netdev - Re: [PATCH net-next 0/3] eth: bnxt: handle invalid Tx completions more gracefully

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Message-ID: <CACKFLikt=1U5fB2Xe=KfsvjfrXmgQuR2PH4iWCESWcpZBf-8Qg@mail.gmail.com>
Date: Mon, 10 Jul 2023 14:44:31 -0700
From: Michael Chan <michael.chan@...adcom.com>
To: Jakub Kicinski <kuba@...nel.org>
Cc: davem@...emloft.net, netdev@...r.kernel.org, edumazet@...gle.com, 
	pabeni@...hat.com
Subject: Re: [PATCH net-next 0/3] eth: bnxt: handle invalid Tx completions
 more gracefully

On Mon, Jul 10, 2023 at 1:56 PM Jakub Kicinski <kuba@...nel.org> wrote:
>
> bnxt trusts the events generated by the device which may lead to kernel
> crashes. These are extremely rare but they do happen. For a while
> I thought crashing may be intentional, because device reporting invalid
> completions should never happen, and having a core dump could be useful
> if it does. But in practice I haven't found any clues in the core dumps,
> and panic_on_warn exists.

Indeed, it was intentional to crash the kernel so that we could
analyze the rings in the core dump.  Typically, we would find a bad
completion in one of the rings and we would debug it with the hardware
team during early chip testing.  Either the bug is fixed or some
suitable workaround is implemented.  Ideally, this should never happen
once the chip goes into production.

I suppose in a large enough deployment, this NULL SKB crash can
happen.  I will review your patchset later today.  Thanks.