[NET]: move struct proto_ops to const

I noticed that some of 'struct proto_ops' used in the kernel may share
a cache line used by locks or other heavily modified data. (default
linker alignement is 32 bytes, and L1_CACHE_LINE is 64 or 128 at
least)

This patch makes sure a 'struct proto_ops' can be declared as const,
so that all cpus can share all parts of it without false sharing.

This is not mandatory : a driver can still use a read/write structure
if it needs to (and eventually a __read_mostly)

I made a global stubstitute to change all existing occurences to make
them const.

This should reduce the possibility of false sharing on SMP, and
speedup some socket system calls.

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

2 files changed, 2 insertions, 2 deletions

diff --git a/net/atm/pvc.c b/net/atm/pvc.c
index 2684a92da22b..f2c541774dcd 100644
--- a/net/atm/pvc.c
+++ b/net/atm/pvc.c
@@ -102,7 +102,7 @@ static int pvc_getname(struct socket *sock,struct sockaddr *sockaddr,
 }
 
 
-static struct proto_ops pvc_proto_ops = {
+static const struct proto_ops pvc_proto_ops = {
         .family =       PF_ATMPVC,
         .owner =        THIS_MODULE,
 
diff --git a/net/atm/svc.c b/net/atm/svc.c
index d7b266136bf6..3a180cfd7b48 100644
--- a/net/atm/svc.c
+++ b/net/atm/svc.c
@@ -613,7 +613,7 @@ static int svc_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
         return error;
 }
 
-static struct proto_ops svc_proto_ops = {
+static const struct proto_ops svc_proto_ops = {
         .family =       PF_ATMSVC,
         .owner =        THIS_MODULE,