[PATCH] IPVS: Allow boot time change of hash size.

["Catalin(ux) M. BOIE" <catab@embedromix.ro>]

I was very frustrated about the fact that I have to recompile the kernel
to change the hash size. So, I created this patch.
If IPVS is built-in you can append ip_vs.conn_tab_bits=?? to kernel
command line, or, if you built IPVS as modules, you can add
options ip_vs conn_tab_bits=??.
To keep everything backward compatible, you still can select the size at
compile time, and that will be used as default.

Signed-off-by: Catalin(ux) M. BOIE <catab@embedromix.ro>
---
 include/net/ip_vs.h             |   16 ++++----------
 net/netfilter/ipvs/Kconfig      |    4 +++
 net/netfilter/ipvs/ip_vs_conn.c |   41 ++++++++++++++++++++++++++++----------
 net/netfilter/ipvs/ip_vs_ctl.c  |    8 +++---
 4 files changed, 43 insertions(+), 26 deletions(-)

diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
index fe9fcf7..5a788a4 100644
--- a/include/net/ip_vs.h
+++ b/include/net/ip_vs.h
@@ -26,6 +26,11 @@
 #include <linux/ipv6.h>			/* for struct ipv6hdr */
 #include <net/ipv6.h>			/* for ipv6_addr_copy */
 
+
+/* Connections' size value needed by ip_vs_ctl.c */
+extern int ip_vs_conn_tab_size;
+
+
 struct ip_vs_iphdr {
 	int len;
 	__u8 protocol;
@@ -599,17 +604,6 @@ extern void ip_vs_init_hash_table(struct list_head *table, int rows);
  *     (from ip_vs_conn.c)
  */
 
-/*
- *     IPVS connection entry hash table
- */
-#ifndef CONFIG_IP_VS_TAB_BITS
-#define CONFIG_IP_VS_TAB_BITS   12
-#endif
-
-#define IP_VS_CONN_TAB_BITS	CONFIG_IP_VS_TAB_BITS
-#define IP_VS_CONN_TAB_SIZE     (1 << IP_VS_CONN_TAB_BITS)
-#define IP_VS_CONN_TAB_MASK     (IP_VS_CONN_TAB_SIZE - 1)
-
 enum {
 	IP_VS_DIR_INPUT = 0,
 	IP_VS_DIR_OUTPUT,
diff --git a/net/netfilter/ipvs/Kconfig b/net/netfilter/ipvs/Kconfig
index 79a6980..c71e543 100644
--- a/net/netfilter/ipvs/Kconfig
+++ b/net/netfilter/ipvs/Kconfig
@@ -68,6 +68,10 @@ config	IP_VS_TAB_BITS
 	  each hash entry uses 8 bytes, so you can estimate how much memory is
 	  needed for your box.
 
+	  You can overwrite this number setting conn_tab_bits module parameter
+	  or by appending ip_vs.conn_tab_bits=? to the kernel command line
+	  if IP VS was compiled built-in.
+
 comment "IPVS transport protocol load balancing support"
 
 config	IP_VS_PROTO_TCP
diff --git a/net/netfilter/ipvs/ip_vs_conn.c b/net/netfilter/ipvs/ip_vs_conn.c
index 9a24332..b1462f1 100644
--- a/net/netfilter/ipvs/ip_vs_conn.c
+++ b/net/netfilter/ipvs/ip_vs_conn.c
@@ -37,6 +37,21 @@
 #include <net/ip_vs.h>
 
 
+#ifndef CONFIG_IP_VS_TAB_BITS
+#define CONFIG_IP_VS_TAB_BITS	12
+#endif
+
+/*
+ * Connection hash size. Default is what was selected at compile time.
+*/
+int ip_vs_conn_tab_bits = CONFIG_IP_VS_TAB_BITS;
+module_param_named(conn_tab_bits, ip_vs_conn_tab_bits, int, 0444);
+MODULE_PARM_DESC(conn_tab_bits, "Set connections' hash size");
+
+/* size and mask values */
+int ip_vs_conn_tab_size;
+int ip_vs_conn_tab_mask;
+
 /*
  *  Connection hash table: for input and output packets lookups of IPVS
  */
@@ -122,11 +137,11 @@ static unsigned int ip_vs_conn_hashkey(int af, unsigned proto,
 	if (af == AF_INET6)
 		return jhash_3words(jhash(addr, 16, ip_vs_conn_rnd),
 				    (__force u32)port, proto, ip_vs_conn_rnd)
-			& IP_VS_CONN_TAB_MASK;
+			& ip_vs_conn_tab_mask;
 #endif
 	return jhash_3words((__force u32)addr->ip, (__force u32)port, proto,
 			    ip_vs_conn_rnd)
-		& IP_VS_CONN_TAB_MASK;
+		& ip_vs_conn_tab_mask;
 }
 
 
@@ -752,7 +767,7 @@ static void *ip_vs_conn_array(struct seq_file *seq, loff_t pos)
 	int idx;
 	struct ip_vs_conn *cp;
 
-	for(idx = 0; idx < IP_VS_CONN_TAB_SIZE; idx++) {
+	for(idx = 0; idx < ip_vs_conn_tab_size; idx++) {
 		ct_read_lock_bh(idx);
 		list_for_each_entry(cp, &ip_vs_conn_tab[idx], c_list) {
 			if (pos-- == 0) {
@@ -789,7 +804,7 @@ static void *ip_vs_conn_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 	idx = l - ip_vs_conn_tab;
 	ct_read_unlock_bh(idx);
 
