| Message ID | 20230207103027.1203344-1-vladimir.oltean@nxp.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [net] net: ethernet: mtk_eth_soc: fix DSA TX tag hwaccel for switch port 0 | expand |
On 07.02.23 11:30, Vladimir Oltean wrote: > Arınç reports that on his MT7621AT Unielec U7621-06 board and MT7623NI > Bananapi BPI-R2, packets received by the CPU over mt7530 switch port 0 > (of which this driver acts as the DSA master) are not processed > correctly by software. More precisely, they arrive without a DSA tag > (in packet or in the hwaccel area - skb_metadata_dst()), so DSA cannot > demux them towards the switch's interface for port 0. Traffic from other > ports receives a skb_metadata_dst() with the correct port and is demuxed > properly. > > Looking at mtk_poll_rx(), it becomes apparent that this driver uses the > skb vlan hwaccel area: > > union { > u32 vlan_all; > struct { > __be16 vlan_proto; > __u16 vlan_tci; > }; > }; > > as a temporary storage for the VLAN hwaccel tag, or the DSA hwaccel tag. > If this is a DSA master it's a DSA hwaccel tag, and finally clears up > the skb VLAN hwaccel header. > > I'm guessing that the problem is the (mis)use of API. > skb_vlan_tag_present() looks like this: > > #define skb_vlan_tag_present(__skb) (!!(__skb)->vlan_all) > > So if both vlan_proto and vlan_tci are zeroes, skb_vlan_tag_present() > returns precisely false. I don't know for sure what is the format of the > DSA hwaccel tag, but I surely know that lowermost 3 bits of vlan_proto > are 0 when receiving from port 0: > > unsigned int port = vlan_proto & GENMASK(2, 0); > > If the RX descriptor has no other bits set to non-zero values in > RX_DMA_VTAG, then the call to __vlan_hwaccel_put_tag() will not, in > fact, make the subsequent skb_vlan_tag_present() return true, because > it's implemented like this: > > static inline void __vlan_hwaccel_put_tag(struct sk_buff *skb, > __be16 vlan_proto, u16 vlan_tci) > { > skb->vlan_proto = vlan_proto; > skb->vlan_tci = vlan_tci; > } > > What we need to do to fix this problem (assuming this is the problem) is > to stop using skb->vlan_all as temporary storage for driver affairs, and > just create some local variables that serve the same purpose, but > hopefully better. Instead of calling skb_vlan_tag_present(), let's look > at a boolean has_hwaccel_tag which we set to true when the RX DMA > descriptors have something. Disambiguate based on netdev_uses_dsa() > whether this is a VLAN or DSA hwaccel tag, and only call > __vlan_hwaccel_put_tag() if we're certain it's a VLAN tag. > > Arınç confirms that the treatment works, so this validates the > assumption. > > Link: https://lore.kernel.org/netdev/704f3a72-fc9e-714a-db54-272e17612637@arinc9.com/ > Fixes: 2d7605a72906 ("net: ethernet: mtk_eth_soc: enable hardware DSA untagging") > Reported-by: Arınç ÜNAL <arinc.unal@arinc9.com> > Tested-by: Arınç ÜNAL <arinc.unal@arinc9.com> > Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Reviewed-by: Felix Fietkau <nbd@nbd.name>
Hello: This patch was applied to netdev/net.git (master) by David S. Miller <davem@davemloft.net>: On Tue, 7 Feb 2023 12:30:27 +0200 you wrote: > Arınç reports that on his MT7621AT Unielec U7621-06 board and MT7623NI > Bananapi BPI-R2, packets received by the CPU over mt7530 switch port 0 > (of which this driver acts as the DSA master) are not processed > correctly by software. More precisely, they arrive without a DSA tag > (in packet or in the hwaccel area - skb_metadata_dst()), so DSA cannot > demux them towards the switch's interface for port 0. Traffic from other > ports receives a skb_metadata_dst() with the correct port and is demuxed > properly. > > [...] Here is the summary with links: - [net] net: ethernet: mtk_eth_soc: fix DSA TX tag hwaccel for switch port 0 https://git.kernel.org/netdev/net/c/1a3245fe0cf8 You are awesome, thank you!
diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c index f1cb1efc94cf..64b575fbe317 100644 --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c @@ -1921,7 +1921,9 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget, while (done < budget) { unsigned int pktlen, *rxdcsum; + bool has_hwaccel_tag = false; struct net_device *netdev; + u16 vlan_proto, vlan_tci; dma_addr_t dma_addr; u32 hash, reason; int mac = 0; @@ -2061,27 +2063,29 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget, if (netdev->features & NETIF_F_HW_VLAN_CTAG_RX) { if (MTK_HAS_CAPS(eth->soc->caps, MTK_NETSYS_V2)) { - if (trxd.rxd3 & RX_DMA_VTAG_V2) - __vlan_hwaccel_put_tag(skb, - htons(RX_DMA_VPID(trxd.rxd4)), - RX_DMA_VID(trxd.rxd4)); + if (trxd.rxd3 & RX_DMA_VTAG_V2) { + vlan_proto = RX_DMA_VPID(trxd.rxd4); + vlan_tci = RX_DMA_VID(trxd.rxd4); + has_hwaccel_tag = true; + } } else if (trxd.rxd2 & RX_DMA_VTAG) { - __vlan_hwaccel_put_tag(skb, htons(RX_DMA_VPID(trxd.rxd3)), - RX_DMA_VID(trxd.rxd3)); + vlan_proto = RX_DMA_VPID(trxd.rxd3); + vlan_tci = RX_DMA_VID(trxd.rxd3); + has_hwaccel_tag = true; } } /* When using VLAN untagging in combination with DSA, the * hardware treats the MTK special tag as a VLAN and untags it. */ - if (skb_vlan_tag_present(skb) && netdev_uses_dsa(netdev)) { - unsigned int port = ntohs(skb->vlan_proto) & GENMASK(2, 0); + if (has_hwaccel_tag && netdev_uses_dsa(netdev)) { + unsigned int port = vlan_proto & GENMASK(2, 0); if (port < ARRAY_SIZE(eth->dsa_meta) && eth->dsa_meta[port]) skb_dst_set_noref(skb, ð->dsa_meta[port]->dst); - - __vlan_hwaccel_clear_tag(skb); + } else if (has_hwaccel_tag) { + __vlan_hwaccel_put_tag(skb, htons(vlan_proto), vlan_tci); } skb_record_rx_queue(skb, 0);
Arınç reports that on his MT7621AT Unielec U7621-06 board and MT7623NI Bananapi BPI-R2, packets received by the CPU over mt7530 switch port 0 (of which this driver acts as the DSA master) are not processed correctly by software. More precisely, they arrive without a DSA tag (in packet or in the hwaccel area - skb_metadata_dst()), so DSA cannot demux them towards the switch's interface for port 0. Traffic from other ports receives a skb_metadata_dst() with the correct port and is demuxed properly. Looking at mtk_poll_rx(), it becomes apparent that this driver uses the skb vlan hwaccel area: union { u32 vlan_all; struct { __be16 vlan_proto; __u16 vlan_tci; }; }; as a temporary storage for the VLAN hwaccel tag, or the DSA hwaccel tag. If this is a DSA master it's a DSA hwaccel tag, and finally clears up the skb VLAN hwaccel header. I'm guessing that the problem is the (mis)use of API. skb_vlan_tag_present() looks like this: #define skb_vlan_tag_present(__skb) (!!(__skb)->vlan_all) So if both vlan_proto and vlan_tci are zeroes, skb_vlan_tag_present() returns precisely false. I don't know for sure what is the format of the DSA hwaccel tag, but I surely know that lowermost 3 bits of vlan_proto are 0 when receiving from port 0: unsigned int port = vlan_proto & GENMASK(2, 0); If the RX descriptor has no other bits set to non-zero values in RX_DMA_VTAG, then the call to __vlan_hwaccel_put_tag() will not, in fact, make the subsequent skb_vlan_tag_present() return true, because it's implemented like this: static inline void __vlan_hwaccel_put_tag(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci) { skb->vlan_proto = vlan_proto; skb->vlan_tci = vlan_tci; } What we need to do to fix this problem (assuming this is the problem) is to stop using skb->vlan_all as temporary storage for driver affairs, and just create some local variables that serve the same purpose, but hopefully better. Instead of calling skb_vlan_tag_present(), let's look at a boolean has_hwaccel_tag which we set to true when the RX DMA descriptors have something. Disambiguate based on netdev_uses_dsa() whether this is a VLAN or DSA hwaccel tag, and only call __vlan_hwaccel_put_tag() if we're certain it's a VLAN tag. Arınç confirms that the treatment works, so this validates the assumption. Link: https://lore.kernel.org/netdev/704f3a72-fc9e-714a-db54-272e17612637@arinc9.com/ Fixes: 2d7605a72906 ("net: ethernet: mtk_eth_soc: enable hardware DSA untagging") Reported-by: Arınç ÜNAL <arinc.unal@arinc9.com> Tested-by: Arınç ÜNAL <arinc.unal@arinc9.com> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> --- drivers/net/ethernet/mediatek/mtk_eth_soc.c | 24 ++++++++++++--------- 1 file changed, 14 insertions(+), 10 deletions(-)