[NETFILTER] ip_conntrack: Make "hashsize" conntrack parameter writable
authorHarald Welte <laforge@netfilter.org>
Sun, 16 Oct 2005 12:22:59 +0000 (14:22 +0200)
committerArnaldo Carvalho de Melo <acme@mandriva.com>
Wed, 26 Oct 2005 02:19:27 +0000 (00:19 -0200)
It's fairly simple to resize the hash table, but currently you need to
remove and reinsert the module.  That's bad (we lose connection
state).  Harald has even offered to write a daemon which sets this
based on load.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
net/ipv4/netfilter/ip_conntrack_core.c

index 07a80b5..422ab68 100644 (file)
@@ -50,7 +50,7 @@
 #include <linux/netfilter_ipv4/ip_conntrack_core.h>
 #include <linux/netfilter_ipv4/listhelp.h>
 
-#define IP_CONNTRACK_VERSION   "2.3"
+#define IP_CONNTRACK_VERSION   "2.4"
 
 #if 0
 #define DEBUGP printk
@@ -148,16 +148,20 @@ DEFINE_PER_CPU(struct ip_conntrack_stat, ip_conntrack_stat);
 static int ip_conntrack_hash_rnd_initted;
 static unsigned int ip_conntrack_hash_rnd;
 
-static u_int32_t
-hash_conntrack(const struct ip_conntrack_tuple *tuple)
+static u_int32_t __hash_conntrack(const struct ip_conntrack_tuple *tuple,
+                           unsigned int size, unsigned int rnd)
 {
-#if 0
-       dump_tuple(tuple);
-#endif
        return (jhash_3words(tuple->src.ip,
                             (tuple->dst.ip ^ tuple->dst.protonum),
                             (tuple->src.u.all | (tuple->dst.u.all << 16)),
-                            ip_conntrack_hash_rnd) % ip_conntrack_htable_size);
+                            rnd) % size);
+}
+
+static u_int32_t
+hash_conntrack(const struct ip_conntrack_tuple *tuple)
+{
+       return __hash_conntrack(tuple, ip_conntrack_htable_size,
+                               ip_conntrack_hash_rnd);
 }
 
 int
@@ -1341,14 +1345,13 @@ static int kill_all(struct ip_conntrack *i, void *data)
        return 1;
 }
 
-static void free_conntrack_hash(void)
+static void free_conntrack_hash(struct list_head *hash, int vmalloced,int size)
 {
-       if (ip_conntrack_vmalloc)
-               vfree(ip_conntrack_hash);
+       if (vmalloced)
+               vfree(hash);
        else
-               free_pages((unsigned long)ip_conntrack_hash, 
-                          get_order(sizeof(struct list_head)
-                                    * ip_conntrack_htable_size));
+               free_pages((unsigned long)hash, 
+                          get_order(sizeof(struct list_head) * size));
 }
 
 void ip_conntrack_flush()
@@ -1378,12 +1381,83 @@ void ip_conntrack_cleanup(void)
        ip_conntrack_flush();
        kmem_cache_destroy(ip_conntrack_cachep);
        kmem_cache_destroy(ip_conntrack_expect_cachep);
-       free_conntrack_hash();
+       free_conntrack_hash(ip_conntrack_hash, ip_conntrack_vmalloc,
+                           ip_conntrack_htable_size);
        nf_unregister_sockopt(&so_getorigdst);
 }
 
