[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/include/linux/net.h b/include/linux/net.h
index d6a41e6..28195a2 100644
--- a/include/linux/net.h
+++ b/include/linux/net.h
@@ -107,7 +107,7 @@
struct socket {
socket_state state;
unsigned long flags;
- struct proto_ops *ops;
+ const struct proto_ops *ops;
struct fasync_struct *fasync_list;
struct file *file;
struct sock *sk;
@@ -260,7 +260,7 @@
SOCKCALL_WRAP(name, mmap, (struct file *file, struct socket *sock, struct vm_area_struct *vma), \
(file, sock, vma)) \
\
-static struct proto_ops name##_ops = { \
+static const struct proto_ops name##_ops = { \
.family = fam, \
.owner = THIS_MODULE, \
.release = __lock_##name##_release, \