netdev - Re: [PATCH net 2/4] ice: Stop processing VF messages during teardown

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Message-ID: <8568eb9755224d5062337ab67f8a7a709ac2f2d8.camel@intel.com>
Date:   Tue, 10 Aug 2021 17:42:03 +0000
From:   "Venkataramanan, Anirudh" <anirudh.venkataramanan@...el.com>
To:     "kuba@...nel.org" <kuba@...nel.org>,
        "Nguyen, Anthony L" <anthony.l.nguyen@...el.com>
CC:     "davem@...emloft.net" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "Jankowski, Konrad0" <konrad0.jankowski@...el.com>
Subject: Re: [PATCH net 2/4] ice: Stop processing VF messages during teardown

On Mon, 2021-08-09 at 15:58 -0700, Jakub Kicinski wrote:
> On Mon,  9 Aug 2021 10:14:00 -0700 Tony Nguyen wrote:
> > When VFs are setup and torn down in quick succession, it is
> > possible
> > that a VF is torn down by the PF while the VF's virtchnl requests
> > are
> > still in the PF's mailbox ring. Processing the VF's virtchnl
> > request
> > when the VF itself doesn't exist results in undefined behavior. Fix
> > this by adding a check to stop processing virtchnl requests when VF
> > teardown is in progress.
> 
> What is "undefined behavior" in this context? Please improve the
> commit
> message. It should describe misbehavior visible to the user, failing
> that what will happen from kernel/device perspective. Or state that
> it's
> just a "fix" to align with some internal driver <> firmware spec...

Three different call traces were reported, and that's the reason I
chose to say "undefined behavior" which I suppose isn't very helpful.
Will update the commit message to include more details.

Ani