[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/x25/af_x25.c b/net/x25/af_x25.c
index 020d73c..ca8b3b0 100644
--- a/net/x25/af_x25.c
+++ b/net/x25/af_x25.c
@@ -64,7 +64,7 @@
HLIST_HEAD(x25_list);
DEFINE_RWLOCK(x25_list_lock);
-static struct proto_ops x25_proto_ops;
+static const struct proto_ops x25_proto_ops;
static struct x25_address null_x25_address = {" "};
@@ -1391,7 +1391,7 @@
.owner = THIS_MODULE,
};
-static struct proto_ops SOCKOPS_WRAPPED(x25_proto_ops) = {
+static const struct proto_ops SOCKOPS_WRAPPED(x25_proto_ops) = {
.family = AF_X25,
.owner = THIS_MODULE,
.release = x25_release,