* Re: [PATCH bpf] ice: xsk: do not use xdp_return_frame() on tx_buf->raw_buf
[not found] ` <LO4P265MB3758A8524A7C978D214D468B87129@LO4P265MB3758.GBRP265.PROD.OUTLOOK.COM>
@ 2022-11-29 16:04 ` Maciej Fijalkowski
0 siblings, 0 replies; 2+ messages in thread
From: Maciej Fijalkowski @ 2022-11-29 16:04 UTC (permalink / raw)
To: Robin Cowley; +Cc: magnus.karlsson@intel.com, xdp-newbies@vger.kernel.org
On Tue, Nov 29, 2022 at 03:48:44PM +0000, Robin Cowley wrote:
> Hi Maciej,
>
> I've just tested the patch you supplied and that seems to have worked perfectly when using multi FCQs.
> Thank you getting back so quickly with the patch.
Awesome. I will add your tag to commit message and send it to upstream.
Thanks for giving it a spin!
>
> Thanks,
> Robin
> ________________________________
> From: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
> Sent: 29 November 2022 14:25
> To: Robin Cowley <Robin.Cowley@thehutgroup.com>; magnus.karlsson@intel.com <magnus.karlsson@intel.com>
> Cc: xdp-newbies@vger.kernel.org <xdp-newbies@vger.kernel.org>; Maciej Fijalkowski <maciej.fijalkowski@intel.com>
> Subject: [PATCH bpf] ice: xsk: do not use xdp_return_frame() on tx_buf->raw_buf
>
> CAUTION: This email originates from outside THG
>
> Previously ice XDP xmit routine was changed in a way that it avoids
> xdp_buff->xdp_frame conversion as it is simply not needed for handling
> XDP_TX action and what is more it saves us CPU cycles. This routine is
> re-used on ZC driver to handle XDP_TX action.
>
> Although for XDP_TX on Rx ZC xdp_buff that comes from xsk_buff_pool is
> converted to xdp_frame, xdp_frame itself is not stored inside
> ice_tx_buf, we only store raw data pointer. Casting this pointer to
> xdp_frame and calling against it xdp_return_frame in
> ice_clean_xdp_tx_buf() results in undefined behavior.
>
> To fix this, simply call page_frag_free() on tx_buf->raw_buf.
> Later intention is to remove the buff->frame conversion in order to
> simplify the codebase and improve XDP_TX performance on ZC.
>
> Fixes: 126cdfe1007a ("ice: xsk: Improve AF_XDP ZC Tx and use batching API")
> Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
> ---
> drivers/net/ethernet/intel/ice/ice_xsk.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/intel/ice/ice_xsk.c b/drivers/net/ethernet/intel/ice/ice_xsk.c
> index 056c904b83cc..79fa65d1cf20 100644
> --- a/drivers/net/ethernet/intel/ice/ice_xsk.c
> +++ b/drivers/net/ethernet/intel/ice/ice_xsk.c
> @@ -772,7 +772,7 @@ int ice_clean_rx_irq_zc(struct ice_rx_ring *rx_ring, int budget)
> static void
> ice_clean_xdp_tx_buf(struct ice_tx_ring *xdp_ring, struct ice_tx_buf *tx_buf)
> {
> - xdp_return_frame((struct xdp_frame *)tx_buf->raw_buf);
> + page_frag_free(tx_buf->raw_buf);
> xdp_ring->xdp_tx_active--;
> dma_unmap_single(xdp_ring->dev, dma_unmap_addr(tx_buf, dma),
> dma_unmap_len(tx_buf, len), DMA_TO_DEVICE);
> --
> 2.34.1
>
>
> Robin Cowley
> Software Engineer
> The Hut Group<http://www.thehutgroup.com/>
>
> Tel:
> Email: Robin.Cowley@thehutgroup.com<mailto:Robin.Cowley@thehutgroup.com>
>
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