Re: [PATCH net-next RESEND] net: bonding: add bond_is_icmpv6_nd() helper

[Jay Vosburgh <jv@jvosburgh.net>]

Tonghao Zhang <tonghao@bamaicloud.com> wrote:

>Introduce ipv6 ns/nd checking helper, using skb_header_pointer()
>instead of pskb_network_may_pull() on tx path.
>
>alb_determine_nd introduced from commit 0da8aa00bfcfe
>
>Cc: Jay Vosburgh <jv@jvosburgh.net>
>Cc: "David S. Miller" <davem@davemloft.net>
>Cc: Eric Dumazet <edumazet@google.com>
>Cc: Jakub Kicinski <kuba@kernel.org>
>Cc: Paolo Abeni <pabeni@redhat.com>
>Cc: Simon Horman <horms@kernel.org>
>Cc: Jonathan Corbet <corbet@lwn.net>
>Cc: Andrew Lunn <andrew+netdev@lunn.ch>
>Cc: Nikolay Aleksandrov <razor@blackwall.org>
>Signed-off-by: Tonghao Zhang <tonghao@bamaicloud.com>
>Signed-off-by: Zengbing Tu <tuzengbing@didiglobal.com>
>---
> drivers/net/bonding/bond_alb.c  | 32 +++++++-------------------------
> drivers/net/bonding/bond_main.c | 17 ++---------------
> include/net/bonding.h           | 19 +++++++++++++++++++
> 3 files changed, 28 insertions(+), 40 deletions(-)
>
>diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c
>index 2d37b07c8215..8e5b9ce52077 100644
>--- a/drivers/net/bonding/bond_alb.c
>+++ b/drivers/net/bonding/bond_alb.c
>@@ -19,7 +19,6 @@
> #include <linux/in.h>
> #include <net/arp.h>
> #include <net/ipv6.h>
>-#include <net/ndisc.h>
> #include <asm/byteorder.h>
> #include <net/bonding.h>
> #include <net/bond_alb.h>
>@@ -1280,27 +1279,6 @@ static int alb_set_mac_address(struct bonding *bond, void *addr)
> 	return res;
> }
> 
>-/* determine if the packet is NA or NS */
>-static bool alb_determine_nd(struct sk_buff *skb, struct bonding *bond)
>-{
>-	struct ipv6hdr *ip6hdr;
>-	struct icmp6hdr *hdr;
>-
>-	if (!pskb_network_may_pull(skb, sizeof(*ip6hdr)))
>-		return true;
>-
>-	ip6hdr = ipv6_hdr(skb);
>-	if (ip6hdr->nexthdr != IPPROTO_ICMPV6)
>-		return false;
>-
>-	if (!pskb_network_may_pull(skb, sizeof(*ip6hdr) + sizeof(*hdr)))
>-		return true;
>-
>-	hdr = icmp6_hdr(skb);
>-	return hdr->icmp6_type == NDISC_NEIGHBOUR_ADVERTISEMENT ||
>-		hdr->icmp6_type == NDISC_NEIGHBOUR_SOLICITATION;
>-}
>-
> /************************ exported alb functions ************************/
> 
> int bond_alb_initialize(struct bonding *bond, int rlb_enabled)
>@@ -1381,7 +1359,7 @@ struct slave *bond_xmit_tlb_slave_get(struct bonding *bond,
> 	if (!is_multicast_ether_addr(eth_data->h_dest)) {
> 		switch (skb->protocol) {
> 		case htons(ETH_P_IPV6):
>-			if (alb_determine_nd(skb, bond))
>+			if (bond_is_icmpv6_nd(skb))
> 				break;
> 			fallthrough;
> 		case htons(ETH_P_IP):
>@@ -1467,16 +1445,20 @@ struct slave *bond_xmit_alb_slave_get(struct bonding *bond,
> 			break;
> 		}
> 
>-		if (alb_determine_nd(skb, bond)) {
>+		if (bond_is_icmpv6_nd(skb)) {
> 			do_tx_balance = false;
> 			break;
> 		}
> 
>-		/* The IPv6 header is pulled by alb_determine_nd */
> 		/* Additionally, DAD probes should not be tx-balanced as that
> 		 * will lead to false positives for duplicate addresses and
> 		 * prevent address configuration from working.
> 		 */
>+		if (!pskb_network_may_pull(skb, sizeof(*ip6hdr))) {
>+			do_tx_balance = false;
>+			break;
>+		}
>+

	It's nice to consolidate some duplicate code and use the more
efficient skb_header_pointer, but the above will do a pull anyway for
nearly every packet that passed through the function.

