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Date:   Fri, 10 Apr 2020 08:15:06 +0000
From:   Ariel Elior <aelior@...vell.com>
To:     Jakub Kicinski <kuba@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>
CC:     Christian Deacon <gamemann@...clan.com>,
        "bpf@...r.kernel.org" <bpf@...r.kernel.org>,
        Sudarsana Reddy Kalluru <skalluru@...vell.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [EXT] Re: TC BPF Program Crashing With Bnx2x Drivers

> -----Original Message-----
> From: Jakub Kicinski <kuba@...nel.org>
> Sent: Thursday, April 9, 2020 10:18 PM
> To: Daniel Borkmann <daniel@...earbox.net>
> Cc: Christian Deacon <gamemann@...clan.com>; bpf@...r.kernel.org; Ariel
> Elior <aelior@...vell.com>; Sudarsana Reddy Kalluru
> <skalluru@...vell.com>; netdev@...r.kernel.org
> Subject: [EXT] Re: TC BPF Program Crashing With Bnx2x Drivers
> 
> External Email
> 
> ----------------------------------------------------------------------
> On Thu, 9 Apr 2020 01:57:42 +0200 Daniel Borkmann wrote:
> > On 4/9/20 1:30 AM, Christian Deacon wrote:
> > > Hey Daniel,
> > >
> > >
> > > Thank you for your response and I'm glad I'm in the correct area!
> > >
> > >
> > > When the individual ran:
> > >
> > >
> > > ```
> > >
> > > ethtool -K eth0 tso off
> > >
> > > ```
> > >
> > >
> > > The program started operating without crashing. It has been around 20
> minutes so far and no crash. Therefore, I'd assume that stopped the crashing
> considering it usually crashed 20 - 30 seconds after starting the program each
> time beforehand. I'm not entirely sure what TSO does with this network driver,
> but I'll try doing some research.
> >
> > Yep, don't think it should crash anymore after you turned it off and
> > it survived since then. ;) I presume GSO is still on in your case,
> > right (check via `ethtool -k eth0`)?
> >
> > > I was suspecting it may be the 'bpf_skb_adjust_room()' function as
> > > well since I'm using a mode that was implemented in later kernels.
> > > This function removes the outer IP header in my program from the
> > > outgoing IPIP packet. I'm not sure what would be causing the
> > > crashing, though.
> >
> > Probably bnx2x folks might be able to help but as mentioned looks
> > like the tso handling in there has an issue with the ipip which leads
> > to the nic hang eventually.
> 
> IMHO this is not a bnx2x problem. The drivers should not have to
> re-validate GSO flags..
> 
> Let's see if I get this right. We have an IPinIP encap, IPXIP4 GSO skb
> comes down and TC bpf pulls the outer header off, but the gso flags
> remain unchanged. The driver then sees IPXIP4 GSO but there are no
> headers so it implodes. Is this correct?
> 
> And we have the ability to add the right gso flags for encap, not decap
> (bpf_skb_net_grow() vs bpf_skb_net_shrink()).

Hi,
I would still like to get an ethtool -d output after this happens, to review
the device state. Even if the skb was illegal, the error we got was device
crash, which seems too severe. I wonder what would happen if a VF
would provide such an SKB.
Thanks,
Ariel

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