From: Matteo Croce <mcroce@linux.microsoft.com>
To: Jakub Kicinski <kuba@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>,
Eric Dumazet <eric.dumazet@gmail.com>,
Thierry Reding <thierry.reding@gmail.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-riscv@lists.infradead.org,
Giuseppe Cavallaro <peppe.cavallaro@st.com>,
Alexandre Torgue <alexandre.torgue@foss.st.com>,
"David S. Miller" <davem@davemloft.net>,
Palmer Dabbelt <palmer@dabbelt.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Drew Fustini <drew@beagleboard.org>,
Emil Renner Berthing <kernel@esmil.dk>,
Jon Hunter <jonathanh@nvidia.com>, Will Deacon <will@kernel.org>
Subject: Re: [PATCH net-next] stmmac: align RX buffers
Date: Tue, 17 Aug 2021 02:01:57 +0200 [thread overview]
Message-ID: <20210817020157.3b9d015e@linux.microsoft.com> (raw)
In-Reply-To: <20210816081208.522ac47c@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
On Mon, 16 Aug 2021 08:12:08 -0700
Jakub Kicinski <kuba@kernel.org> wrote:
> On Thu, 12 Aug 2021 12:05:38 +0100 Marc Zyngier wrote:
> > > A possible fix, which takes in account also the XDP headroom for
> > > stmmac_rx_buf1_len() only could be (only compile tested, I don't
> > > have the hardware now):
> >
> > However, this doesn't fix my issue. I still get all sort of
> > corruption. Probably stmmac_rx_buf2_len() also need adjusting (it
> > has a similar logic as its buf1 counterpart...)
> >
> > Unless you can fix it very quickly, and given that we're towards the
> > end of the cycle, I'd be more comfortable if we reverted this patch.
>
> Any luck investigating this one? The rc6 announcement sounds like
> there may not be that many more rc releases for 5.14.
Hi Jackub.
Unfortunately I have only a device with stmmac, and it works fine with
the patch. It seems that not all hardware suffers from this issue.
Also, using NET_IP_ALIGN on RX is a common pattern, I think that any
ethernet device is doing the same to align the IPv4 header.
Anyway, I asked for two tests on the affected device:
1. Change NET_IP_ALIGN with 8, to see if the DMA has problems in
receiving to a non word aligned address
2. load a nop XDP program (I provided one), to see if the problem is
already there when XDP is used
I doubt that changing also stmmac_rx_buf2_len would help,
but it's worth a try, here is a patch:
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 7b8404a21544..73d1f0ec66ff 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -93,7 +93,7 @@ static int tc = TC_DEFAULT;
module_param(tc, int, 0644);
MODULE_PARM_DESC(tc, "DMA threshold control value");
-#define DEFAULT_BUFSIZE 1536
+#define DEFAULT_BUFSIZE 1536 + XDP_PACKET_HEADROOM + NET_IP_ALIGN
static int buf_sz = DEFAULT_BUFSIZE;
module_param(buf_sz, int, 0644);
MODULE_PARM_DESC(buf_sz, "DMA buffer size");
@@ -4508,12 +4508,12 @@ static unsigned int stmmac_rx_buf1_len(struct stmmac_priv *priv,
/* First descriptor, not last descriptor and not split header */
if (status & rx_not_ls)
- return priv->dma_buf_sz;
+ return priv->dma_buf_sz - stmmac_rx_offset(priv);
plen = stmmac_get_rx_frame_len(priv, p, coe);
/* First descriptor and last descriptor and not split header */
- return min_t(unsigned int, priv->dma_buf_sz, plen);
+ return min_t(unsigned int, priv->dma_buf_sz - stmmac_rx_offset(priv), plen);
}
static unsigned int stmmac_rx_buf2_len(struct stmmac_priv *priv,
@@ -4529,12 +4529,12 @@ static unsigned int stmmac_rx_buf2_len(struct stmmac_priv *priv,
/* Not last descriptor */
if (status & rx_not_ls)
- return priv->dma_buf_sz;
+ return priv->dma_buf_sz - stmmac_rx_offset(priv);
plen = stmmac_get_rx_frame_len(priv, p, coe);
/* Last descriptor */
- return plen - len;
+ return plen - len - stmmac_rx_offset(priv);
}
static int stmmac_xdp_xmit_xdpf(struct stmmac_priv *priv, int queue,
Regards,
--
per aspera ad upstream
next prev parent reply other threads:[~2021-08-17 0:02 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-14 2:25 [PATCH net-next] stmmac: align RX buffers Matteo Croce
2021-06-14 19:51 ` David Miller
2021-06-14 23:21 ` Matteo Croce
2021-06-15 17:28 ` David Miller
2021-06-15 17:30 ` patchwork-bot+netdevbpf
2021-08-10 19:07 ` Marc Zyngier
2021-08-11 10:28 ` Thierry Reding
2021-08-11 12:53 ` Eric Dumazet
2021-08-11 14:16 ` Marc Zyngier
2021-08-12 8:48 ` Eric Dumazet
2021-08-12 10:18 ` Matteo Croce
2021-08-12 11:05 ` Marc Zyngier
2021-08-12 11:18 ` Matteo Croce
2021-08-19 16:29 ` Marc Zyngier
2021-08-20 10:37 ` Matteo Croce
2021-08-20 16:26 ` Marc Zyngier
2021-08-20 16:38 ` Matteo Croce
2021-08-20 17:09 ` Marc Zyngier
2021-08-20 17:14 ` Matteo Croce
2021-08-20 17:24 ` Marc Zyngier
2021-08-20 17:35 ` Matteo Croce
2021-08-20 17:51 ` Marc Zyngier
2021-08-20 17:56 ` Matteo Croce
2021-08-20 18:05 ` Matteo Croce
2021-08-20 18:14 ` Marc Zyngier
2021-08-20 18:09 ` Marc Zyngier
2021-08-20 18:14 ` Matteo Croce
2021-08-20 18:41 ` Marc Zyngier
2021-08-16 15:12 ` Jakub Kicinski
2021-08-17 0:01 ` Matteo Croce [this message]
2021-08-19 15:26 ` Marc Zyngier
2021-08-11 10:41 ` Thierry Reding
2021-08-11 10:56 ` Joakim Zhang
2021-08-11 13:23 ` Marc Zyngier
2021-08-12 14:29 ` Thierry Reding
2021-08-12 15:26 ` Marc Zyngier
2021-08-13 14:44 ` Thierry Reding
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