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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Wed, 31 Aug 2016 17:54:09 +0200
Subject: [PATCH 203/353] net: add a lock around icmp_sk()
Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=c532906af442e35a3dd02bf538c432102b50cc63
It looks like the this_cpu_ptr() access in icmp_sk() is protected with
local_bh_disable(). To avoid missing serialization in -RT I am adding
here a local lock. No crash has been observed, this is just precaution.
Cc: stable-rt@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
net/ipv4/icmp.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index af0ddaa55e43..cadaf93f5614 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -77,6 +77,7 @@
#include <linux/string.h>
#include <linux/netfilter_ipv4.h>
#include <linux/slab.h>
+#include <linux/locallock.h>
#include <net/snmp.h>
#include <net/ip.h>
#include <net/route.h>
@@ -204,6 +205,8 @@ static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
*
* On SMP we have one ICMP socket per-cpu.
*/
+static DEFINE_LOCAL_IRQ_LOCK(icmp_sk_lock);
+
static struct sock *icmp_sk(struct net *net)
{
return *this_cpu_ptr(net->ipv4.icmp_sk);
@@ -214,12 +217,16 @@ static inline struct sock *icmp_xmit_lock(struct net *net)
{
struct sock *sk;
+ if (!local_trylock(icmp_sk_lock))
+ return NULL;
+
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_unlock(icmp_sk_lock);
return NULL;
}
return sk;
@@ -228,6 +235,7 @@ static inline struct sock *icmp_xmit_lock(struct net *net)
static inline void icmp_xmit_unlock(struct sock *sk)
{
spin_unlock(&sk->sk_lock.slock);
+ local_unlock(icmp_sk_lock);
}
int sysctl_icmp_msgs_per_sec __read_mostly = 1000;
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