-static int hashsize;
-module_param(hashsize, int, 0400);
+static struct list_head *alloc_hashtable(int size, int *vmalloced)
+{
+       struct list_head *hash;
+       unsigned int i;
+
+       *vmalloced = 0; 
+       hash = (void*)__get_free_pages(GFP_KERNEL, 
+                                      get_order(sizeof(struct list_head)
+                                                * size));
+       if (!hash) { 
+               *vmalloced = 1;
+               printk(KERN_WARNING"ip_conntrack: falling back to vmalloc.\n");
+               hash = vmalloc(sizeof(struct list_head) * size);
+       }
+
+       if (hash)
+               for (i = 0; i < size; i++)
+                       INIT_LIST_HEAD(&hash[i]);
+
+       return hash;
+}
+
+int set_hashsize(const char *val, struct kernel_param *kp)
+{
+       int i, bucket, hashsize, vmalloced;
+       int old_vmalloced, old_size;
+       int rnd;
+       struct list_head *hash, *old_hash;
+       struct ip_conntrack_tuple_hash *h;
+
+       /* On boot, we can set this without any fancy locking. */
+       if (!ip_conntrack_htable_size)
+               return param_set_int(val, kp);
+
+       hashsize = simple_strtol(val, NULL, 0);
+       if (!hashsize)
+               return -EINVAL;
+
+       hash = alloc_hashtable(hashsize, &vmalloced);
+       if (!hash)
+               return -ENOMEM;
+
+       /* We have to rehash for the new table anyway, so we also can 
+        * use a new random seed */
+       get_random_bytes(&rnd, 4);
+
+       write_lock_bh(&ip_conntrack_lock);
+       for (i = 0; i < ip_conntrack_htable_size; i++) {
+               while (!list_empty(&ip_conntrack_hash[i])) {
+                       h = list_entry(ip_conntrack_hash[i].next,
+                                      struct ip_conntrack_tuple_hash, list);
+                       list_del(&h->list);
+                       bucket = __hash_conntrack(&h->tuple, hashsize, rnd);
+                       list_add_tail(&h->list, &hash[bucket]);
+               }
+       }
+       old_size = ip_conntrack_htable_size;
+       old_vmalloced = ip_conntrack_vmalloc;
+       old_hash = ip_conntrack_hash;
+
+       ip_conntrack_htable_size = hashsize;
+       ip_conntrack_vmalloc = vmalloced;
+       ip_conntrack_hash = hash;
+       ip_conntrack_hash_rnd = rnd;
+       write_unlock_bh(&ip_conntrack_lock);
+
+       free_conntrack_hash(old_hash, old_vmalloced, old_size);
+       return 0;
+}
+
+module_param_call(hashsize, set_hashsize, param_get_uint,
+                 &ip_conntrack_htable_size, 0600);
 
 int __init ip_conntrack_init(void)
 {
@@ -1392,9 +1466,7 @@ int __init ip_conntrack_init(void)
 
        /* Idea from tcp.c: use 1/16384 of memory.  On i386: 32MB
         * machine has 256 buckets.  >= 1GB machines have 8192 buckets. */
-       if (hashsize) {
-               ip_conntrack_htable_size = hashsize;
-       } else {
+       if (!ip_conntrack_htable_size) {
                ip_conntrack_htable_size
                        = (((num_physpages << PAGE_SHIFT) / 16384)
                           / sizeof(struct list_head));
@@ -1416,20 +1488,8 @@ int __init ip_conntrack_init(void)
                return ret;
        }
 
-       /* AK: the hash table is twice as big than needed because it
-          uses list_head.  it would be much nicer to caches to use a
-          single pointer list head here. */
-       ip_conntrack_vmalloc = 0; 
-       ip_conntrack_hash 
-               =(void*)__get_free_pages(GFP_KERNEL, 
-                                        get_order(sizeof(struct list_head)
-                                                  *ip_conntrack_htable_size));
-       if (!ip_conntrack_hash) { 
-               ip_conntrack_vmalloc = 1;
-               printk(KERN_WARNING "ip_conntrack: falling back to vmalloc.\n");
-               ip_conntrack_hash = vmalloc(sizeof(struct list_head)
-                                           * ip_conntrack_htable_size);
-       }
+       ip_conntrack_hash = alloc_hashtable(ip_conntrack_htable_size,
+                                           &ip_conntrack_vmalloc);
        if (!ip_conntrack_hash) {
                printk(KERN_ERR "Unable to create ip_conntrack_hash\n");
                goto err_unreg_sockopt;
@@ -1461,9 +1521,6 @@ int __init ip_conntrack_init(void)
        ip_ct_protos[IPPROTO_ICMP] = &ip_conntrack_protocol_icmp;
        write_unlock_bh(&ip_conntrack_lock);
 
-       for (i = 0; i < ip_conntrack_htable_size; i++)
-               INIT_LIST_HEAD(&ip_conntrack_hash[i]);
-
        /* For use by ipt_REJECT */
        ip_ct_attach = ip_conntrack_attach;
 
@@ -1478,7 +1535,8 @@ int __init ip_conntrack_init(void)
 err_free_conntrack_slab:
        kmem_cache_destroy(ip_conntrack_cachep);
 err_free_hash:
-       free_conntrack_hash();
+       free_conntrack_hash(ip_conntrack_hash, ip_conntrack_vmalloc,
+                           ip_conntrack_htable_size);
 err_unreg_sockopt:
        nf_unregister_sockopt(&so_getorigdst);