tipc: initiate media type array at compile time

Communication media types are abstracted through the struct 'tipc_media',
one per media type. These structs are allocated statically inside their
respective media file.

Furthermore, in order to be able to reach all instances from a central
location, we keep a static array with pointers to these structs. This
array is currently initialized at runtime, under protection of
tipc_net_lock. However, since the contents of the array itself never
changes after initialization, we can just as well initialize it at
compile time and make it 'const', at the same time making it obvious
that no lock protection is needed here.

This commit makes the array constant and removes the redundant lock
protection.
Signed-off-by: Ying Xue <ying.xue@windriver.com>
Reviewed-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/tipc/bearer.c

 /*
  * net/tipc/bearer.c: TIPC bearer code
  *
- * Copyright (c) 1996-2006, Ericsson AB
+ * Copyright (c) 1996-2006, 2013, Ericsson AB
  * Copyright (c) 2004-2006, 2010-2011, Wind River Systems
  * All rights reserved.
  *
@@ -41,8 +41,13 @@
 
 #define MAX_ADDR_STR 60
 
-static struct tipc_media *media_list[MAX_MEDIA];
-static u32 media_count;
+static struct tipc_media * const media_list[] = {
+	&eth_media_info,
+#ifdef CONFIG_TIPC_MEDIA_IB
+	&ib_media_info,
+#endif
+	NULL
+};
 
 struct tipc_bearer tipc_bearers[MAX_BEARERS];
 
@@ -55,11 +60,11 @@ struct tipc_media *tipc_media_find(const char *name)
 {
 	u32 i;
 
-	for (i = 0; i < media_count; i++) {
+	for (i = 0; media_list[i] != NULL; i++) {
 		if (!strcmp(media_list[i]->name, name))
-			return media_list[i];
+			break;
 	}
-	return NULL;
+	return media_list[i];
 }
 
 /**
@@ -69,44 +74,11 @@ static struct tipc_media *media_find_id(u8 type)
 {
 	u32 i;
 
-	for (i = 0; i < media_count; i++) {
+	for (i = 0; media_list[i] != NULL; i++) {
 		if (media_list[i]->type_id == type)
-			return media_list[i];
+			break;
 	}
-	return NULL;
-}
-
-/**
- * tipc_register_media - register a media type
- *
- * Bearers for this media type must be activated separately at a later stage.
- */
-int tipc_register_media(struct tipc_media *m_ptr)
-{
-	int res = -EINVAL;
-
-	write_lock_bh(&tipc_net_lock);
-
-	if ((strlen(m_ptr->name) + 1) > TIPC_MAX_MEDIA_NAME)
-		goto exit;
-	if (m_ptr->priority > TIPC_MAX_LINK_PRI)
-		goto exit;
-	if ((m_ptr->tolerance < TIPC_MIN_LINK_TOL) ||
-	    (m_ptr->tolerance > TIPC_MAX_LINK_TOL))
-		goto exit;
-	if (media_count >= MAX_MEDIA)
-		goto exit;
-	if (tipc_media_find(m_ptr->name) || media_find_id(m_ptr->type_id))
-		goto exit;
-
-	media_list[media_count] = m_ptr;
-	media_count++;
-	res = 0;
-exit:
-	write_unlock_bh(&tipc_net_lock);
-	if (res)
-		pr_warn("Media <%s> registration error\n", m_ptr->name);
-	return res;
+	return media_list[i];
 }
 
 /**
@@ -144,13 +116,11 @@ struct sk_buff *tipc_media_get_names(void)
 	if (!buf)
 		return NULL;
 
-	read_lock_bh(&tipc_net_lock);
-	for (i = 0; i < media_count; i++) {
+	for (i = 0; media_list[i] != NULL; i++) {
 		tipc_cfg_append_tlv(buf, TIPC_TLV_MEDIA_NAME,
 				    media_list[i]->name,
 				    strlen(media_list[i]->name) + 1);
 	}
-	read_unlock_bh(&tipc_net_lock);
 	return buf;
 }
 
