[PATCH net-next 0/4] net: dsa: Improve dsa_untag_bridge_pvid()

[PATCH net-next 0/4] net: dsa: Improve dsa_untag_bridge_pvid()

[Florian Fainelli]

Hi David, Jakub,

This patch series is based on the recent discussions with Vladimir:

https://lore.kernel.org/netdev/20201001030623.343535-1-f.fainelli@gmail.com/

the simplest way forward was to call dsa_untag_bridge_pvid() after
eth_type_trans() has been set which guarantees that skb->protocol is set
to a correct value and this allows us to utilize
__vlan_find_dev_deep_rcu() properly without playing or using the bridge
master as a net_device reference.

Florian Fainelli (4):
  net: dsa: Call dsa_untag_bridge_pvid() from dsa_switch_rcv()
  net: dsa: b53: Set untag_bridge_pvid
  net: dsa: Obtain VLAN protocol from skb->protocol
  net: dsa: Utilize __vlan_find_dev_deep_rcu()

 drivers/net/dsa/b53/b53_common.c |  1 +
 include/net/dsa.h                |  8 ++++++++
 net/dsa/dsa.c                    |  9 +++++++++
 net/dsa/dsa_priv.h               | 14 ++++----------
 net/dsa/tag_brcm.c               | 15 ++-------------
 5 files changed, 24 insertions(+), 23 deletions(-)

-- 
2.25.1

[PATCH net-next 1/4] net: dsa: Call dsa_untag_bridge_pvid() from dsa_switch_rcv()

[Florian Fainelli]

When a DSA switch driver needs to call dsa_untag_bridge_pvid(), it can
set dsa_switch::untag_brige_pvid to indicate this is necessary.

This is a pre-requisite to making sure that we are always calling
dsa_untag_bridge_pvid() after eth_type_trans() has been called.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 include/net/dsa.h | 8 ++++++++
 net/dsa/dsa.c     | 9 +++++++++
 2 files changed, 17 insertions(+)

diff --git a/include/net/dsa.h b/include/net/dsa.h
index b502a63d196e..8b0696e08cac 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -308,6 +308,14 @@ struct dsa_switch {
 	 */
 	bool			configure_vlan_while_not_filtering;
 
+	/* If the switch driver always programs the CPU port as egress tagged
+	 * despite the VLAN configuration indicating otherwise, then setting
+	 * @untag_bridge_pvid will force the DSA receive path to pop the bridge's
+	 * default_pvid VLAN tagged frames to offer a consistent behavior
+	 * between a vlan_filtering=0 and vlan_filtering=1 bridge device.
+	 */
+	bool			untag_bridge_pvid;
+
 	/* In case vlan_filtering_is_global is set, the VLAN awareness state
 	 * should be retrieved from here and not from the per-port settings.
 	 */
diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
index 5c18c0214aac..dec4ab59b7c4 100644
--- a/net/dsa/dsa.c
+++ b/net/dsa/dsa.c
@@ -225,6 +225,15 @@ static int dsa_switch_rcv(struct sk_buff *skb, struct net_device *dev,
 	skb->pkt_type = PACKET_HOST;
 	skb->protocol = eth_type_trans(skb, skb->dev);
 
+	if (unlikely(cpu_dp->ds->untag_bridge_pvid)) {
+		nskb = dsa_untag_bridge_pvid(skb);
+		if (!nskb) {
+			kfree_skb(skb);
+			return 0;
+		}
+		skb = nskb;
+	}
+
 	s = this_cpu_ptr(p->stats64);
 	u64_stats_update_begin(&s->syncp);
 	s->rx_packets++;
-- 
2.25.1

[PATCH net-next 2/4] net: dsa: b53: Set untag_bridge_pvid

[Florian Fainelli]