-	while (++idx < IP_VS_CONN_TAB_SIZE) {
+	while (++idx < ip_vs_conn_tab_size) {
 		ct_read_lock_bh(idx);
 		list_for_each_entry(cp, &ip_vs_conn_tab[idx], c_list) {
 			seq->private = &ip_vs_conn_tab[idx];
@@ -972,8 +987,8 @@ void ip_vs_random_dropentry(void)
 	/*
 	 * Randomly scan 1/32 of the whole table every second
 	 */
-	for (idx = 0; idx < (IP_VS_CONN_TAB_SIZE>>5); idx++) {
-		unsigned hash = net_random() & IP_VS_CONN_TAB_MASK;
+	for (idx = 0; idx < (ip_vs_conn_tab_size>>5); idx++) {
+		unsigned hash = net_random() & ip_vs_conn_tab_mask;
 
 		/*
 		 *  Lock is actually needed in this loop.
@@ -1025,7 +1040,7 @@ static void ip_vs_conn_flush(void)
 	struct ip_vs_conn *cp;
 
   flush_again:
-	for (idx=0; idx<IP_VS_CONN_TAB_SIZE; idx++) {
+	for (idx=0; idx<ip_vs_conn_tab_size; idx++) {
 		/*
 		 *  Lock is actually needed in this loop.
 		 */
@@ -1056,10 +1071,14 @@ int __init ip_vs_conn_init(void)
 {
 	int idx;
 
+	/* Compute size and mask */
+	ip_vs_conn_tab_size = 1 << ip_vs_conn_tab_bits;
+	ip_vs_conn_tab_mask = ip_vs_conn_tab_size - 1;
+
 	/*
 	 * Allocate the connection hash table and initialize its list heads
 	 */
-	ip_vs_conn_tab = vmalloc(IP_VS_CONN_TAB_SIZE*sizeof(struct list_head));
+	ip_vs_conn_tab = vmalloc(ip_vs_conn_tab_size * sizeof(struct list_head));
 	if (!ip_vs_conn_tab)
 		return -ENOMEM;
 
@@ -1074,12 +1093,12 @@ int __init ip_vs_conn_init(void)
 
 	IP_VS_INFO("Connection hash table configured "
 		   "(size=%d, memory=%ldKbytes)\n",
-		   IP_VS_CONN_TAB_SIZE,
-		   (long)(IP_VS_CONN_TAB_SIZE*sizeof(struct list_head))/1024);
+		   ip_vs_conn_tab_size,
+		   (long)(ip_vs_conn_tab_size*sizeof(struct list_head))/1024);
 	IP_VS_DBG(0, "Each connection entry needs %Zd bytes at least\n",
 		  sizeof(struct ip_vs_conn));
 
-	for (idx = 0; idx < IP_VS_CONN_TAB_SIZE; idx++) {
+	for (idx = 0; idx < ip_vs_conn_tab_size; idx++) {
 		INIT_LIST_HEAD(&ip_vs_conn_tab[idx]);
 	}
 
diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
index 0302cf3..6dcadc2 100644
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -1854,7 +1854,7 @@ static int ip_vs_info_seq_show(struct seq_file *seq, void *v)
 	if (v == SEQ_START_TOKEN) {
 		seq_printf(seq,
 			"IP Virtual Server version %d.%d.%d (size=%d)\n",
-			NVERSION(IP_VS_VERSION_CODE), IP_VS_CONN_TAB_SIZE);
+			NVERSION(IP_VS_VERSION_CODE), ip_vs_conn_tab_size);
 		seq_puts(seq,
 			 "Prot LocalAddress:Port Scheduler Flags\n");
 		seq_puts(seq,
@@ -2385,7 +2385,7 @@ do_ip_vs_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
 		char buf[64];
 
 		sprintf(buf, "IP Virtual Server version %d.%d.%d (size=%d)",
-			NVERSION(IP_VS_VERSION_CODE), IP_VS_CONN_TAB_SIZE);
+			NVERSION(IP_VS_VERSION_CODE), ip_vs_conn_tab_size);
 		if (copy_to_user(user, buf, strlen(buf)+1) != 0) {
 			ret = -EFAULT;
 			goto out;
@@ -2398,7 +2398,7 @@ do_ip_vs_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
 	{
 		struct ip_vs_getinfo info;
 		info.version = IP_VS_VERSION_CODE;
-		info.size = IP_VS_CONN_TAB_SIZE;
+		info.size = ip_vs_conn_tab_size;
 		info.num_services = ip_vs_num_services;
 		if (copy_to_user(user, &info, sizeof(info)) != 0)
 			ret = -EFAULT;
@@ -3238,7 +3238,7 @@ static int ip_vs_genl_get_cmd(struct sk_buff *skb, struct genl_info *info)
 	case IPVS_CMD_GET_INFO:
 		NLA_PUT_U32(msg, IPVS_INFO_ATTR_VERSION, IP_VS_VERSION_CODE);
 		NLA_PUT_U32(msg, IPVS_INFO_ATTR_CONN_TAB_SIZE,
-			    IP_VS_CONN_TAB_SIZE);
+			    ip_vs_conn_tab_size);
 		break;
 	}
 
-- 
1.5.6.5