[SOCK]: Introduce a percpu inuse counters array (v2).

And redirect sock_prot_inuse_add and _get to use one.

As far as the dereferences are concerned. Before the patch we made
1 dereference to proto->inuse.add call, the call itself and then
called the __get_cpu_var() on a static variable. After the patch we 
make a direct call, then one dereference to proto->inuse_idx and 
then the same __get_cpu_var() on a still static variable. So this 
patch doesn't seem to produce performance penalty on SMP.

This is not per-net yet, but I will deliberately make NET_NS=y case
separated from NET_NS=n one, since it'll cost us one-or-two more 
dereferences to get the struct net and the inuse counter.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 8 deletions

diff --git a/include/net/sock.h b/include/net/sock.h
index abc6341f536..ebf9552664b 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -639,18 +639,15 @@ static inline void sk_refcnt_debug_release(const struct sock *sk)
 # define DEFINE_PROTO_INUSE(NAME) DEFINE_PCOUNTER(NAME)
 # define REF_PROTO_INUSE(NAME) PCOUNTER_MEMBER_INITIALIZER(NAME, .inuse)
 /* Called with local bh disabled */
-static inline void sock_prot_inuse_add(struct proto *prot, int inc)
-{
-	pcounter_add(&prot->inuse, inc);
-}
+extern void sock_prot_inuse_add(struct proto *prot, int inc);
+
 static inline int sock_prot_inuse_init(struct proto *proto)
 {
 	return pcounter_alloc(&proto->inuse);
 }
-static inline int sock_prot_inuse_get(struct proto *proto)
-{
-	return pcounter_getval(&proto->inuse);
-}
+
+extern int sock_prot_inuse_get(struct proto *proto);
+
 static inline void sock_prot_inuse_free(struct proto *proto)
 {
 	pcounter_free(&proto->inuse);