[PATCH] expectation use a slab instead of kmalloc

[Pablo Neira <pablo@eurodev.net>]

[-- Attachment #1: Type: text/plain, Size: 622 bytes --]

Hi,

Attached a patch to use a slab for expectations, I think that this could 
increase a bit the performance in a system which has lots of expectations.

I also moved the increment of an expectation refcount to 
ip_conntrack_expect_alloc because we could use ip_conntrack_expect_put 
to release an expectation which we just allocated in a helper (well, in 
current helpers I didn't find any case but there are weird protocols 
outthere so I think that it's not a bad idea).

Patrick, if you consider that it's ok, would you be willing to add this 
to pom-ng? If I'm missing something, please let me know.

regards,
Pablo

[-- Attachment #2: slab-expectation.patch --]
[-- Type: text/x-patch, Size: 3611 bytes --]

diff -u -r1.1.1.1 ip_conntrack_core.c
--- a/net/ipv4/netfilter/ip_conntrack_core.c	11 May 2004 13:07:08 -0000	1.1.1.1
+++ b/net/ipv4/netfilter/ip_conntrack_core.c	30 May 2004 13:08:00 -0000
@@ -67,6 +67,7 @@
 static atomic_t ip_conntrack_count = ATOMIC_INIT(0);
 struct list_head *ip_conntrack_hash;
 static kmem_cache_t *ip_conntrack_cachep;
+static kmem_cache_t *ip_conntrack_expect_cachep;
 struct ip_conntrack ip_conntrack_untracked;
 
 extern struct ip_conntrack_protocol ip_conntrack_generic_protocol;
@@ -176,7 +177,7 @@
 	IP_NF_ASSERT(atomic_read(&exp->use));
 	IP_NF_ASSERT(!timer_pending(&exp->timeout));
 
-	kfree(exp);
+	kmem_cache_free(ip_conntrack_expect_cachep, exp);
 }
 
 
@@ -335,7 +336,7 @@
 			list_del(&ct->master->expected_list);
 			master = ct->master->expectant;
 		}
-		kfree(ct->master);
+		kmem_cache_free(ip_conntrack_expect_cachep, ct->master);
 	}
 	WRITE_UNLOCK(&ip_conntrack_lock);
 
@@ -923,16 +924,17 @@
 ip_conntrack_expect_alloc()
 {
 	struct ip_conntrack_expect *new;
-	
-	new = (struct ip_conntrack_expect *)
-		kmalloc(sizeof(struct ip_conntrack_expect), GFP_ATOMIC);
+
+	new = kmem_cache_alloc(ip_conntrack_expect_cachep, GFP_ATOMIC);
 	if (!new) {
 		DEBUGP("expect_related: OOM allocating expect\n");
 		return NULL;
 	}
 
+	DEBUGP("new expectation %p allocated\n", new);
 	/* tuple_cmp compares whole union, we have to initialized cleanly */
 	memset(new, 0, sizeof(struct ip_conntrack_expect));
+	atomic_set(&new->use, 1);
 
 	return new;
 }
@@ -944,7 +946,6 @@
 	DEBUGP("new expectation %p of conntrack %p\n", new, related_to);
 	new->expectant = related_to;
 	new->sibling = NULL;
-	atomic_set(&new->use, 1);
 
 	/* add to expected list for this connection */
 	list_add(&new->expected_list, &related_to->sibling_list);
@@ -998,7 +999,8 @@
 		}
 
 		WRITE_UNLOCK(&ip_conntrack_lock);
-		kfree(expect);
+		/* This expectation is not inserted so no need to lock */
+		kmem_cache_free(ip_conntrack_expect_cachep, expect);
 		return -EEXIST;
 
 	} else if (related_to->helper->max_expected && 
@@ -1017,7 +1019,7 @@
 				       related_to->helper->name,
  		    	       	       NIPQUAD(related_to->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip),
  		    	       	       NIPQUAD(related_to->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.ip));
-			kfree(expect);
+			kmem_cache_free(ip_conntrack_expect_cachep, expect);
 			return -EPERM;
 		}
 		DEBUGP("ip_conntrack: max number of expected "
@@ -1058,7 +1060,7 @@
 		WRITE_UNLOCK(&ip_conntrack_lock);
 		DEBUGP("expect_related: busy!\n");
 
-		kfree(expect);
+		kmem_cache_free(ip_conntrack_expect_cachep, expect);
 		return -EBUSY;
 	}
 
@@ -1379,6 +1381,7 @@
 	}
 
 	kmem_cache_destroy(ip_conntrack_cachep);
+	kmem_cache_destroy(ip_conntrack_expect_cachep);
 	vfree(ip_conntrack_hash);
 	nf_unregister_sockopt(&so_getorigdst);
 }
@@ -1431,6 +1434,15 @@
 		printk(KERN_ERR "Unable to create ip_conntrack slab cache\n");
 		goto err_free_hash;
 	}
+
+        ip_conntrack_expect_cachep = kmem_cache_create("ip_conntrack_expect",
+                                          sizeof(struct ip_conntrack_expect),
+					   0, SLAB_HWCACHE_ALIGN, NULL, NULL);
+        if (!ip_conntrack_expect_cachep) {
+                printk(KERN_ERR "Unable to create ip_expect slab cache\n");
+                goto err_free_conntrack_slab;
+        }
+
 	/* Don't NEED lock here, but good form anyway. */
 	WRITE_LOCK(&ip_conntrack_lock);
 	/* Sew in builtin protocols. */
@@ -1458,6 +1470,8 @@
 
 	return ret;
 
+err_free_conntrack_slab:
+	kmem_cache_destroy(ip_conntrack_cachep);
 err_free_hash:
 	vfree(ip_conntrack_hash);
 err_unreg_sockopt: