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Message-ID: <20210315212822.dibkci35efm5kgpy@skbuf>
Date: Mon, 15 Mar 2021 23:28:22 +0200
From: Vladimir Oltean <olteanv@...il.com>
To: Álvaro Fernández Rojas <noltari@...il.com>
Cc: jonas.gorski@...il.com, Florian Fainelli <f.fainelli@...il.com>,
Andrew Lunn <andrew@...n.ch>,
Vivien Didelot <vivien.didelot@...il.com>,
"David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 1/2] net: dsa: tag_brcm: add support for legacy
tags
On Mon, Mar 15, 2021 at 03:27:35PM +0100, Álvaro Fernández Rojas wrote:
> Add support for legacy Broadcom tags, which are similar to DSA_TAG_PROTO_BRCM.
> These tags are used on BCM5325, BCM5365 and BCM63xx switches.
>
> Signed-off-by: Álvaro Fernández Rojas <noltari@...il.com>
> ---
> include/net/dsa.h | 2 +
> net/dsa/Kconfig | 7 ++++
> net/dsa/tag_brcm.c | 96 ++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 105 insertions(+)
>
> diff --git a/include/net/dsa.h b/include/net/dsa.h
> index 83a933e563fe..dac303edd33d 100644
> --- a/include/net/dsa.h
> +++ b/include/net/dsa.h
> @@ -49,10 +49,12 @@ struct phylink_link_state;
> #define DSA_TAG_PROTO_XRS700X_VALUE 19
> #define DSA_TAG_PROTO_OCELOT_8021Q_VALUE 20
> #define DSA_TAG_PROTO_SEVILLE_VALUE 21
> +#define DSA_TAG_PROTO_BRCM_LEGACY_VALUE 22
>
> enum dsa_tag_protocol {
> DSA_TAG_PROTO_NONE = DSA_TAG_PROTO_NONE_VALUE,
> DSA_TAG_PROTO_BRCM = DSA_TAG_PROTO_BRCM_VALUE,
> + DSA_TAG_PROTO_BRCM_LEGACY = DSA_TAG_PROTO_BRCM_LEGACY_VALUE,
Is there no better qualifier for this tagging protocol name than "legacy"?
> DSA_TAG_PROTO_BRCM_PREPEND = DSA_TAG_PROTO_BRCM_PREPEND_VALUE,
> DSA_TAG_PROTO_DSA = DSA_TAG_PROTO_DSA_VALUE,
> DSA_TAG_PROTO_EDSA = DSA_TAG_PROTO_EDSA_VALUE,
> diff --git a/net/dsa/Kconfig b/net/dsa/Kconfig
> index 58b8fc82cd3c..aaf8a452fd5b 100644
> --- a/net/dsa/Kconfig
> +++ b/net/dsa/Kconfig
> @@ -48,6 +48,13 @@ config NET_DSA_TAG_BRCM
> Say Y if you want to enable support for tagging frames for the
> Broadcom switches which place the tag after the MAC source address.
>
> +config NET_DSA_TAG_BRCM_LEGACY
> + tristate "Tag driver for Broadcom legacy switches using in-frame headers"
Aren't all headers in-frame?
> + select NET_DSA_TAG_BRCM_COMMON
> + help
> + Say Y if you want to enable support for tagging frames for the
> + Broadcom legacy switches which place the tag after the MAC source
> + address.
>
> config NET_DSA_TAG_BRCM_PREPEND
> tristate "Tag driver for Broadcom switches using prepended headers"
> diff --git a/net/dsa/tag_brcm.c b/net/dsa/tag_brcm.c
> index e2577a7dcbca..9dbff771c9b3 100644
> --- a/net/dsa/tag_brcm.c
> +++ b/net/dsa/tag_brcm.c
> @@ -9,9 +9,23 @@
> #include <linux/etherdevice.h>
> #include <linux/list.h>
> #include <linux/slab.h>
> +#include <linux/types.h>
>
> #include "dsa_priv.h"
>
> +struct bcm_legacy_tag {
> + uint16_t type;
> +#define BRCM_LEG_TYPE 0x8874
> +
> + uint32_t tag;
> +#define BRCM_LEG_TAG_PORT_ID (0xf)
> +#define BRCM_LEG_TAG_MULTICAST (1 << 29)
> +#define BRCM_LEG_TAG_EGRESS (2 << 29)
> +#define BRCM_LEG_TAG_INGRESS (3 << 29)
> +} __attribute__((packed));
> +
> +#define BRCM_LEG_TAG_LEN sizeof(struct bcm_legacy_tag)
> +
As Florian pointed out, tagging protocol parsing should be
endian-independent, and mapping a struct over the frame header is pretty
much not that.
