[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/ipx/af_ipx.c b/net/ipx/af_ipx.c
index 34b3bb8..6c464c1 100644
--- a/net/ipx/af_ipx.c
+++ b/net/ipx/af_ipx.c
@@ -75,7 +75,7 @@
static struct datalink_proto *p8023_datalink;
static struct datalink_proto *pSNAP_datalink;
-static struct proto_ops ipx_dgram_ops;
+static const struct proto_ops ipx_dgram_ops;
LIST_HEAD(ipx_interfaces);
DEFINE_SPINLOCK(ipx_interfaces_lock);
@@ -1901,7 +1901,7 @@
.owner = THIS_MODULE,
};
-static struct proto_ops SOCKOPS_WRAPPED(ipx_dgram_ops) = {
+static const struct proto_ops SOCKOPS_WRAPPED(ipx_dgram_ops) = {
.family = PF_IPX,
.owner = THIS_MODULE,
.release = ipx_release,