[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/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 617e858..4ed8a81 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -785,7 +785,7 @@
return err;
}
-struct proto_ops inet_stream_ops = {
+const struct proto_ops inet_stream_ops = {
.family = PF_INET,
.owner = THIS_MODULE,
.release = inet_release,
@@ -806,7 +806,7 @@
.sendpage = tcp_sendpage
};
-struct proto_ops inet_dgram_ops = {
+const struct proto_ops inet_dgram_ops = {
.family = PF_INET,
.owner = THIS_MODULE,
.release = inet_release,
@@ -831,7 +831,7 @@
* For SOCK_RAW sockets; should be the same as inet_dgram_ops but without
* udp_poll
*/
-static struct proto_ops inet_sockraw_ops = {
+static const struct proto_ops inet_sockraw_ops = {
.family = PF_INET,
.owner = THIS_MODULE,
.release = inet_release,