[TIPC]: Fixed link switchover bugs

Incorporates several related fixes:
- switchover now occurs when switching from an active link to a standby link
- failure of a standby link no longer initiates switchover
- links now display correct # of received packtes following reactivation

Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
Signed-off-by: Per Liden <per.liden@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 31 insertions, 8 deletions

diff --git a/net/tipc/link.c b/net/tipc/link.c
index d7668b8abb2d..d64658053746 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -690,6 +690,7 @@ void tipc_link_reset(struct link *l_ptr)
         struct sk_buff *buf;
         u32 prev_state = l_ptr->state;
         u32 checkpoint = l_ptr->next_in_no;
+        int was_active_link = tipc_link_is_active(l_ptr);
         
         msg_set_session(l_ptr->pmsg, msg_session(l_ptr->pmsg) + 1);
 
@@ -711,7 +712,7 @@ void tipc_link_reset(struct link *l_ptr)
         tipc_printf(TIPC_CONS, "\nReset link <%s>\n", l_ptr->name);
         dbg_link_dump();
 #endif
-        if (tipc_node_has_active_links(l_ptr->owner) &&
+        if (was_active_link && tipc_node_has_active_links(l_ptr->owner) &&
             l_ptr->owner->permit_changeover) {
                 l_ptr->reset_checkpoint = checkpoint;
                 l_ptr->exp_msg_count = START_CHANGEOVER;
@@ -754,7 +755,7 @@ void tipc_link_reset(struct link *l_ptr)
 
 static void link_activate(struct link *l_ptr)
 {
-        l_ptr->next_in_no = 1;
+        l_ptr->next_in_no = l_ptr->stats.recv_info = 1;
         tipc_node_link_up(l_ptr->owner, l_ptr);
         tipc_bearer_add_dest(l_ptr->b_ptr, l_ptr->addr);
         link_send_event(tipc_cfg_link_event, l_ptr, 1);
@@ -2303,12 +2304,18 @@ void tipc_link_tunnel(struct link *l_ptr,
         u32 length = msg_size(msg);
 
         tunnel = l_ptr->owner->active_links[selector & 1];
-        if (!tipc_link_is_up(tunnel))
+        if (!tipc_link_is_up(tunnel)) {
+                warn("Link changeover error, "
+                     "tunnel link no longer available\n");
                 return;
+        }
         msg_set_size(tunnel_hdr, length + INT_H_SIZE);
         buf = buf_acquire(length + INT_H_SIZE);
-        if (!buf)
+        if (!buf) {
+                warn("Link changeover error, "
+                     "unable to send tunnel msg\n");
                 return;
+        }
         memcpy(buf->data, (unchar *)tunnel_hdr, INT_H_SIZE);
         memcpy(buf->data + INT_H_SIZE, (unchar *)msg, length);
         dbg("%c->%c:", l_ptr->b_ptr->net_plane, tunnel->b_ptr->net_plane);
@@ -2328,19 +2335,23 @@ void tipc_link_changeover(struct link *l_ptr)
         u32 msgcount = l_ptr->out_queue_size;
         struct sk_buff *crs = l_ptr->first_out;
         struct link *tunnel = l_ptr->owner->active_links[0];
-        int split_bundles = tipc_node_has_redundant_links(l_ptr->owner);
         struct tipc_msg tunnel_hdr;
+        int split_bundles;
 
         if (!tunnel)
                 return;
 
-        if (!l_ptr->owner->permit_changeover)
+        if (!l_ptr->owner->permit_changeover) {
+                warn("Link changeover error, "
+                     "peer did not permit changeover\n");
                 return;
+        }
 
         msg_init(&tunnel_hdr, CHANGEOVER_PROTOCOL,
                  ORIGINAL_MSG, TIPC_OK, INT_H_SIZE, l_ptr->addr);
         msg_set_bearer_id(&tunnel_hdr, l_ptr->peer_bearer_id);
         msg_set_msgcnt(&tunnel_hdr, msgcount);
+        dbg("Link changeover requires %u tunnel messages\n", msgcount);
 
         if (!l_ptr->first_out) {
                 struct sk_buff *buf;
@@ -2360,6 +2371,9 @@ void tipc_link_changeover(struct link *l_ptr)
                 return;
         }
 
+        split_bundles = (l_ptr->owner->active_links[0] != 
+                         l_ptr->owner->active_links[1]);
+
         while (crs) {
                 struct tipc_msg *msg = buf_msg(crs);
 
@@ -2497,11 +2511,13 @@ static int link_recv_changeover_msg(struct link **l_ptr,
                      dest_link->name);
                 tipc_link_reset(dest_link);
                 dest_link->exp_msg_count = msg_count;
+                dbg("Expecting %u tunnelled messages\n", msg_count);
                 if (!msg_count)
                         goto exit;
         } else if (dest_link->exp_msg_count == START_CHANGEOVER) {
                 msg_dbg(tunnel_msg, "BLK/FIRST/<REC<");
                 dest_link->exp_msg_count = msg_count;
+                dbg("Expecting %u tunnelled messages\n", msg_count);
                 if (!msg_count)
                         goto exit;
         }
@@ -2509,6 +2525,8 @@ static int link_recv_changeover_msg(struct link **l_ptr,
         /* Receive original message */
 
         if (dest_link->exp_msg_count == 0) {
+                warn("Link switchover error, "
+                     "got too many tunnelled messages\n");
                 msg_dbg(tunnel_msg, "OVERDUE/DROP/<REC<");
                 dbg_print_link(dest_link, "LINK:");
                 goto exit;
diff --git a/net/tipc/node.c b/net/tipc/node.c
index 5f097547d3e3..ce9678efa98a 100644
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -125,6 +125,8 @@ void tipc_node_link_up(struct node *n_ptr, struct link *l_ptr)
 {
         struct link **active = &n_ptr->active_links[0];
 
+        n_ptr->working_links++;
+
         info("Established link <%s> on network plane %c\n",
              l_ptr->name, l_ptr->b_ptr->net_plane);
         
@@ -185,6 +187,8 @@ void tipc_node_link_down(struct node *n_ptr, struct link *l_ptr)
 {
         struct link **active;
 
+        n_ptr->working_links--;
+
         if (!tipc_link_is_active(l_ptr)) {
                 info("Lost standby link <%s> on network plane %c\n",
                      l_ptr->name, l_ptr->b_ptr->net_plane);
@@ -214,8 +218,7 @@ int tipc_node_has_active_links(struct node *n_ptr)
 
 int tipc_node_has_redundant_links(struct node *n_ptr)
 {
-        return (tipc_node_has_active_links(n_ptr) &&
-                (n_ptr->active_links[0] != n_ptr->active_links[1]));
+        return (n_ptr->working_links > 1);
 }
 
 static int tipc_node_has_active_routes(struct node *n_ptr)
diff --git a/net/tipc/node.h b/net/tipc/node.h
index 781126e084ae..a07cc79ea637 100644
--- a/net/tipc/node.h
+++ b/net/tipc/node.h
@@ -51,6 +51,7 @@
  * @nsub: list of "node down" subscriptions monitoring node
  * @active_links: pointers to active links to node
  * @links: pointers to all links to node
+ * @working_links: number of working links to node (both active and standby)
  * @link_cnt: number of links to node
  * @permit_changeover: non-zero if node has redundant links to this system
  * @routers: bitmap (used for multicluster communication)
@@ -76,6 +77,7 @@ struct node {
         struct link *active_links[2];
         struct link *links[MAX_BEARERS];
         int link_cnt;
+        int working_links;
         int permit_changeover;
         u32 routers[512/32];
         int last_router;