[PATCH] Consolidate creation of kmem caches with "calculated" names

[Pavel Emelyanov <xemul@openvz.org>]

Some places in network (like protocol registration and dccp)
generate the kmem cache name with snprintf() to create caches
for several protocols with similar names.

Make the routine that makes this in one place. Possibly, this
is better to be put in mm/sl[uoa]b.c, but I haven't found
any other places in kernel that require such functionality,
so put this code (temporary?) in net/core/util.c

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>

---

diff --git a/include/net/sock.h b/include/net/sock.h
index 453c79d..8040d59 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -601,6 +601,10 @@ struct proto {
 extern int proto_register(struct proto *prot, int alloc_slab);
 extern void proto_unregister(struct proto *prot);
 
+struct kmem_cache *kmem_cache_create_va(int size, unsigned long flags,
+		char *fmt, ...) __attribute__ ((format (printf, 3, 4)));
+void kmem_cache_destroy_va(struct kmem_cache *);
+
 #ifdef SOCK_REFCNT_DEBUG
 static inline void sk_refcnt_debug_inc(struct sock *sk)
 {
diff --git a/net/core/sock.c b/net/core/sock.c
index d45ecdc..65f485a 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1777,10 +1777,6 @@ static LIST_HEAD(proto_list);
 
 int proto_register(struct proto *prot, int alloc_slab)
 {
-	char *request_sock_slab_name = NULL;
-	char *timewait_sock_slab_name;
-	int rc = -ENOBUFS;
-
 	if (alloc_slab) {
 		prot->slab = kmem_cache_create(prot->name, prot->obj_size, 0,
 					       SLAB_HWCACHE_ALIGN, NULL);
@@ -1792,62 +1788,44 @@ int proto_register(struct proto *prot, int alloc_slab)
 		}
 
 		if (prot->rsk_prot != NULL) {
-			static const char mask[] = "request_sock_%s";
-
-			request_sock_slab_name = kmalloc(strlen(prot->name) + sizeof(mask) - 1, GFP_KERNEL);
-			if (request_sock_slab_name == NULL)
-				goto out_free_sock_slab;
-
-			sprintf(request_sock_slab_name, mask, prot->name);
-			prot->rsk_prot->slab = kmem_cache_create(request_sock_slab_name,
-								 prot->rsk_prot->obj_size, 0,
-								 SLAB_HWCACHE_ALIGN, NULL);
+			prot->rsk_prot->slab = kmem_cache_create_va(
+					prot->rsk_prot->obj_size,
+					SLAB_HWCACHE_ALIGN,
+					"request_sock_%s", prot->name);
 
 			if (prot->rsk_prot->slab == NULL) {
 				printk(KERN_CRIT "%s: Can't create request sock SLAB cache!\n",
 				       prot->name);
-				goto out_free_request_sock_slab_name;
+				goto out_rsk;
 			}
 		}
 
 		if (prot->twsk_prot != NULL) {
-			static const char mask[] = "tw_sock_%s";
+			prot->twsk_prot->twsk_slab = kmem_cache_create_va(
+					prot->twsk_prot->twsk_obj_size,
+					SLAB_HWCACHE_ALIGN,
+					"tw_sock_%s", prot->name);
 
-			timewait_sock_slab_name = kmalloc(strlen(prot->name) + sizeof(mask) - 1, GFP_KERNEL);
-
-			if (timewait_sock_slab_name == NULL)
-				goto out_free_request_sock_slab;
-
-			sprintf(timewait_sock_slab_name, mask, prot->name);
-			prot->twsk_prot->twsk_slab =
-				kmem_cache_create(timewait_sock_slab_name,
-						  prot->twsk_prot->twsk_obj_size,
-						  0, SLAB_HWCACHE_ALIGN,
-						  NULL);
 			if (prot->twsk_prot->twsk_slab == NULL)
-				goto out_free_timewait_sock_slab_name;
+				goto out_twsk;
 		}
 	}
 
 	write_lock(&proto_list_lock);
 	list_add(&prot->node, &proto_list);
 	write_unlock(&proto_list_lock);
-	rc = 0;
-out:
-	return rc;
-out_free_timewait_sock_slab_name:
-	kfree(timewait_sock_slab_name);
-out_free_request_sock_slab:
+	return 0;
+
+out_twsk:
 	if (prot->rsk_prot && prot->rsk_prot->slab) {
-		kmem_cache_destroy(prot->rsk_prot->slab);
+		kmem_cache_destroy_va(prot->rsk_prot->slab);
 		prot->rsk_prot->slab = NULL;
 	}
-out_free_request_sock_slab_name:
-	kfree(request_sock_slab_name);
-out_free_sock_slab:
+out_rsk:
 	kmem_cache_destroy(prot->slab);
 	prot->slab = NULL;
-	goto out;
+out:
+	return -ENOBUFS;
 }
 
 EXPORT_SYMBOL(proto_register);
diff --git a/net/core/utils.c b/net/core/utils.c
index 0bf17da..eccc71b 100644
--- a/net/core/utils.c
+++ b/net/core/utils.c
@@ -293,3 +293,41 @@ out:
 }
 
