[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>

1 files changed, 2 insertions, 2 deletions

diff --git a/include/net/inet_common.h b/include/net/inet_common.h
index f943306ce5ff..227adcbdfec8 100644
--- a/include/net/inet_common.h
+++ b/include/net/inet_common.h
@@ -1,8 +1,8 @@
 #ifndef _INET_COMMON_H
 #define _INET_COMMON_H
 
-extern struct proto_ops         inet_stream_ops;
-extern struct proto_ops         inet_dgram_ops;
+extern const struct proto_ops           inet_stream_ops;
+extern const struct proto_ops           inet_dgram_ops;
 
 /*
  *      INET4 prototypes used by INET6