net: Use a percpu_counter for sockets_allocated

Instead of using one atomic_t per protocol, use a percpu_counter
for "sockets_allocated", to reduce cache line contention on
heavy duty network servers. 

Note : We revert commit (248969ae31e1b3276fc4399d67ce29a5d81e6fd9
net: af_unix can make unix_nr_socks visbile in /proc),
since it is not anymore used after sock_prot_inuse_add() addition

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

1 files changed, 5 insertions, 1 deletions

diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index a8ca743241ee..d5ea232c9126 100644
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -102,6 +102,8 @@ struct sock *sctp_get_ctl_sock(void)
 /* Set up the proc fs entry for the SCTP protocol. */
 static __init int sctp_proc_init(void)
 {
+        if (percpu_counter_init(&sctp_sockets_allocated, 0))
+                goto out_nomem;
 #ifdef CONFIG_PROC_FS
         if (!proc_net_sctp) {
                 struct proc_dir_entry *ent;
@@ -110,7 +112,7 @@ static __init int sctp_proc_init(void)
                         ent->owner = THIS_MODULE;
                         proc_net_sctp = ent;
                 } else
-                        goto out_nomem;
+                        goto out_free_percpu;
         }
 
         if (sctp_snmp_proc_init())
@@ -135,6 +137,8 @@ out_snmp_proc_init:
                 proc_net_sctp = NULL;
                 remove_proc_entry("sctp", init_net.proc_net);
         }
+out_free_percpu:
+        percpu_counter_destroy(&sctp_sockets_allocated);
 out_nomem:
         return -ENOMEM;
 #else