[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/unix/af_unix.c b/net/unix/af_unix.c
index 04e850e..7d3fe6a 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -473,7 +473,7 @@
static int unix_seqpacket_sendmsg(struct kiocb *, struct socket *,
struct msghdr *, size_t);
-static struct proto_ops unix_stream_ops = {
+static const struct proto_ops unix_stream_ops = {
.family = PF_UNIX,
.owner = THIS_MODULE,
.release = unix_release,
@@ -494,7 +494,7 @@
.sendpage = sock_no_sendpage,
};
-static struct proto_ops unix_dgram_ops = {
+static const struct proto_ops unix_dgram_ops = {
.family = PF_UNIX,
.owner = THIS_MODULE,
.release = unix_release,
@@ -515,7 +515,7 @@
.sendpage = sock_no_sendpage,
};
-static struct proto_ops unix_seqpacket_ops = {
+static const struct proto_ops unix_seqpacket_ops = {
.family = PF_UNIX,
.owner = THIS_MODULE,
.release = unix_release,