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Date:   Mon, 25 Apr 2022 08:00:57 -0700
From:   Jakub Kicinski <kuba@kernel.org>
To:     Jann Horn <jannh@google.com>
Cc:     Lukas Wunner <lukas@wunner.de>, Paolo Abeni <pabeni@redhat.com>,
        Oliver Neukum <oneukum@suse.com>,
        "David S. Miller" <davem@davemloft.net>,
        Oleksij Rempel <o.rempel@pengutronix.de>,
        Eric Dumazet <edumazet@google.com>, netdev@vger.kernel.org,
        linux-usb@vger.kernel.org, Andrew Lunn <andrew@lunn.ch>,
        Jacky Chou <jackychou@asix.com.tw>, Willy Tarreau <w@1wt.eu>,
        Lino Sanfilippo <LinoSanfilippo@gmx.de>,
        Philipp Rosenberger <p.rosenberger@kunbus.com>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH] net: linkwatch: ignore events for unregistered netdevs
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On Mon, 25 Apr 2022 16:49:34 +0200 Jann Horn wrote:
> > Doesn't mean we should make it legal. We can add a warning to catch
> > abuses.  
> 
> That was the idea with
> https://lore.kernel.org/netdev/20220128014303.2334568-1-jannh@google.com/,
> but I didn't get any replies when I asked what the precise semantics
> of dev_hold() are supposed to be
> (https://lore.kernel.org/netdev/CAG48ez1-OyZETvrYAfaHicYW1LbrQUVp=C0EukSWqZrYMej73w@mail.gmail.com/),
> so I don't know how to proceed...

Yeah, I think after you pointed out that the netdev per cpu refcounting
is fundamentally broken everybody decided to hit themselves with the
obliviate spell :S