net: udp_unhash() can test if sk is hashed

Impact: Optimization

Like done in inet_unhash(), we can avoid taking a chain lock if
socket is not hashed in udp_unhash()

Triggered by close(socket(AF_INET, SOCK_DGRAM, 0));

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 8 deletions

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 549114472db3..cf5ab0581eba 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -970,16 +970,18 @@ int udp_disconnect(struct sock *sk, int flags)
 
 void udp_lib_unhash(struct sock *sk)
 {
-        struct udp_table *udptable = sk->sk_prot->h.udp_table;
-        unsigned int hash = udp_hashfn(sock_net(sk), sk->sk_hash);
-        struct udp_hslot *hslot = &udptable->hash[hash];
+        if (sk_hashed(sk)) {
+                struct udp_table *udptable = sk->sk_prot->h.udp_table;
+                unsigned int hash = udp_hashfn(sock_net(sk), sk->sk_hash);
+                struct udp_hslot *hslot = &udptable->hash[hash];
 
-        spin_lock_bh(&hslot->lock);
-        if (sk_nulls_del_node_init_rcu(sk)) {
-                inet_sk(sk)->num = 0;
-                sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
+                spin_lock_bh(&hslot->lock);
+                if (sk_nulls_del_node_init_rcu(sk)) {
+                        inet_sk(sk)->num = 0;
+                        sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
+                }
+                spin_unlock_bh(&hslot->lock);
         }
-        spin_unlock_bh(&hslot->lock);
 }
 EXPORT_SYMBOL(udp_lib_unhash);