Merge branch 'tipc'

Jon Maloy says:

====================
tipc: clean up media and bearer layer

This commit series aims at facilitating future changes to the
locking policy around nodes, links and bearers.

Currently, we have a big read/write lock (net_lock) that is used for
serializing all changes to the node, link and bearer lists, as well
as to their mutual pointers and references.

But, in order to allow for concurrent access to the contents of these
structures, net_lock is only used in read mode by the data path code,
and hence a finer granular locking policy must be applied inside the
scope of net_lock: a spinlock (node_lock) for each node structure,
and another one (bearer_lock) for protection of bearer structures.

This locking policy has proved hard to maintain. We have several
times encountered contention problems between node_lock and
bearer_lock, and with the advent of the RCU locking mechanism we
feel it is anyway obsolete and ripe for improvements.

We now plan to replace net_lock with an RCU lock, as well as
getting rid of bearer_lock altogether. This will both reduce data
path overhead and make the code more manageable, while reducing the
risk of future lock contention problems.

Prior to these changes, we need to do some necessary cleanup and
code consolidation. This is what we do with this commit series,
before we finally remove bearer_lock. In a later series we will
replace net_lock with an RCU lock.

v2:
 - Re-inserted a removed kerneldoc entry in commit#5, based on
   feedback from D. Miller.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

net/tipc/bcast.c

@@ -481,9 +481,9 @@ void tipc_bclink_recv_pkt(struct sk_buff *buf)
 			tipc_link_recv_bundle(buf);
 		} else if (msg_user(msg) == MSG_FRAGMENTER) {
 			int ret;
-			ret = tipc_link_recv_fragment(&node->bclink.reasm_head,
-						      &node->bclink.reasm_tail,
-						      &buf);
+			ret = tipc_link_frag_rcv(&node->bclink.reasm_head,
+						 &node->bclink.reasm_tail,
+						 &buf);
 			if (ret == LINK_REASM_ERROR)
 				goto unlock;
 			spin_lock_bh(&bc_lock);
@@ -785,7 +785,6 @@ void tipc_bclink_init(void)
 	bcl->owner = &bclink->node;
 	bcl->max_pkt = MAX_PKT_DEFAULT_MCAST;
 	tipc_link_set_queue_limits(bcl, BCLINK_WIN_DEFAULT);
-	spin_lock_init(&bcbearer->bearer.lock);
 	bcl->b_ptr = &bcbearer->bearer;
 	bcl->state = WORKING_WORKING;
 	strlcpy(bcl->name, tipc_bclink_name, TIPC_MAX_LINK_NAME);

net/tipc/bearer.c

@@ -51,7 +51,7 @@ static struct tipc_media * const media_info_array[] = {
 
 struct tipc_bearer tipc_bearers[MAX_BEARERS];
 
-static void bearer_disable(struct tipc_bearer *b_ptr);
+static void bearer_disable(struct tipc_bearer *b_ptr, bool shutting_down);
 
 /**
  * tipc_media_find - locates specified media object by name
@@ -327,12 +327,10 @@ int tipc_enable_bearer(const char *name, u32 disc_domain, u32 priority)
 	b_ptr->net_plane = bearer_id + 'A';
 	b_ptr->active = 1;
 	b_ptr->priority = priority;
-	INIT_LIST_HEAD(&b_ptr->links);
-	spin_lock_init(&b_ptr->lock);
 
