net: build_ehash_secret() and rt_bind_peer() cleanups

Now cmpxchg() is available on all arches, we can use it in
build_ehash_secret() and rt_bind_peer() instead of using spinlocks.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 4 insertions, 13 deletions

diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 6a1100c25a9f..f581f77d1097 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -227,18 +227,16 @@ EXPORT_SYMBOL(inet_ehash_secret);
 
 /*
  * inet_ehash_secret must be set exactly once
- * Instead of using a dedicated spinlock, we (ab)use inetsw_lock
  */
 void build_ehash_secret(void)
 {
         u32 rnd;
+
         do {
                 get_random_bytes(&rnd, sizeof(rnd));
         } while (rnd == 0);
-        spin_lock_bh(&inetsw_lock);
-        if (!inet_ehash_secret)
-                inet_ehash_secret = rnd;
-        spin_unlock_bh(&inetsw_lock);
+
+        cmpxchg(&inet_ehash_secret, 0, rnd);
 }
 EXPORT_SYMBOL(build_ehash_secret);
 
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 3f56b6e6c6aa..85a67c9d5982 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1268,18 +1268,11 @@ skip_hashing:
 
 void rt_bind_peer(struct rtable *rt, int create)
 {
-        static DEFINE_SPINLOCK(rt_peer_lock);
         struct inet_peer *peer;
 
         peer = inet_getpeer(rt->rt_dst, create);
 
-        spin_lock_bh(&rt_peer_lock);
-        if (rt->peer == NULL) {
-                rt->peer = peer;
-                peer = NULL;
-        }
-        spin_unlock_bh(&rt_peer_lock);
-        if (peer)
+        if (peer && cmpxchg(&rt->peer, NULL, peer) != NULL)
                 inet_putpeer(peer);
 }