptel <aaptel@...dia.com>, linux-nvme@...ts.infradead.org,
 netdev@...r.kernel.org, hch@....de, kbusch@...nel.org, axboe@...com,
 chaitanyak@...dia.com, davem@...emloft.net, kuba@...nel.org
Cc: Or Gerlitz <ogerlitz@...dia.com>, aurelien.aptel@...il.com,
 smalin@...dia.com, malin1024@...il.com, yorayz@...dia.com,
 borisp@...dia.com, galshalom@...dia.com, mgurtovoy@...dia.com
Subject: Re: [PATCH v12 10/26] nvme-tcp: Deal with netdevice DOWN events


>>> +     switch (event) {
>>> +     case NETDEV_GOING_DOWN:
>>> +             mutex_lock(&nvme_tcp_ctrl_mutex);
>>> +             list_for_each_entry(ctrl, &nvme_tcp_ctrl_list, list) {
>>> +                     if (ndev == ctrl->offloading_netdev)
>>> +                             nvme_tcp_error_recovery(&ctrl->ctrl);
>>> +             }
>>> +             mutex_unlock(&nvme_tcp_ctrl_mutex);
>>> +             flush_workqueue(nvme_reset_wq);
>>
>> In what context is this called? because every time we flush a workqueue,
>> lockdep finds another reason to complain about something...
> 
> Thanks for highlighting this, we re-checked it and we found that we are
> covered by nvme_tcp_error_recovery(), we can remove the
> flush_workqueue() call above.

Don't you need to flush at least err_work? How do you know that it
completed and put all the references?