Commit b81aa232 authored Aug 26, 2025 by Eric Dumazet Committed by Paolo Abeni Aug 28, 2025

inet: raw: add drop_counters to raw sockets



When a packet flood hits one or more RAW sockets, many cpus
have to update sk->sk_drops.

This slows down other cpus, because currently
sk_drops is in sock_write_rx group.

Add a socket_drop_counters structure to raw sockets.

Using dedicated cache lines to hold drop counters
makes sure that consumers no longer suffer from
false sharing if/when producers only change sk->sk_drops.

This adds 128 bytes per RAW socket.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20250826125031.1578842-6-edumazet@google.com


Signed-off-by: Paolo Abeni <pabeni@redhat.com>

parent 51132b99

include/linux/ipv6.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -295,7 +295,7 @@ struct raw6_sock {
		__u32 offset; /* checksum offset */
		struct icmp6_filter filter;
		__u32 ip6mr_table;

		struct socket_drop_counters drop_counters;
		struct ipv6_pinfo inet6;
		};

include/net/raw.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -81,6 +81,7 @@ struct raw_sock {
		struct inet_sock inet;
		struct icmp_filter filter;
		u32 ipmr_table;
		struct socket_drop_counters drop_counters;
		};

		#define raw_sk(ptr) container_of_const(ptr, struct raw_sock, inet.sk)

net/ipv4/raw.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -793,6 +793,7 @@ static int raw_sk_init(struct sock *sk)
		{
		struct raw_sock *rp = raw_sk(sk);

		sk->sk_drop_counters = &rp->drop_counters;
		if (inet_sk(sk)->inet_num == IPPROTO_ICMP)
		memset(&rp->filter, 0, sizeof(rp->filter));
		return 0;

net/ipv6/raw.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -1175,6 +1175,7 @@ static int rawv6_init_sk(struct sock *sk)
		{
		struct raw6_sock *rp = raw6_sk(sk);

		sk->sk_drop_counters = &rp->drop_counters;
		switch (inet_sk(sk)->inet_num) {
		case IPPROTO_ICMPV6:
		rp->checksum = 1;