Indicate to the DSA receive path that we need to untage the bridge PVID,
this allows us to remove the dsa_untag_bridge_pvid() calls from
net/dsa/tag_brcm.c.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 drivers/net/dsa/b53/b53_common.c |  1 +
 net/dsa/tag_brcm.c               | 15 ++-------------
 2 files changed, 3 insertions(+), 13 deletions(-)

diff --git a/drivers/net/dsa/b53/b53_common.c b/drivers/net/dsa/b53/b53_common.c
index 73507cff3bc4..ce18ba0b74eb 100644
--- a/drivers/net/dsa/b53/b53_common.c
+++ b/drivers/net/dsa/b53/b53_common.c
@@ -2603,6 +2603,7 @@ struct b53_device *b53_switch_alloc(struct device *base,
 	dev->ops = ops;
 	ds->ops = &b53_switch_ops;
 	ds->configure_vlan_while_not_filtering = true;
+	ds->untag_bridge_pvid = true;
 	dev->vlan_enabled = ds->configure_vlan_while_not_filtering;
 	mutex_init(&dev->reg_mutex);
 	mutex_init(&dev->stats_mutex);
diff --git a/net/dsa/tag_brcm.c b/net/dsa/tag_brcm.c
index 69d6b8c597a9..ad72dff8d524 100644
--- a/net/dsa/tag_brcm.c
+++ b/net/dsa/tag_brcm.c
@@ -152,11 +152,6 @@ static struct sk_buff *brcm_tag_rcv_ll(struct sk_buff *skb,
 	/* Remove Broadcom tag and update checksum */
 	skb_pull_rcsum(skb, BRCM_TAG_LEN);
 
-	/* Set the MAC header to where it should point for
-	 * dsa_untag_bridge_pvid() to parse the correct VLAN header.
-	 */
-	skb_set_mac_header(skb, -ETH_HLEN);
-
 	skb->offload_fwd_mark = 1;
 
 	return skb;
@@ -187,7 +182,7 @@ static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
 		nskb->data - ETH_HLEN - BRCM_TAG_LEN,
 		2 * ETH_ALEN);
 
-	return dsa_untag_bridge_pvid(nskb);
+	return nskb;
 }
 
 static const struct dsa_device_ops brcm_netdev_ops = {
@@ -214,14 +209,8 @@ static struct sk_buff *brcm_tag_rcv_prepend(struct sk_buff *skb,
 					    struct net_device *dev,
 					    struct packet_type *pt)
 {
-	struct sk_buff *nskb;
-
 	/* tag is prepended to the packet */
-	nskb = brcm_tag_rcv_ll(skb, dev, pt, ETH_HLEN);
-	if (!nskb)
-		return nskb;
-
-	return dsa_untag_bridge_pvid(nskb);
+	return brcm_tag_rcv_ll(skb, dev, pt, ETH_HLEN);
 }
 
 static const struct dsa_device_ops brcm_prepend_netdev_ops = {
-- 
2.25.1

[PATCH net-next 3/4] net: dsa: Obtain VLAN protocol from skb->protocol

[Florian Fainelli]

Now that dsa_untag_bridge_pvid() is called after eth_type_trans() we are
guaranteed that skb->protocol will be set to a correct value, thus
allowing us to avoid calling vlan_eth_hdr().

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 net/dsa/dsa_priv.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
index 0348dbab4131..d6ce8c2a2590 100644
--- a/net/dsa/dsa_priv.h
+++ b/net/dsa/dsa_priv.h
@@ -201,7 +201,6 @@ dsa_slave_to_master(const struct net_device *dev)
 static inline struct sk_buff *dsa_untag_bridge_pvid(struct sk_buff *skb)
 {
 	struct dsa_port *dp = dsa_slave_to_port(skb->dev);
-	struct vlan_ethhdr *hdr = vlan_eth_hdr(skb);
 	struct net_device *br = dp->bridge_dev;
 	struct net_device *dev = skb->dev;
 	struct net_device *upper_dev;
@@ -217,7 +216,7 @@ static inline struct sk_buff *dsa_untag_bridge_pvid(struct sk_buff *skb)
 		return skb;
 
 	/* Move VLAN tag from data to hwaccel */
-	if (!skb_vlan_tag_present(skb) && hdr->h_vlan_proto == htons(proto)) {
+	if (!skb_vlan_tag_present(skb) && skb->protocol == htons(proto)) {
 		skb = skb_vlan_untag(skb);
 		if (!skb)
 			return NULL;
-- 
2.25.1

[PATCH net-next 4/4] net: dsa: Utilize __vlan_find_dev_deep_rcu()

[Florian Fainelli]

Now that we are guaranteed that dsa_untag_bridge_pvid() is called after
eth_type_trans() we can utilize __vlan_find_dev_deep_rcu() which will
take care of finding an 802.1Q upper on top of a bridge master.