@@ -247,7 +217,7 @@ struct sk_buff *tipc_bearer_get_names(void)
 		return NULL;
 
 	read_lock_bh(&tipc_net_lock);
-	for (i = 0; i < media_count; i++) {
+	for (i = 0; media_list[i] != NULL; i++) {
 		for (j = 0; j < MAX_BEARERS; j++) {
 			b_ptr = &tipc_bearers[j];
 			if (b_ptr->active && (b_ptr->media == media_list[i])) {
@@ -472,5 +442,4 @@ void tipc_bearer_stop(void)
 		if (tipc_bearers[i].active)
 			bearer_disable(&tipc_bearers[i]);
 	}
-	media_count = 0;
 }

net/tipc/bearer.h

 /*
  * net/tipc/bearer.h: Include file for TIPC bearer code
  *
- * Copyright (c) 1996-2006, Ericsson AB
+ * Copyright (c) 1996-2006, 2013, Ericsson AB
  * Copyright (c) 2005, 2010-2011, Wind River Systems
  * All rights reserved.
  *
@@ -157,7 +157,6 @@ extern struct tipc_bearer tipc_bearers[];
 /*
  * TIPC routines available to supported media types
  */
-int tipc_register_media(struct tipc_media *m_ptr);
 
 void tipc_recv_msg(struct sk_buff *buf, struct tipc_bearer *tb_ptr);
 
@@ -171,10 +170,12 @@ int tipc_disable_bearer(const char *name);
  */
 int  tipc_eth_media_start(void);
 void tipc_eth_media_stop(void);
+extern struct tipc_media eth_media_info;
 
 #ifdef CONFIG_TIPC_MEDIA_IB
 int  tipc_ib_media_start(void);
 void tipc_ib_media_stop(void);
+extern struct tipc_media ib_media_info;
 #else
 static inline int tipc_ib_media_start(void) { return 0; }
 static inline void tipc_ib_media_stop(void) { return; }

net/tipc/eth_media.c

 /*
  * net/tipc/eth_media.c: Ethernet bearer support for TIPC
  *
- * Copyright (c) 2001-2007, Ericsson AB
+ * Copyright (c) 2001-2007, 2013, Ericsson AB
  * Copyright (c) 2005-2008, 2011-2013, Wind River Systems
  * All rights reserved.
  *
@@ -57,7 +57,7 @@ struct eth_media {
 	struct work_struct cleanup;
 };
 
-static struct tipc_media eth_media_info;
+
 static struct eth_media eth_media_array[MAX_ETH_MEDIA];
 static int eth_started;
 
@@ -315,7 +315,7 @@ static int eth_msg2addr(const struct tipc_bearer *tb_ptr,
 /*
  * Ethernet media registration info
  */
-static struct tipc_media eth_media_info = {
+struct tipc_media eth_media_info = {
 	.send_msg	= send_msg,
 	.enable_media	= enable_media,
 	.disable_media	= disable_media,
@@ -342,10 +342,6 @@ int tipc_eth_media_start(void)
 	if (eth_started)
 		return -EINVAL;
 
-	res = tipc_register_media(&eth_media_info);
-	if (res)
-		return res;
-
 	res = register_netdevice_notifier(&notifier);
 	if (!res)
 		eth_started = 1;

net/tipc/ib_media.c

@@ -60,7 +60,6 @@ struct ib_media {
 	struct work_struct cleanup;
 };
 
-static struct tipc_media ib_media_info;
 static struct ib_media ib_media_array[MAX_IB_MEDIA];
 static int ib_started;
 
@@ -311,7 +310,7 @@ static int ib_msg2addr(const struct tipc_bearer *tb_ptr,
 /*
  * InfiniBand media registration info
  */
-static struct tipc_media ib_media_info = {
+struct tipc_media ib_media_info = {
 	.send_msg	= send_msg,
 	.enable_media	= enable_media,
 	.disable_media	= disable_media,
@@ -338,10 +337,6 @@ int tipc_ib_media_start(void)
 	if (ib_started)
 		return -EINVAL;
 
-	res = tipc_register_media(&ib_media_info);
-	if (res)
-		return res;
-
 	res = register_netdevice_notifier(&notifier);
 	if (!res)
 		ib_started = 1;