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[NETFILTER] CLUSTERIP: use a bitmap to store node responsibility data
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Instead of maintaining an array containing a list of nodes this instance
is responsible for let's use a simple bitmap. This provides the
following features:

  * clusterip_responsible() and the add_node()/delete_node() operations
    become very simple and don't need locking
  * the config structure is much smaller

In spite of the completely different internal data representation the
user-space interface remains almost unchanged; the only difference is
that the proc file does not list nodes in the order they were added.
(The target info structure remains the same.)

Signed-off-by: KOVACS Krisztian <hidden@balabit.hu>
Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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@davem330
KOVACS Krisztian authored and davem330 committed Sep 17, 2005
1 parent 4451362 commit 136e92b
Showing 1 changed file with 61 additions and 82 deletions.
143 changes: 61 additions & 82 deletions net/ipv4/netfilter/ipt_CLUSTERIP.c
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@
#include <linux/config.h>
#include <linux/proc_fs.h>
#include <linux/jhash.h>
#include <linux/bitops.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <linux/tcp.h>
Expand All @@ -30,7 +31,7 @@
#include <linux/netfilter_ipv4/ipt_CLUSTERIP.h>
#include <linux/netfilter_ipv4/ip_conntrack.h>

#define CLUSTERIP_VERSION "0.7"
#define CLUSTERIP_VERSION "0.8"

#define DEBUG_CLUSTERIP

Expand All @@ -56,8 +57,7 @@ struct clusterip_config {
u_int8_t clustermac[ETH_ALEN]; /* the MAC address */
struct net_device *dev; /* device */
u_int16_t num_total_nodes; /* total number of nodes */
u_int16_t num_local_nodes; /* number of local nodes */
u_int16_t local_nodes[CLUSTERIP_MAX_NODES]; /* node number array */
unsigned long local_nodes; /* node number array */

#ifdef CONFIG_PROC_FS
struct proc_dir_entry *pde; /* proc dir entry */
Expand All @@ -68,8 +68,7 @@ struct clusterip_config {

static LIST_HEAD(clusterip_configs);

/* clusterip_lock protects the clusterip_configs list _AND_ the configurable
* data within all structurses (num_local_nodes, local_nodes[]) */
/* clusterip_lock protects the clusterip_configs list */
static DEFINE_RWLOCK(clusterip_lock);

#ifdef CONFIG_PROC_FS
Expand Down Expand Up @@ -156,6 +155,17 @@ clusterip_config_find_get(u_int32_t clusterip, int entry)
return c;
}

static void
clusterip_config_init_nodelist(struct clusterip_config *c,
const struct ipt_clusterip_tgt_info *i)
{
int n;

for (n = 0; n < i->num_local_nodes; n++) {
set_bit(i->local_nodes[n] - 1, &c->local_nodes);
}
}

static struct clusterip_config *
clusterip_config_init(struct ipt_clusterip_tgt_info *i, u_int32_t ip,
struct net_device *dev)
Expand All @@ -172,8 +182,7 @@ clusterip_config_init(struct ipt_clusterip_tgt_info *i, u_int32_t ip,
c->clusterip = ip;
memcpy(&c->clustermac, &i->clustermac, ETH_ALEN);
c->num_total_nodes = i->num_total_nodes;
c->num_local_nodes = i->num_local_nodes;
memcpy(&c->local_nodes, &i->local_nodes, sizeof(c->local_nodes));
clusterip_config_init_nodelist(c, i);
c->hash_mode = i->hash_mode;
c->hash_initval = i->hash_initval;
atomic_set(&c->refcount, 1);
Expand Down Expand Up @@ -201,53 +210,28 @@ clusterip_config_init(struct ipt_clusterip_tgt_info *i, u_int32_t ip,
static int
clusterip_add_node(struct clusterip_config *c, u_int16_t nodenum)
{
int i;

write_lock_bh(&clusterip_lock);

if (c->num_local_nodes >= CLUSTERIP_MAX_NODES
|| nodenum > CLUSTERIP_MAX_NODES) {
write_unlock_bh(&clusterip_lock);
if (nodenum == 0 ||
nodenum > c->num_total_nodes)
return 1;
}

