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

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Date:   Fri, 10 Aug 2018 16:10:02 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Björn Töpel <bjorn.topel@...il.com>,
        ast@...com, netdev@...r.kernel.org, ap420073@...il.com,
        brouer@...hat.com
Cc:     Björn Töpel <bjorn.topel@...el.com>,
        magnus.karlsson@...el.com, magnus.karlsson@...il.com, kafai@...com
Subject: Re: [PATCH bpf] Revert "xdp: add NULL pointer check in
 __xdp_return()"

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!