RE: [Intel-wired-lan] [PATCH net] ice: Fix incorrect locking in ice_vc_process_vf_msg()

[Keller, Jacob E]

> -----Original Message-----
> From: Brett Creeley <brett@xxxxxxxxxxx>
> Sent: Thursday, March 31, 2022 9:33 AM
> To: Fijalkowski, Maciej <maciej.fijalkowski@xxxxxxxxx>
> Cc: ivecera <ivecera@xxxxxxxxxx>; netdev@xxxxxxxxxxxxxxx; moderated
> list:INTEL ETHERNET DRIVERS <intel-wired-lan@xxxxxxxxxxxxxxxx>; mschmidt
> <mschmidt@xxxxxxxxxx>; open list <linux-kernel@xxxxxxxxxxxxxxx>; poros
> <poros@xxxxxxxxxx>; Jakub Kicinski <kuba@xxxxxxxxxx>; Paolo Abeni
> <pabeni@xxxxxxxxxx>; David S. Miller <davem@xxxxxxxxxxxxx>; Keller, Jacob E
> <jacob.e.keller@xxxxxxxxx>
> Subject: Re: [Intel-wired-lan] [PATCH net] ice: Fix incorrect locking in
> ice_vc_process_vf_msg()
> 
> On Thu, Mar 31, 2022 at 6:17 AM Maciej Fijalkowski
> <maciej.fijalkowski@xxxxxxxxx> wrote:
> >
> > On Thu, Mar 31, 2022 at 03:14:32PM +0200, Maciej Fijalkowski wrote:
> > > On Thu, Mar 31, 2022 at 12:50:04PM +0200, Ivan Vecera wrote:
> > > > Usage of mutex_trylock() in ice_vc_process_vf_msg() is incorrect
> > > > because message sent from VF is ignored and never processed.
> > > >
> > > > Use mutex_lock() instead to fix the issue. It is safe because this
> > >
> > > We need to know what is *the* issue in the first place.
> > > Could you please provide more context what is being fixed to the readers
> > > that don't have an access to bugzilla?
> > >
> > > Specifically, what is the case that ignoring a particular message when
> > > mutex is already held is a broken behavior?
> >
> > Uh oh, let's
> > CC: Brett Creeley <brett@xxxxxxxxxxx>
>

Thanks for responding, Brett! :)
 
> My concern here is that we don't want to handle messages
> from the context of the "previous" VF configuration if that
> makes sense.
> 

Makes sense. Perhaps we need to do some sort of "clear the existing message queue" when we initiate a reset?

> It might be best to grab the cfg_lock before doing any
> message/VF validating in ice_vc_process_vf_msg() to
> make sure all of the checks are done under the cfg_lock.
> 

Yes that seems like it should be done.

> CC'ing Jake so he can provide some input as
> well.

Thanks,
Jake