> /* This tag length is 4 bytes, older ones were 6 bytes, we do not
> * handle them
> */
> @@ -195,6 +209,85 @@ DSA_TAG_DRIVER(brcm_netdev_ops);
> MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM);
> #endif
>
> +#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_LEGACY)
> +static struct sk_buff *brcm_leg_tag_xmit(struct sk_buff *skb,
> + struct net_device *dev)
> +{
> + struct dsa_port *dp = dsa_slave_to_port(dev);
> + struct bcm_legacy_tag *brcm_tag;
> +
> + if (skb_cow_head(skb, BRCM_LEG_TAG_LEN) < 0)
> + return NULL;
This is not needed since commit 2f0d030c5ffe ("net: dsa: tag_brcm: let
DSA core deal with TX reallocation").
> + /* The Ethernet switch we are interfaced with needs packets to be at
> + * least 64 bytes (including FCS) otherwise they will be discarded when
> + * they enter the switch port logic. When Broadcom tags are enabled, we
> + * need to make sure that packets are at least 70 bytes
> + * (including FCS and tag) because the length verification is done after
> + * the Broadcom tag is stripped off the ingress packet.
> + *
> + * Let dsa_slave_xmit() free the SKB
> + */
> + if (__skb_put_padto(skb, ETH_ZLEN + BRCM_LEG_TAG_LEN, false))
> + return NULL;
Are you sure the switches you're working on need this, or is it just
another copy-pasta?
> + skb_push(skb, BRCM_LEG_TAG_LEN);
> +
> + memmove(skb->data, skb->data + BRCM_LEG_TAG_LEN, 2 * ETH_ALEN);
> +
> + brcm_tag = (struct bcm_legacy_tag *) (skb->data + 2 * ETH_ALEN);
> +
> + brcm_tag->type = BRCM_LEG_TYPE;
> + brcm_tag->tag = BRCM_LEG_TAG_EGRESS;
> + brcm_tag->tag |= dp->index & BRCM_LEG_TAG_PORT_ID;
> +
> + return skb;
> +}
> +
> +
Please remove the extra newline.
> +static struct sk_buff *brcm_leg_tag_rcv(struct sk_buff *skb,
> + struct net_device *dev,
> + struct packet_type *pt)
> +{
> + int source_port;
> + struct bcm_legacy_tag *brcm_tag;
Please declare the local variables in the order of decreasing line length.
> +
> + if (unlikely(!pskb_may_pull(skb, BRCM_LEG_TAG_LEN)))
> + return NULL;
> +
> + brcm_tag = (struct bcm_legacy_tag *) (skb->data - 2);
Nitpick: the space between the *) and the (skb-> is not needed.
> +
> + source_port = brcm_tag->tag & BRCM_LEG_TAG_PORT_ID;
> +
> + skb->dev = dsa_master_find_slave(dev, 0, source_port);
> + if (!skb->dev)
> + return NULL;
> +
> + /* Remove Broadcom tag and update checksum */
> + skb_pull_rcsum(skb, BRCM_LEG_TAG_LEN);
> +
> + skb->offload_fwd_mark = 1;
> +
> + /* Move the Ethernet DA and SA */
> + memmove(skb->data - ETH_HLEN,
> + skb->data - ETH_HLEN - BRCM_LEG_TAG_LEN,
> + 2 * ETH_ALEN);
> +
> + return skb;
> +}
> +
> +static const struct dsa_device_ops brcm_legacy_netdev_ops = {
> + .name = "brcm-legacy",
> + .proto = DSA_TAG_PROTO_BRCM_LEGACY,
> + .xmit = brcm_leg_tag_xmit,
> + .rcv = brcm_leg_tag_rcv,
> + .overhead = BRCM_LEG_TAG_LEN,
> +};
> +
> +DSA_TAG_DRIVER(brcm_legacy_netdev_ops);
> +MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM_LEGACY);
> +#endif /* CONFIG_NET_DSA_TAG_BRCM_LEGACY */
> +
> #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)
> static struct sk_buff *brcm_tag_xmit_prepend(struct sk_buff *skb,
> struct net_device *dev)
> @@ -227,6 +320,9 @@ static struct dsa_tag_driver *dsa_tag_driver_array[] = {
> #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM)
> &DSA_TAG_DRIVER_NAME(brcm_netdev_ops),
> #endif
> +#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_LEGACY)
> + &DSA_TAG_DRIVER_NAME(brcm_legacy_netdev_ops),
> +#endif
> #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)
> &DSA_TAG_DRIVER_NAME(brcm_prepend_netdev_ops),
> #endif
> --
> 2.20.1
>
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