	Would it be better to not use the bond_is_icmpv6_nd helper here,
but instead call skb_header_pointer directly, and then reuse its
returned data for the hash computation that occurs just after this point
in the code?

> 		ip6hdr = ipv6_hdr(skb);
> 		if (ipv6_addr_any(&ip6hdr->saddr)) {
> 			do_tx_balance = false;
>diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>index 17c7542be6a5..a8034a561011 100644
>--- a/drivers/net/bonding/bond_main.c
>+++ b/drivers/net/bonding/bond_main.c
>@@ -5338,10 +5338,6 @@ static bool bond_should_broadcast_neighbor(struct sk_buff *skb,
> 					   struct net_device *dev)
> {
> 	struct bonding *bond = netdev_priv(dev);
>-	struct {
>-		struct ipv6hdr ip6;
>-		struct icmp6hdr icmp6;
>-	} *combined, _combined;
> 
> 	if (!static_branch_unlikely(&bond_bcast_neigh_enabled))
> 		return false;
>@@ -5349,19 +5345,10 @@ static bool bond_should_broadcast_neighbor(struct sk_buff *skb,
> 	if (!bond->params.broadcast_neighbor)
> 		return false;
> 
>-	if (skb->protocol == htons(ETH_P_ARP))
>+	if (skb->protocol == htons(ETH_P_ARP) ||
>+	    (skb->protocol == htons(ETH_P_IPV6) && bond_is_icmpv6_nd(skb)))
> 		return true;
> 
>-	if (skb->protocol == htons(ETH_P_IPV6)) {
>-		combined = skb_header_pointer(skb, skb_mac_header_len(skb),
>-					      sizeof(_combined),
>-					      &_combined);
>-		if (combined && combined->ip6.nexthdr == NEXTHDR_ICMP &&
>-		    (combined->icmp6.icmp6_type == NDISC_NEIGHBOUR_SOLICITATION ||
>-		     combined->icmp6.icmp6_type == NDISC_NEIGHBOUR_ADVERTISEMENT))
>-			return true;
>-	}
>-
> 	return false;
> }
> 
>diff --git a/include/net/bonding.h b/include/net/bonding.h
>index e06f0d63b2c1..32d9fcca858c 100644
>--- a/include/net/bonding.h
>+++ b/include/net/bonding.h
>@@ -29,6 +29,7 @@
> #include <net/bond_options.h>
> #include <net/ipv6.h>
> #include <net/addrconf.h>
>+#include <net/ndisc.h>
> 
> #define BOND_MAX_ARP_TARGETS	16
> #define BOND_MAX_NS_TARGETS	BOND_MAX_ARP_TARGETS
>@@ -814,4 +815,22 @@ static inline netdev_tx_t bond_tx_drop(struct net_device *dev, struct sk_buff *s
> 	return NET_XMIT_DROP;
> }
> 
>+static inline bool bond_is_icmpv6_nd(struct sk_buff *skb)
>+{

	Minor nit: no need to specify inline, the compiler will decide.

	-J

>+	struct {
>+		struct ipv6hdr ip6;
>+		struct icmp6hdr icmp6;
>+	} *combined, _combined;
>+
>+	combined = skb_header_pointer(skb, skb_mac_header_len(skb),
>+				      sizeof(_combined),
>+				      &_combined);
>+	if (combined && combined->ip6.nexthdr == NEXTHDR_ICMP &&
>+	    (combined->icmp6.icmp6_type == NDISC_NEIGHBOUR_SOLICITATION ||
>+	     combined->icmp6.icmp6_type == NDISC_NEIGHBOUR_ADVERTISEMENT))
>+		return true;
>+
>+	return false;
>+}
>+
> #endif /* _NET_BONDING_H */
>-- 
>2.34.1
>

---
	-Jay Vosburgh, jv@jvosburgh.net