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[NET]: move struct proto_ops to const

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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>
This commit is contained in:
Eric Dumazet
2005-12-22 12:49:22 -08:00
committed by David S. Miller
parent 77d76ea310
commit 90ddc4f047
33 changed files with 66 additions and 66 deletions
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8
net/packet/af_packet.c
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@@ -251,10 +251,10 @@ static void packet_sock_destruct(struct sock *sk)
}
static struct proto_ops packet_ops;
static const struct proto_ops packet_ops;
#ifdef CONFIG_SOCK_PACKET
static struct proto_ops packet_ops_spkt;
static const struct proto_ops packet_ops_spkt;
static int packet_rcv_spkt(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
{
@@ -1784,7 +1784,7 @@ out:
#ifdef CONFIG_SOCK_PACKET
static struct proto_ops packet_ops_spkt = {
static const struct proto_ops packet_ops_spkt = {
.family = PF_PACKET,
.owner = THIS_MODULE,
.release = packet_release,
@@ -1806,7 +1806,7 @@ static struct proto_ops packet_ops_spkt = {
};
#endif
static struct proto_ops packet_ops = {
static const struct proto_ops packet_ops = {
.family = PF_PACKET,
.owner = THIS_MODULE,
.release = packet_release,