[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>
diff --git a/net/key/af_key.c b/net/key/af_key.c
index d32f779..52efd04 100644
--- a/net/key/af_key.c
+++ b/net/key/af_key.c
@@ -113,7 +113,7 @@
}
-static struct proto_ops pfkey_ops;
+static const struct proto_ops pfkey_ops;
static void pfkey_insert(struct sock *sk)
{
@@ -3127,7 +3127,7 @@
return err;
}
-static struct proto_ops pfkey_ops = {
+static const struct proto_ops pfkey_ops = {
.family = PF_KEY,
.owner = THIS_MODULE,
/* Operations that make no sense on pfkey sockets. */