netdev - [PATCH net-next v2] net: bridge: use mld2r_ngrec instead of icmpv6

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Message-Id: <20210829043229.46000-1-shjy180909@gmail.com>
Date:   Sun, 29 Aug 2021 04:32:29 +0000
From:   MichelleJin <shjy180909@...il.com>
To:     davem@...emloft.net, kuba@...nel.org, netdev@...r.kernel.org
Cc:     roopa@...dia.com, nikolay@...dia.com
Subject: [PATCH net-next v2] net: bridge: use mld2r_ngrec instead of icmpv6_dataun

br_ip6_multicast_mld2_report function uses icmp6h 
to parse mld2_report packet.

mld2r_ngrec defines mld2r_hdr.icmp6_dataun.un_data16[1] 
in include/net/mld.h.

So, it is more compact to use mld2r rather than icmp6h.

By doing printk test, it is confirmed that 
icmp6h->icmp6_dataun.un_data16[1] and mld2r->mld2r_ngrec are 
indeed equivalent.

Also, sizeof(*mld2r) and sizeof(*icmp6h) are equivalent, too.

Signed-off-by: MichelleJin <shjy180909@...il.com>
---

v1->v2:
 - change commit message
 - remove unnecesary space after a cast

 net/bridge/br_multicast.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 2c437d4bf632..8e38e02208bd 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -2731,8 +2731,8 @@ static int br_ip6_multicast_mld2_report(struct net_bridge_mcast *brmctx,
 	struct net_bridge_mdb_entry *mdst;
 	struct net_bridge_port_group *pg;
 	unsigned int nsrcs_offset;
+	struct mld2_report *mld2r;
 	const unsigned char *src;
-	struct icmp6hdr *icmp6h;
 	struct in6_addr *h_addr;
 	struct mld2_grec *grec;
 	unsigned int grec_len;
@@ -2740,12 +2740,12 @@ static int br_ip6_multicast_mld2_report(struct net_bridge_mcast *brmctx,
 	int i, len, num;
 	int err = 0;
 
-	if (!ipv6_mc_may_pull(skb, sizeof(*icmp6h)))
+	if (!ipv6_mc_may_pull(skb, sizeof(*mld2r)))
 		return -EINVAL;
 
-	icmp6h = icmp6_hdr(skb);
-	num = ntohs(icmp6h->icmp6_dataun.un_data16[1]);
-	len = skb_transport_offset(skb) + sizeof(*icmp6h);
+	mld2r = (struct mld2_report *)icmp6_hdr(skb);
+	num = ntohs(mld2r->mld2r_ngrec);
+	len = skb_transport_offset(skb) + sizeof(*mld2r);
 
 	for (i = 0; i < num; i++) {
 		__be16 *_nsrcs, __nsrcs;
-- 
2.25.1