A common use case, prior to 12a1526d067 ("net: dsa: untag the bridge
pvid from rx skbs") was to configure a bridge 802.1Q upper like this:

ip link add name br0 type bridge vlan_filtering 0
ip link add link br0 name br0.1 type vlan id 1

in order to pop the default_pvid VLAN tag.

With this change we restore that behavior while still allowing the DSA
receive path to automatically pop the VLAN tag.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 net/dsa/dsa_priv.h | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
index d6ce8c2a2590..12998bf04e55 100644
--- a/net/dsa/dsa_priv.h
+++ b/net/dsa/dsa_priv.h
@@ -204,7 +204,6 @@ static inline struct sk_buff *dsa_untag_bridge_pvid(struct sk_buff *skb)
 	struct net_device *br = dp->bridge_dev;
 	struct net_device *dev = skb->dev;
 	struct net_device *upper_dev;
-	struct list_head *iter;
 	u16 vid, pvid, proto;
 	int err;
 
@@ -246,13 +245,9 @@ static inline struct sk_buff *dsa_untag_bridge_pvid(struct sk_buff *skb)
 	 * supports because vlan_filtering is 0. In that case, we should
 	 * definitely keep the tag, to make sure it keeps working.
 	 */
-	netdev_for_each_upper_dev_rcu(dev, upper_dev, iter) {
-		if (!is_vlan_dev(upper_dev))
-			continue;
-
-		if (vid == vlan_dev_vlan_id(upper_dev))
-			return skb;
-	}
+	upper_dev = __vlan_find_dev_deep_rcu(br, htons(proto), vid);
+	if (upper_dev)
+		return skb;
 
 	__vlan_hwaccel_clear_tag(skb);
 
-- 
2.25.1

Re: [PATCH net-next 1/4] net: dsa: Call dsa_untag_bridge_pvid() from dsa_switch_rcv()

[Vladimir Oltean]

On Thu, Oct 01, 2020 at 07:42:12PM -0700, Florian Fainelli wrote:
> When a DSA switch driver needs to call dsa_untag_bridge_pvid(), it can
> set dsa_switch::untag_brige_pvid to indicate this is necessary.
> 
> This is a pre-requisite to making sure that we are always calling
> dsa_untag_bridge_pvid() after eth_type_trans() has been called.
> 
> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
> ---

Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>

>  include/net/dsa.h | 8 ++++++++
>  net/dsa/dsa.c     | 9 +++++++++
>  2 files changed, 17 insertions(+)
> 
> diff --git a/include/net/dsa.h b/include/net/dsa.h
> index b502a63d196e..8b0696e08cac 100644
> --- a/include/net/dsa.h
> +++ b/include/net/dsa.h
> @@ -308,6 +308,14 @@ struct dsa_switch {
>  	 */
>  	bool			configure_vlan_while_not_filtering;
>  
> +	/* If the switch driver always programs the CPU port as egress tagged
> +	 * despite the VLAN configuration indicating otherwise, then setting
> +	 * @untag_bridge_pvid will force the DSA receive path to pop the bridge's
> +	 * default_pvid VLAN tagged frames to offer a consistent behavior
> +	 * between a vlan_filtering=0 and vlan_filtering=1 bridge device.
> +	 */
> +	bool			untag_bridge_pvid;
> +
>  	/* In case vlan_filtering_is_global is set, the VLAN awareness state
>  	 * should be retrieved from here and not from the per-port settings.
>  	 */
> diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
> index 5c18c0214aac..dec4ab59b7c4 100644
> --- a/net/dsa/dsa.c
> +++ b/net/dsa/dsa.c
> @@ -225,6 +225,15 @@ static int dsa_switch_rcv(struct sk_buff *skb, struct net_device *dev,
>  	skb->pkt_type = PACKET_HOST;
>  	skb->protocol = eth_type_trans(skb, skb->dev);
>  
> +	if (unlikely(cpu_dp->ds->untag_bridge_pvid)) {
> +		nskb = dsa_untag_bridge_pvid(skb);
> +		if (!nskb) {
> +			kfree_skb(skb);
> +			return 0;
> +		}
> +		skb = nskb;
> +	}
> +
>  	s = this_cpu_ptr(p->stats64);
>  	u64_stats_update_begin(&s->syncp);
>  	s->rx_packets++;
> -- 
> 2.25.1
> 