 EXPORT_SYMBOL(in6_pton);
+
+struct kmem_cache *kmem_cache_create_va(int size, unsigned long flags,
+		char *fmt, ...)
+{
+	char *name, str[64];
+	struct kmem_cache *c;
+	va_list args;
+
+	va_start(args, fmt);
+	vsnprintf(str, sizeof(str), fmt, args);
+	va_end(args);
+
+	name = kstrdup(str, GFP_KERNEL);
+	if (name == NULL)
+		goto err_name;
+
+	c = kmem_cache_create(name, size, 0, flags, NULL);
+	if (c == NULL)
+		goto err_cache;
+
+	return c;
+
+err_cache:
+	kfree(name);
+err_name:
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(kmem_cache_create_va);
+
+void kmem_cache_destroy_va(struct kmem_cache *c)
+{
+	const char *name;
+
+	name = kmem_cache_name(c);
+	kmem_cache_destroy(c);
+	kfree(name);
+}
+EXPORT_SYMBOL_GPL(kmem_cache_destroy_va);
diff --git a/net/dccp/ccid.c b/net/dccp/ccid.c
index c45088b..9d2cc27 100644
--- a/net/dccp/ccid.c
+++ b/net/dccp/ccid.c
@@ -56,51 +56,21 @@ static inline void ccids_read_unlock(void)
 #define ccids_read_unlock() do { } while(0)
 #endif
 
-static struct kmem_cache *ccid_kmem_cache_create(int obj_size, const char *fmt,...)
-{
-	struct kmem_cache *slab;
-	char slab_name_fmt[32], *slab_name;
-	va_list args;
-
-	va_start(args, fmt);
-	vsnprintf(slab_name_fmt, sizeof(slab_name_fmt), fmt, args);
-	va_end(args);
-
-	slab_name = kstrdup(slab_name_fmt, GFP_KERNEL);
-	if (slab_name == NULL)
-		return NULL;
-	slab = kmem_cache_create(slab_name, sizeof(struct ccid) + obj_size, 0,
-				 SLAB_HWCACHE_ALIGN, NULL);
-	if (slab == NULL)
-		kfree(slab_name);
-	return slab;
-}
-
-static void ccid_kmem_cache_destroy(struct kmem_cache *slab)
-{
-	if (slab != NULL) {
-		const char *name = kmem_cache_name(slab);
-
-		kmem_cache_destroy(slab);
-		kfree(name);
-	}
-}
-
 int ccid_register(struct ccid_operations *ccid_ops)
 {
 	int err = -ENOBUFS;
 
 	ccid_ops->ccid_hc_rx_slab =
-			ccid_kmem_cache_create(ccid_ops->ccid_hc_rx_obj_size,
-					       "%s_hc_rx_sock",
-					       ccid_ops->ccid_name);
+			kmem_cache_create_va(ccid_ops->ccid_hc_rx_obj_size,
+					SLAB_HWCACHE_ALIGN,
+					"%s_hc_rx_sock", ccid_ops->ccid_name);
 	if (ccid_ops->ccid_hc_rx_slab == NULL)
 		goto out;
 
 	ccid_ops->ccid_hc_tx_slab =
-			ccid_kmem_cache_create(ccid_ops->ccid_hc_tx_obj_size,
-					       "%s_hc_tx_sock",
-					       ccid_ops->ccid_name);
+			kmem_cache_create_va(ccid_ops->ccid_hc_tx_obj_size,
+					SLAB_HWCACHE_ALIGN,
+					"%s_hc_tx_sock", ccid_ops->ccid_name);
 	if (ccid_ops->ccid_hc_tx_slab == NULL)
 		goto out_free_rx_slab;
 
@@ -118,12 +88,13 @@ int ccid_register(struct ccid_operations *ccid_ops)
 		ccid_ops->ccid_id, ccid_ops->ccid_name);
 out:
 	return err;
+
 out_free_tx_slab:
-	ccid_kmem_cache_destroy(ccid_ops->ccid_hc_tx_slab);
+	kmem_cache_destroy_va(ccid_ops->ccid_hc_tx_slab);
 	ccid_ops->ccid_hc_tx_slab = NULL;
 	goto out;
 out_free_rx_slab:
-	ccid_kmem_cache_destroy(ccid_ops->ccid_hc_rx_slab);
+	kmem_cache_destroy_va(ccid_ops->ccid_hc_rx_slab);
 	ccid_ops->ccid_hc_rx_slab = NULL;
 	goto out;
 }
@@ -136,9 +107,9 @@ int ccid_unregister(struct ccid_operations *ccid_ops)
 	ccids[ccid_ops->ccid_id] = NULL;
 	ccids_write_unlock();
 
-	ccid_kmem_cache_destroy(ccid_ops->ccid_hc_tx_slab);
+	kmem_cache_destroy_va(ccid_ops->ccid_hc_tx_slab);
 	ccid_ops->ccid_hc_tx_slab = NULL;
-	ccid_kmem_cache_destroy(ccid_ops->ccid_hc_rx_slab);
+	kmem_cache_destroy_va(ccid_ops->ccid_hc_rx_slab);
 	ccid_ops->ccid_hc_rx_slab = NULL;
 
 	pr_info("CCID: Unregistered CCID %d (%s)\n",