From: Jesper Dangaard Brouer <brouer@redhat.com>
To: Lorenzo Bianconi <lorenzo@kernel.org>
Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, davem@davemloft.net,
lorenzo.bianconi@redhat.com, echaudro@redhat.com,
sameehj@amazon.com, kuba@kernel.org, brouer@redhat.com
Subject: Re: [PATCH net-next 0/6] mvneta: introduce XDP multi-buffer support
Date: Thu, 20 Aug 2020 15:16:44 +0200 [thread overview]
Message-ID: <20200820151644.00e6c87c@carbon> (raw)
In-Reply-To: <cover.1597842004.git.lorenzo@kernel.org>
General issue (that I think must be resolved/discussed as part of this initial
patchset).
When XDP_REDIRECT'ing a multi-buffer xdp_frame out of another driver's
ndo_xdp_xmit(), what happens if the remote driver doesn't understand the
multi-buffer format?
My guess it that it will only send the first part of the packet (in the
main page). Fortunately we don't leak memory, because xdp_return_frame()
handle freeing the other segments. I assume this isn't acceptable
behavior... or maybe it is?
What are our options for handling this:
1. Add mb support in ndo_xdp_xmit in every driver?
2. Drop xdp->mb frames inside ndo_xdp_xmit (in every driver without support)?
3. Add core-code check before calling ndo_xdp_xmit()?
--Jesper
On Wed, 19 Aug 2020 15:13:45 +0200 Lorenzo Bianconi <lorenzo@kernel.org> wrote:
> Finalize XDP multi-buffer support for mvneta driver introducing the capability
> to map non-linear buffers on tx side.
> Introduce multi-buffer bit (mb) in xdp_frame/xdp_buffer to specify if
> shared_info area has been properly initialized.
> Initialize multi-buffer bit (mb) to 0 in all XDP-capable drivers.
> Add multi-buff support to xdp_return_{buff/frame} utility routines.
>
> Changes since RFC:
> - squash multi-buffer bit initialization in a single patch
> - add mvneta non-linear XDP buff support for tx side
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer
next prev parent reply other threads:[~2020-08-20 13:17 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-19 13:13 [PATCH net-next 0/6] mvneta: introduce XDP multi-buffer support Lorenzo Bianconi
2020-08-19 13:13 ` [PATCH net-next 1/6] xdp: introduce mb in xdp_buff/xdp_frame Lorenzo Bianconi
2020-08-23 14:08 ` Shay Agroskin
2020-08-24 8:44 ` Jesper Dangaard Brouer
2020-08-26 9:47 ` Shay Agroskin
2020-08-19 13:13 ` [PATCH net-next 2/6] xdp: initialize xdp_buff mb bit to 0 in all XDP drivers Lorenzo Bianconi
2020-08-19 13:13 ` [PATCH net-next 3/6] net: mvneta: update mb bit before passing the xdp buffer to eBPF layer Lorenzo Bianconi
2020-08-20 8:02 ` Jesper Dangaard Brouer
2020-08-20 8:11 ` Lorenzo Bianconi
2020-08-20 19:38 ` Maciej Fijalkowski
2020-08-21 7:43 ` Lorenzo Bianconi
2020-08-19 13:13 ` [PATCH net-next 4/6] xdp: add multi-buff support to xdp_return_{buff/frame} Lorenzo Bianconi
2020-08-20 7:52 ` Jesper Dangaard Brouer
2020-08-20 7:56 ` Lorenzo Bianconi
2020-08-19 13:13 ` [PATCH net-next 5/6] net: mvneta: add multi buffer support to XDP_TX Lorenzo Bianconi
2020-08-19 13:13 ` [PATCH net-next 6/6] net: mvneta: enable jumbo frames for XDP Lorenzo Bianconi
2020-08-19 19:23 ` Jakub Kicinski
2020-08-19 20:22 ` Lorenzo Bianconi
2020-08-19 21:14 ` Jakub Kicinski
2020-08-19 21:58 ` John Fastabend
2020-08-20 7:47 ` Jesper Dangaard Brouer
2020-08-20 7:54 ` Lorenzo Bianconi
2020-08-20 13:16 ` Jesper Dangaard Brouer [this message]
2020-08-20 13:36 ` [PATCH net-next 0/6] mvneta: introduce XDP multi-buffer support Lorenzo Bianconi
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