/* check if we alrady have this number in our array */
for (i = 0; i < c->num_local_nodes; i++) {
if (c->local_nodes[i] == nodenum) {
write_unlock_bh(&clusterip_lock);
return 1;
}
}

c->local_nodes[c->num_local_nodes++] = nodenum;
/* check if we already have this number in our bitfield */
if (test_and_set_bit(nodenum - 1, &c->local_nodes))
return 1;

write_unlock_bh(&clusterip_lock);
return 0;
}

static int
clusterip_del_node(struct clusterip_config *c, u_int16_t nodenum)
{
int i;

write_lock_bh(&clusterip_lock);

if (c->num_local_nodes <= 1 || nodenum > CLUSTERIP_MAX_NODES) {
write_unlock_bh(&clusterip_lock);
if (nodenum == 0 ||
nodenum > c->num_total_nodes)
return 1;
}

for (i = 0; i < c->num_local_nodes; i++) {
if (c->local_nodes[i] == nodenum) {
int size = sizeof(u_int16_t)*(c->num_local_nodes-(i+1));
memmove(&c->local_nodes[i], &c->local_nodes[i+1], size);
c->num_local_nodes--;
write_unlock_bh(&clusterip_lock);
return 0;
}
}
if (test_and_clear_bit(nodenum - 1, &c->local_nodes))
return 0;

write_unlock_bh(&clusterip_lock);
return 1;
}

Expand Down Expand Up @@ -315,25 +299,7 @@ clusterip_hashfn(struct sk_buff *skb, struct clusterip_config *config)
static inline int
clusterip_responsible(struct clusterip_config *config, u_int32_t hash)
{
int i;

read_lock_bh(&clusterip_lock);

if (config->num_local_nodes == 0) {
read_unlock_bh(&clusterip_lock);
return 0;
}

for (i = 0; i < config->num_local_nodes; i++) {
if (config->local_nodes[i] == hash) {
read_unlock_bh(&clusterip_lock);
return 1;
}
}

read_unlock_bh(&clusterip_lock);

return 0;
return test_bit(hash - 1, &config->local_nodes);
}

/***********************************************************************
Expand Down Expand Up @@ -618,56 +584,69 @@ static struct nf_hook_ops cip_arp_ops = {

#ifdef CONFIG_PROC_FS

struct clusterip_seq_position {
unsigned int pos; /* position */
unsigned int weight; /* number of bits set == size */
unsigned int bit; /* current bit */
unsigned long val; /* current value */
};

static void *clusterip_seq_start(struct seq_file *s, loff_t *pos)
{
struct proc_dir_entry *pde = s->private;
struct clusterip_config *c = pde->data;
unsigned int *nodeidx;

read_lock_bh(&clusterip_lock);
if (*pos >= c->num_local_nodes)
unsigned int weight;
u_int32_t local_nodes;
struct clusterip_seq_position *idx;

/* FIXME: possible race */
local_nodes = c->local_nodes;
weight = hweight32(local_nodes);
if (*pos >= weight)
return NULL;

nodeidx = kmalloc(sizeof(unsigned int), GFP_KERNEL);
if (!nodeidx)
idx = kmalloc(sizeof(struct clusterip_seq_position), GFP_KERNEL);
if (!idx)
return ERR_PTR(-ENOMEM);

*nodeidx = *pos;
return nodeidx;
idx->pos = *pos;
idx->weight = weight;
idx->bit = ffs(local_nodes);
idx->val = local_nodes;
clear_bit(idx->bit - 1, &idx->val);

return idx;
}

static void *clusterip_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
struct proc_dir_entry *pde = s->private;
struct clusterip_config *c = pde->data;
unsigned int *nodeidx = (unsigned int *)v;
struct clusterip_seq_position *idx = (struct clusterip_seq_position *)v;

*pos = ++(*nodeidx);
if (*pos >= c->num_local_nodes) {
*pos = ++idx->pos;
if (*pos >= idx->weight) {
kfree(v);
return NULL;
}
return nodeidx;
idx->bit = ffs(idx->val);
clear_bit(idx->bit - 1, &idx->val);
return idx;
}

static void clusterip_seq_stop(struct seq_file *s, void *v)
{
kfree(v);

read_unlock_bh(&clusterip_lock);
}

static int clusterip_seq_show(struct seq_file *s, void *v)
{
struct proc_dir_entry *pde = s->private;
struct clusterip_config *c = pde->data;
unsigned int *nodeidx = (unsigned int *)v;
struct clusterip_seq_position *idx = (struct clusterip_seq_position *)v;

if (*nodeidx != 0)
if (idx->pos != 0)
seq_putc(s, ',');
seq_printf(s, "%u", c->local_nodes[*nodeidx]);

if (*nodeidx == c->num_local_nodes-1)
seq_printf(s, "%u", idx->bit);

if (idx->pos == idx->weight - 1)
seq_putc(s, '\n');

return 0;
Expand Down

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