netdev - Re: [PATCH v2 net-next 00/23] net: add preliminary netdev refcount tracking

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Date:   Fri, 3 Dec 2021 16:47:43 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     "David S . Miller" <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>
Subject: Re: [PATCH v2 net-next 00/23] net: add preliminary netdev refcount
 tracking

On Thu,  2 Dec 2021 18:46:17 -0800 Eric Dumazet wrote:
> Two first patches add a generic infrastructure, that will be used
> to get tracking of refcount increments/decrements.
> 
> The general idea is to be able to precisely pair each decrement with
> a corresponding prior increment. Both share a cookie, basically
> a pointer to private data storing stack traces.
> 
> The third place adds dev_hold_track() and dev_put_track() helpers
> (CONFIG_NET_DEV_REFCNT_TRACKER)
> 
> Then a series of 20 patches converts some dev_hold()/dev_put()
> pairs to new hepers : dev_hold_track() and dev_put_track().
> 
> Hopefully this will be used by developpers and syzbot to
> root cause bugs that cause netdevice dismantles freezes.
> 
> With CONFIG_PCPU_DEV_REFCNT=n option, we were able to detect
> some class of bugs, but too late (when too many dev_put()
> were happening).

Hi Eric, there's a handful of kdoc warnings added here:

include/linux/netdevice.h:2278: warning: Function parameter or member 'refcnt_tracker' not described in 'net_device'
include/net/devlink.h:679: warning: Function parameter or member 'dev_tracker' not described in 'devlink_trap_metadata'
include/linux/netdevice.h:2283: warning: Function parameter or member 'refcnt_tracker' not described in 'net_device'
include/linux/mroute_base.h:40: warning: Function parameter or member 'dev_tracker' not described in 'vif_device'

Would you mind following up? likely not worth re-spinning just for that.