 	res = tipc_disc_create(b_ptr, &b_ptr->bcast_addr, disc_domain);
 	if (res) {
-		bearer_disable(b_ptr);
+		bearer_disable(b_ptr, false);
 		pr_warn("Bearer <%s> rejected, discovery object creation failed\n",
 			name);
 		goto exit;
@@ -350,20 +348,9 @@ int tipc_enable_bearer(const char *name, u32 disc_domain, u32 priority)
  */
 static int tipc_reset_bearer(struct tipc_bearer *b_ptr)
 {
-	struct tipc_link *l_ptr;
-	struct tipc_link *temp_l_ptr;
-
 	read_lock_bh(&tipc_net_lock);
 	pr_info("Resetting bearer <%s>\n", b_ptr->name);
-	spin_lock_bh(&b_ptr->lock);
-	list_for_each_entry_safe(l_ptr, temp_l_ptr, &b_ptr->links, link_list) {
-		struct tipc_node *n_ptr = l_ptr->owner;
-
-		spin_lock_bh(&n_ptr->lock);
-		tipc_link_reset(l_ptr);
-		spin_unlock_bh(&n_ptr->lock);
-	}
-	spin_unlock_bh(&b_ptr->lock);
+	tipc_link_reset_list(b_ptr->identity);
 	read_unlock_bh(&tipc_net_lock);
 	return 0;
 }
@@ -373,25 +360,14 @@ static int tipc_reset_bearer(struct tipc_bearer *b_ptr)
  *
  * Note: This routine assumes caller holds tipc_net_lock.
  */
-static void bearer_disable(struct tipc_bearer *b_ptr)
+static void bearer_disable(struct tipc_bearer *b_ptr, bool shutting_down)
 {
-	struct tipc_link *l_ptr;
-	struct tipc_link *temp_l_ptr;
-	struct tipc_link_req *temp_req;
-
 	pr_info("Disabling bearer <%s>\n", b_ptr->name);
-	spin_lock_bh(&b_ptr->lock);
 	b_ptr->media->disable_media(b_ptr);
-	list_for_each_entry_safe(l_ptr, temp_l_ptr, &b_ptr->links, link_list) {
-		tipc_link_delete(l_ptr);
-	}
-	temp_req = b_ptr->link_req;
-	b_ptr->link_req = NULL;
-	spin_unlock_bh(&b_ptr->lock);
-
-	if (temp_req)
-		tipc_disc_delete(temp_req);
 
+	tipc_link_delete_list(b_ptr->identity, shutting_down);
+	if (b_ptr->link_req)
+		tipc_disc_delete(b_ptr->link_req);
 	memset(b_ptr, 0, sizeof(struct tipc_bearer));
 }
 
@@ -406,7 +382,7 @@ int tipc_disable_bearer(const char *name)
 		pr_warn("Attempt to disable unknown bearer <%s>\n", name);
 		res = -EINVAL;
 	} else {
-		bearer_disable(b_ptr);
+		bearer_disable(b_ptr, false);
 		res = 0;
 	}
 	write_unlock_bh(&tipc_net_lock);
@@ -626,6 +602,6 @@ void tipc_bearer_stop(void)
 
 	for (i = 0; i < MAX_BEARERS; i++) {
 		if (tipc_bearers[i].active)
-			bearer_disable(&tipc_bearers[i]);
+			bearer_disable(&tipc_bearers[i], true);
 	}
 }

net/tipc/bearer.h

@@ -107,10 +107,8 @@ struct tipc_media {
 
 /**
  * struct tipc_bearer - Generic TIPC bearer structure
- * @dev: ptr to associated network device
- * @usr_handle: pointer to additional media-specific information about bearer
+ * @media_ptr: pointer to additional media-specific information about bearer
  * @mtu: max packet size bearer can support
- * @lock: spinlock for controlling access to bearer
  * @addr: media-specific address associated with bearer
  * @name: bearer name (format = media:interface)
  * @media: ptr to media structure associated with bearer
@@ -120,7 +118,6 @@ struct tipc_media {
  * @tolerance: default link tolerance for bearer
  * @identity: array index of this bearer within TIPC bearer array
  * @link_req: ptr to (optional) structure making periodic link setup requests
- * @links: list of non-congested links associated with bearer
  * @active: non-zero if bearer structure is represents a bearer
  * @net_plane: network plane ('A' through 'H') currently associated with bearer
  * @nodes: indicates which nodes in cluster can be reached through bearer
@@ -134,15 +131,13 @@ struct tipc_bearer {
 	u32 mtu;				/* initalized by media */
 	struct tipc_media_addr addr;		/* initalized by media */
 	char name[TIPC_MAX_BEARER_NAME];
-	spinlock_t lock;
 	struct tipc_media *media;
 	struct tipc_media_addr bcast_addr;
 	u32 priority;
 	u32 window;
 	u32 tolerance;
 	u32 identity;
 	struct tipc_link_req *link_req;
-	struct list_head links;
 	int active;
 	char net_plane;
 	struct tipc_node_map nodes;

net/tipc/core.c

@@ -1,7 +1,7 @@
 /*
  * net/tipc/core.c: TIPC module code
  *
- * Copyright (c) 2003-2006, Ericsson AB
+ * Copyright (c) 2003-2006, 2013, Ericsson AB
  * Copyright (c) 2005-2006, 2010-2013, Wind River Systems
  * All rights reserved.
  *