Re: [PATCH net-next 2/4] net: dsa: b53: Set untag_bridge_pvid

[Vladimir Oltean]

On Thu, Oct 01, 2020 at 07:42:13PM -0700, Florian Fainelli wrote:
> Indicate to the DSA receive path that we need to untage the bridge PVID,
> this allows us to remove the dsa_untag_bridge_pvid() calls from
> net/dsa/tag_brcm.c.
> 
> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
> ---

Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>

>  drivers/net/dsa/b53/b53_common.c |  1 +
>  net/dsa/tag_brcm.c               | 15 ++-------------
>  2 files changed, 3 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/net/dsa/b53/b53_common.c b/drivers/net/dsa/b53/b53_common.c
> index 73507cff3bc4..ce18ba0b74eb 100644
> --- a/drivers/net/dsa/b53/b53_common.c
> +++ b/drivers/net/dsa/b53/b53_common.c
> @@ -2603,6 +2603,7 @@ struct b53_device *b53_switch_alloc(struct device *base,
>  	dev->ops = ops;
>  	ds->ops = &b53_switch_ops;
>  	ds->configure_vlan_while_not_filtering = true;
> +	ds->untag_bridge_pvid = true;
>  	dev->vlan_enabled = ds->configure_vlan_while_not_filtering;
>  	mutex_init(&dev->reg_mutex);
>  	mutex_init(&dev->stats_mutex);
> diff --git a/net/dsa/tag_brcm.c b/net/dsa/tag_brcm.c
> index 69d6b8c597a9..ad72dff8d524 100644
> --- a/net/dsa/tag_brcm.c
> +++ b/net/dsa/tag_brcm.c
> @@ -152,11 +152,6 @@ static struct sk_buff *brcm_tag_rcv_ll(struct sk_buff *skb,
>  	/* Remove Broadcom tag and update checksum */
>  	skb_pull_rcsum(skb, BRCM_TAG_LEN);
>  
> -	/* Set the MAC header to where it should point for
> -	 * dsa_untag_bridge_pvid() to parse the correct VLAN header.
> -	 */
> -	skb_set_mac_header(skb, -ETH_HLEN);
> -
>  	skb->offload_fwd_mark = 1;
>  
>  	return skb;
> @@ -187,7 +182,7 @@ static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
>  		nskb->data - ETH_HLEN - BRCM_TAG_LEN,
>  		2 * ETH_ALEN);
>  
> -	return dsa_untag_bridge_pvid(nskb);
> +	return nskb;
>  }
>  
>  static const struct dsa_device_ops brcm_netdev_ops = {
> @@ -214,14 +209,8 @@ static struct sk_buff *brcm_tag_rcv_prepend(struct sk_buff *skb,
>  					    struct net_device *dev,
>  					    struct packet_type *pt)
>  {
> -	struct sk_buff *nskb;
> -
>  	/* tag is prepended to the packet */
> -	nskb = brcm_tag_rcv_ll(skb, dev, pt, ETH_HLEN);
> -	if (!nskb)
> -		return nskb;
> -
> -	return dsa_untag_bridge_pvid(nskb);
> +	return brcm_tag_rcv_ll(skb, dev, pt, ETH_HLEN);
>  }
>  
>  static const struct dsa_device_ops brcm_prepend_netdev_ops = {
> -- 
> 2.25.1
> 

Re: [PATCH net-next 3/4] net: dsa: Obtain VLAN protocol from skb->protocol

[Vladimir Oltean]

On Thu, Oct 01, 2020 at 07:42:14PM -0700, Florian Fainelli wrote:
> Now that dsa_untag_bridge_pvid() is called after eth_type_trans() we are
> guaranteed that skb->protocol will be set to a correct value, thus
> allowing us to avoid calling vlan_eth_hdr().
> 
> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
> ---

Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>

>  net/dsa/dsa_priv.h | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
> index 0348dbab4131..d6ce8c2a2590 100644
> --- a/net/dsa/dsa_priv.h
> +++ b/net/dsa/dsa_priv.h
> @@ -201,7 +201,6 @@ dsa_slave_to_master(const struct net_device *dev)
>  static inline struct sk_buff *dsa_untag_bridge_pvid(struct sk_buff *skb)
>  {
>  	struct dsa_port *dp = dsa_slave_to_port(skb->dev);
> -	struct vlan_ethhdr *hdr = vlan_eth_hdr(skb);
>  	struct net_device *br = dp->bridge_dev;
>  	struct net_device *dev = skb->dev;
>  	struct net_device *upper_dev;
> @@ -217,7 +216,7 @@ static inline struct sk_buff *dsa_untag_bridge_pvid(struct sk_buff *skb)
>  		return skb;
>  
>  	/* Move VLAN tag from data to hwaccel */
> -	if (!skb_vlan_tag_present(skb) && hdr->h_vlan_proto == htons(proto)) {
> +	if (!skb_vlan_tag_present(skb) && skb->protocol == htons(proto)) {
>  		skb = skb_vlan_untag(skb);
>  		if (!skb)
>  			return NULL;
> -- 
> 2.25.1
> 

Re: [PATCH net-next 4/4] net: dsa: Utilize __vlan_find_dev_deep_rcu()

[Vladimir Oltean]

On Thu, Oct 01, 2020 at 07:42:15PM -0700, Florian Fainelli wrote:
> Now that we are guaranteed that dsa_untag_bridge_pvid() is called after
> eth_type_trans() we can utilize __vlan_find_dev_deep_rcu() which will
> take care of finding an 802.1Q upper on top of a bridge master.
> 
> A common use case, prior to 12a1526d067 ("net: dsa: untag the bridge
> pvid from rx skbs") was to configure a bridge 802.1Q upper like this:
> 
> ip link add name br0 type bridge vlan_filtering 0
> ip link add link br0 name br0.1 type vlan id 1
> 
> in order to pop the default_pvid VLAN tag.
> 
> With this change we restore that behavior while still allowing the DSA
> receive path to automatically pop the VLAN tag.
> 
> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
> ---

Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>

>  net/dsa/dsa_priv.h | 11 +++--------
>  1 file changed, 3 insertions(+), 8 deletions(-)
> 
> diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
> index d6ce8c2a2590..12998bf04e55 100644
> --- a/net/dsa/dsa_priv.h
> +++ b/net/dsa/dsa_priv.h
> @@ -204,7 +204,6 @@ static inline struct sk_buff *dsa_untag_bridge_pvid(struct sk_buff *skb)
>  	struct net_device *br = dp->bridge_dev;
>  	struct net_device *dev = skb->dev;
>  	struct net_device *upper_dev;
> -	struct list_head *iter;
>  	u16 vid, pvid, proto;
>  	int err;
>  
> @@ -246,13 +245,9 @@ static inline struct sk_buff *dsa_untag_bridge_pvid(struct sk_buff *skb)
>  	 * supports because vlan_filtering is 0. In that case, we should
>  	 * definitely keep the tag, to make sure it keeps working.
>  	 */
> -	netdev_for_each_upper_dev_rcu(dev, upper_dev, iter) {
> -		if (!is_vlan_dev(upper_dev))
> -			continue;
> -
> -		if (vid == vlan_dev_vlan_id(upper_dev))
> -			return skb;
> -	}
> +	upper_dev = __vlan_find_dev_deep_rcu(br, htons(proto), vid);
> +	if (upper_dev)
> +		return skb;
>  
>  	__vlan_hwaccel_clear_tag(skb);
>  
> -- 
> 2.25.1
> 

Re: [PATCH net-next 0/4] net: dsa: Improve dsa_untag_bridge_pvid()

[David Miller]

From: Florian Fainelli <f.fainelli@gmail.com>
Date: Thu,  1 Oct 2020 19:42:11 -0700

> Hi David, Jakub,
> 
> This patch series is based on the recent discussions with Vladimir:
> 
> https://lore.kernel.org/netdev/20201001030623.343535-1-f.fainelli@gmail.com/
> 
> the simplest way forward was to call dsa_untag_bridge_pvid() after
> eth_type_trans() has been set which guarantees that skb->protocol is set
> to a correct value and this allows us to utilize
> __vlan_find_dev_deep_rcu() properly without playing or using the bridge
> master as a net_device reference.

Series applied, thanks.