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authorJesper Dangaard Brouer <brouer@redhat.com>2017-01-09 16:04:14 +0100
committerDavid S. Miller <davem@davemloft.net>2017-01-09 15:49:12 -0500
commit7ba91ecb16824f74ba4fcbc4e88cd4d24a839b25 (patch)
tree23bd866126b5115cf4a14541f7700117a38efc29 /net/ipv4/icmp.c
parentc0303efeab7391ec51c337e0ac5740860ad01fe7 (diff)
net: for rate-limited ICMP replies save one atomic operation
It is possible to avoid the atomic operation in icmp{v6,}_xmit_lock, by checking the sysctl_icmp_msgs_per_sec ratelimit before these calls, as pointed out by Eric Dumazet, but the BH disabled state must be correct. The icmp_global_allow() call states it must be called with BH disabled. This protection was given by the calls icmp_xmit_lock and icmpv6_xmit_lock. Thus, split out local_bh_disable/enable from these functions and maintain it explicitly at callers. Suggested-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/icmp.c')
-rw-r--r--net/ipv4/icmp.c34
1 files changed, 21 insertions, 13 deletions
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index 58d75ca58b83..fc310db2708b 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -209,19 +209,17 @@ static struct sock *icmp_sk(struct net *net)
return *this_cpu_ptr(net->ipv4.icmp_sk);
}
+/* Called with BH disabled */
static inline struct sock *icmp_xmit_lock(struct net *net)
{
struct sock *sk;
- local_bh_disable();
-
sk = icmp_sk(net);
if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
/* This can happen if the output path signals a
* dst_link_failure() for an outgoing ICMP packet.
*/
- local_bh_enable();
return NULL;
}
return sk;
@@ -229,7 +227,7 @@ static inline struct sock *icmp_xmit_lock(struct net *net)
static inline void icmp_xmit_unlock(struct sock *sk)
{
- spin_unlock_bh(&sk->sk_lock.slock);
+ spin_unlock(&sk->sk_lock.slock);
}
int sysctl_icmp_msgs_per_sec __read_mostly = 1000;
@@ -417,14 +415,17 @@ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb))
return;
- sk = icmp_xmit_lock(net);
- if (!sk)
- return;
- inet = inet_sk(sk);
+ /* Needed by both icmp_global_allow and icmp_xmit_lock */
+ local_bh_disable();
/* global icmp_msgs_per_sec */
if (!icmpv4_global_allow(net, type, code))
- goto out_unlock;
+ goto out_bh_enable;
+
+ sk = icmp_xmit_lock(net);
+ if (!sk)
+ goto out_bh_enable;
+ inet = inet_sk(sk);
icmp_param->data.icmph.checksum = 0;
@@ -459,6 +460,8 @@ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
ip_rt_put(rt);
out_unlock:
icmp_xmit_unlock(sk);
+out_bh_enable:
+ local_bh_enable();
}
#ifdef CONFIG_IP_ROUTE_MULTIPATH
@@ -668,13 +671,16 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
}
}
- sk = icmp_xmit_lock(net);
- if (!sk)
- goto out;
+ /* Needed by both icmp_global_allow and icmp_xmit_lock */
+ local_bh_disable();
/* Check global sysctl_icmp_msgs_per_sec ratelimit */
if (!icmpv4_global_allow(net, type, code))
- goto out_unlock;
+ goto out_bh_enable;
+
+ sk = icmp_xmit_lock(net);
+ if (!sk)
+ goto out_bh_enable;
/*
* Construct source address and options.
@@ -750,6 +756,8 @@ ende:
ip_rt_put(rt);
out_unlock:
icmp_xmit_unlock(sk);
+out_bh_enable:
+ local_bh_enable();
out:;
}
EXPORT_SYMBOL(icmp_send);