linux-kernel - RE: [EXT] Re: [PATCH v2 net 1/1] net: fec: using the standard return codes when xdp xmit errors

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Message-ID: <PAXPR04MB918534FB41385DC5353431E289749@PAXPR04MB9185.eurprd04.prod.outlook.com>
Date:   Thu, 11 May 2023 13:54:57 +0000
From:   Shenwei Wang <shenwei.wang@....com>
To:     Horatiu Vultur <horatiu.vultur@...rochip.com>
CC:     Wei Fang <wei.fang@....com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Clark Wang <xiaoning.wang@....com>,
        dl-linux-imx <linux-imx@....com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        John Fastabend <john.fastabend@...il.com>,
        Alexander Lobakin <alexandr.lobakin@...el.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "imx@...ts.linux.dev" <imx@...ts.linux.dev>
Subject: RE: [EXT] Re: [PATCH v2 net 1/1] net: fec: using the standard return
 codes when xdp xmit errors



> -----Original Message-----
> From: Horatiu Vultur <horatiu.vultur@...rochip.com>
> Sent: Thursday, May 11, 2023 2:25 AM
> To: Shenwei Wang <shenwei.wang@....com>
> Cc: Wei Fang <wei.fang@....com>; David S. Miller <davem@...emloft.net>;
> Eric Dumazet <edumazet@...gle.com>; Jakub Kicinski <kuba@...nel.org>;
> Paolo Abeni <pabeni@...hat.com>; Clark Wang <xiaoning.wang@....com>; dl-
> linux-imx <linux-imx@....com>; Alexei Starovoitov <ast@...nel.org>; Daniel
> Borkmann <daniel@...earbox.net>; Jesper Dangaard Brouer
> <hawk@...nel.org>; John Fastabend <john.fastabend@...il.com>; Alexander
> Lobakin <alexandr.lobakin@...el.com>; netdev@...r.kernel.org; linux-
> kernel@...r.kernel.org; imx@...ts.linux.dev
> Subject: [EXT] Re: [PATCH v2 net 1/1] net: fec: using the standard return codes
> when xdp xmit errors
>
> Caution: This is an external email. Please take care when clicking links or
> opening attachments. When in doubt, report the message using the 'Report this
> email' button
>
>
> The 05/10/2023 15:05, Shenwei Wang wrote:
> >
> > This patch standardizes the inconsistent return values for
> > unsuccessful XDP transmits by using standardized error codes (-EBUSY or -
> ENOMEM).
>
> Shouldn't this patch target net-next instead of net? As Simon suggested here [1],
> or maybe is just me who misunderstood that part.

-               xdp_return_frame(frame);
-               return NETDEV_TX_BUSY;
+               return -EBUSY;
As the "xdp_return_frame(frame)" should not be called when error branch, the patch
fix it too.

> Also it is nice to CC people who comment at your previous patches in all the next
> versions.
>
> Just a small thing, if there is only 1 patch in the series, you don't need to add 1/1
> in the subject.
>

The patch was generated by using "git format-patch -n1". The strange thing is that
it appends "1/1" on some machines but not on others. The output seems inconsistent.
However, using "git format-patch -N1" can fix this.

Thanks,
Shenwei

> [1]
> https://lore.kern/
> el.org%2Fnetdev%2F20230509193845.1090040-1-
> shenwei.wang%40nxp.com%2FT%2F%23m4b6b21c75512391496294fc78db2fbd
> f687f1381&data=05%7C01%7Cshenwei.wang%40nxp.com%7Ca92a1dbe84f348
> 42e79e08db51f0d24f%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C
> 638193866998878533%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMD
> AiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&s
> data=MO7RbDtCUU82clB2CyltzpvEdc7%2FjwLWvcCzgGN8mDc%3D&reserved=0
>
> >
> > Fixes: 26312c685ae0 ("net: fec: correct the counting of XDP sent
> > frames")
> > Signed-off-by: Shenwei Wang <shenwei.wang@....com>
> > ---
> >  v2:
> >   - focusing on code clean up per Simon's feedback.
> >
> >  drivers/net/ethernet/freescale/fec_main.c | 7 +++----
> >  1 file changed, 3 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/freescale/fec_main.c
> > b/drivers/net/ethernet/freescale/fec_main.c
> > index 42ec6ca3bf03..6a021fe24dfe 100644
> > --- a/drivers/net/ethernet/freescale/fec_main.c
> > +++ b/drivers/net/ethernet/freescale/fec_main.c
> > @@ -3798,8 +3798,7 @@ static int fec_enet_txq_xmit_frame(struct
> fec_enet_private *fep,
> >         entries_free = fec_enet_get_free_txdesc_num(txq);
> >         if (entries_free < MAX_SKB_FRAGS + 1) {
> >                 netdev_err(fep->netdev, "NOT enough BD for SG!\n");
> > -               xdp_return_frame(frame);
> > -               return NETDEV_TX_BUSY;
> > +               return -EBUSY;
> >         }
> >
> >         /* Fill in a Tx ring entry */
> > @@ -3813,7 +3812,7 @@ static int fec_enet_txq_xmit_frame(struct
> fec_enet_private *fep,
> >         dma_addr = dma_map_single(&fep->pdev->dev, frame->data,
> >                                   frame->len, DMA_TO_DEVICE);
> >         if (dma_mapping_error(&fep->pdev->dev, dma_addr))
> > -               return FEC_ENET_XDP_CONSUMED;
> > +               return -ENOMEM;
> >
> >         status |= (BD_ENET_TX_INTR | BD_ENET_TX_LAST);
> >         if (fep->bufdesc_ex)
> > @@ -3869,7 +3868,7 @@ static int fec_enet_xdp_xmit(struct net_device *dev,
> >         __netif_tx_lock(nq, cpu);
> >
> >         for (i = 0; i < num_frames; i++) {
> > -               if (fec_enet_txq_xmit_frame(fep, txq, frames[i]) != 0)
> > +               if (fec_enet_txq_xmit_frame(fep, txq, frames[i]) < 0)
> >                         break;
> >                 sent_frames++;
> >         }
> > --
> > 2.34.1
> >
> >
>
> --
> /Horatiu