From: Jakub Kicinski <kuba@kernel.org>
To: Thomas Osterried <thomas@osterried.de>
Cc: Eric Dumazet <edumazet@google.com>,
"David S . Miller" <davem@davemloft.net>,
Paolo Abeni <pabeni@redhat.com>, Bernard Pidoux <f6bvp@free.fr>,
Duoming Zhou <duoming@zju.edu.cn>,
netdev@vger.kernel.org, linux-hams@vger.kernel.org
Subject: Re: [AX25] patch did not fix -- was: ax25: fix incorrect dev_tracker usage
Date: Mon, 24 Oct 2022 13:56:40 -0700 [thread overview]
Message-ID: <20221024135640.73e5eddf@kernel.org> (raw)
In-Reply-To: <2B6541B7-FF35-41D2-8A20-18D5EEE7A919@osterried.de>
On Mon, 24 Oct 2022 20:00:00 +0200 Thomas Osterried wrote:
> II) What consequences has the tracker counter?
>
> As far as I can see by kernel messages, the netdev tracker forces the
> kernel to wait
> (on ifdown (i.e. ifconfig ax0 down)
> or rmmod (i.e. rmmod bpqether or rmmod ax25) )
> until all references to the network device are freed.
> If there's a bug (refcount > 0 or < 0), kernel obviously waits for ever.
Small correction here - the wait is when netdev is unregistered,
which often happens on rmmod, but also when user asks for a sw
netdev to be deleted, or HW device is removed, etc.
> III) Is it only to track sessions initiated from userspace?
>
> I think no.
Correct, the trackers track the references taken on the device.
Doesn't really matter if the reference is somehow tracable to
a user request or not.
Sorry for lack of input on the actual ax25 problem, I had looked
briefly in September and it wasn't obvious how things work :S
prev parent reply other threads:[~2022-10-24 20:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-10 7:16 [AX25] patch did not fix -- was: ax25: fix incorrect dev_tracker usage Thomas Osterried
2022-09-10 7:16 ` Thomas Osterried
2022-09-10 11:49 ` Thomas Osterried
2022-10-24 18:00 ` Thomas Osterried
2022-10-24 20:56 ` Jakub Kicinski [this message]
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