netdev - Re: [PATCH bpf] Revert "xdp: add NULL pointer check in __xdp

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Date:   Fri, 10 Aug 2018 17:16:45 +0200
From:   Björn Töpel <bjorn.topel@...il.com>
To:     Daniel Borkmann <daniel@...earbox.net>
Cc:     Alexei Starovoitov <ast@...com>, Netdev <netdev@...r.kernel.org>,
        Taehee Yoo <ap420073@...il.com>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Björn Töpel <bjorn.topel@...el.com>,
        "Karlsson, Magnus" <magnus.karlsson@...el.com>,
        Magnus Karlsson <magnus.karlsson@...il.com>, kafai@...com
Subject: Re: [PATCH bpf] Revert "xdp: add NULL pointer check in __xdp_return()"

Den fre 10 aug. 2018 kl 16:10 skrev Daniel Borkmann <daniel@...earbox.net>:
>
> On 08/10/2018 11:28 AM, Björn Töpel wrote:
> > From: Björn Töpel <bjorn.topel@...el.com>
> >
> > This reverts commit 36e0f12bbfd3016f495904b35e41c5711707509f.
> >
> > The reverted commit adds a WARN to check against NULL entries in the
> > mem_id_ht rhashtable. Any kernel path implementing the XDP (generic or
> > driver) fast path is required to make a paired
> > xdp_rxq_info_reg/xdp_rxq_info_unreg call for proper function. In
> > addition, a driver using a different allocation scheme than the
> > default MEM_TYPE_PAGE_SHARED is required to additionally call
> > xdp_rxq_info_reg_mem_model.
> >
> > For MEM_TYPE_ZERO_COPY, an xdp_rxq_info_reg_mem_model call ensures
> > that the mem_id_ht rhashtable has a properly inserted allocator id. If
> > not, this would be a driver bug. A NULL pointer kernel OOPS is
> > preferred to the WARN.
> >
> > Suggested-by: Jesper Dangaard Brouer <brouer@...hat.com>
> > Signed-off-by: Björn Töpel <bjorn.topel@...el.com>
>
> Given the last bpf pr went out yesterday night, I've applied this to
> bpf-next (worst case we can just route it via stable), thanks!

Ah, right! Thanks!

bpf-next is OK. (Since this path is currently not used yet by any driver... :-()


Björn