[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/llc/af_llc.c b/net/llc/af_llc.c
index b6d3df5..9cf65f9 100644
--- a/net/llc/af_llc.c
+++ b/net/llc/af_llc.c
@@ -36,7 +36,7 @@
static u16 llc_ui_sap_last_autoport = LLC_SAP_DYN_START;
static u16 llc_ui_sap_link_no_max[256];
static struct sockaddr_llc llc_ui_addrnull;
-static struct proto_ops llc_ui_ops;
+static const struct proto_ops llc_ui_ops;
static int llc_ui_wait_for_conn(struct sock *sk, long timeout);
static int llc_ui_wait_for_disc(struct sock *sk, long timeout);
@@ -1098,7 +1098,7 @@
.owner = THIS_MODULE,
};
-static struct proto_ops llc_ui_ops = {
+static const struct proto_ops llc_ui_ops = {
.family = PF_LLC,
.owner = THIS_MODULE,
.release = llc_ui_release,