rstp: Fix global transitions.

Global transitions are highest priority transitions.  When the
condition associated with a global transition is met, it supersedes
all other exit conditions including UCT.

Extracted from 802.1D-2004 standard (17.16):

A transition that is global in nature (i.e., a transition that occurs
from any of the possible states if the condition attached to the arrow
is met) is denoted by an open arrow, i.e., no specific state is
identified as the origin of the transition.  When the condition
associated with a global transition is met, it supersedes all other
exit conditions including UCT.  The special global condition BEGIN
supersedes all other global conditions, and once asserted remains
asserted until all state blocks have executed to the point that
variable assignments and other consequences of their execution remain
unchanged.

Signed-off-by: Daniele Venturino <daniele.venturino@m3s.it>
Acked-by: Jarno Rajahalme <jrajahalme@nicira.com>

diff --git a/lib/rstp-state-machines.c b/lib/rstp-state-machines.c
index 02e3f98..ab3443e 100644 (file)
--- a/lib/rstp-state-machines.c
+++ b/lib/rstp-state-machines.c
@@ -521,7 +521,11 @@ port_receive_sm(struct rstp_port *p)
         p->port_receive_sm_state = PORT_RECEIVE_SM_DISCARD;
         /* no break */
     case PORT_RECEIVE_SM_DISCARD:
-        if (p->rcvd_bpdu && p->port_enabled) {
+        if ((p->rcvd_bpdu || (p->edge_delay_while != r->migrate_time))
+            && !p->port_enabled) {
+            /* Global transition. */
+            p->port_receive_sm_state = PORT_RECEIVE_SM_DISCARD_EXEC;
+        } else if (p->rcvd_bpdu && p->port_enabled) {
             p->port_receive_sm_state = PORT_RECEIVE_SM_RECEIVE_EXEC;
         }
         break;
@@ -533,7 +537,11 @@ port_receive_sm(struct rstp_port *p)
         p->port_receive_sm_state = PORT_RECEIVE_SM_RECEIVE;
         /* no break */
     case PORT_RECEIVE_SM_RECEIVE:
-        if (p->rcvd_bpdu && p->port_enabled && !p->rcvd_msg) {
+        if ((p->rcvd_bpdu || (p->edge_delay_while != r->migrate_time))
+            && !p->port_enabled) {
+            /* Global transition. */
+            p->port_receive_sm_state = PORT_RECEIVE_SM_DISCARD_EXEC;
+        } else if (p->rcvd_bpdu && p->port_enabled && !p->rcvd_msg) {
             p->port_receive_sm_state = PORT_RECEIVE_SM_RECEIVE_EXEC;
         }
         break;
@@ -1130,12 +1138,10 @@ port_information_sm(struct rstp_port *p)
     old_state = p->port_information_sm_state;
     r = p->rstp;
 
-    if (!p->port_enabled && p->info_is != INFO_IS_DISABLED) {
-        p->port_information_sm_state = PORT_INFORMATION_SM_DISABLED_EXEC;
-    }
     switch (p->port_information_sm_state) {
     case PORT_INFORMATION_SM_INIT:
-        if (r->begin) {
+        if (r->begin
+            || (!p->port_enabled && p->info_is != INFO_IS_DISABLED)) {
             p->port_information_sm_state = PORT_INFORMATION_SM_DISABLED_EXEC;
         }
         break;
@@ -1149,7 +1155,10 @@ port_information_sm(struct rstp_port *p)
         p->port_information_sm_state = PORT_INFORMATION_SM_DISABLED;
         /* no break */
     case PORT_INFORMATION_SM_DISABLED:
-        if (p->port_enabled) {
+        if (!p->port_enabled && p->info_is != INFO_IS_DISABLED) {
+            /* Global transition. */
+            p->port_information_sm_state = PORT_INFORMATION_SM_DISABLED_EXEC;
+        } else if (p->port_enabled) {
             p->port_information_sm_state = PORT_INFORMATION_SM_AGED_EXEC;
         } else if (p->rcvd_msg) {
             p->port_information_sm_state = PORT_INFORMATION_SM_DISABLED_EXEC;
@@ -1162,7 +1171,10 @@ port_information_sm(struct rstp_port *p)
         p->port_information_sm_state = PORT_INFORMATION_SM_AGED;
         /* no break */
     case PORT_INFORMATION_SM_AGED:
-        if (p->selected && p->updt_info) {
+        if (!p->port_enabled && p->info_is != INFO_IS_DISABLED) {
+            /* Global transition. */
+            p->port_information_sm_state = PORT_INFORMATION_SM_DISABLED_EXEC;
+        } else if (p->selected && p->updt_info) {
             p->port_information_sm_state = PORT_INFORMATION_SM_UPDATE_EXEC;
         }
         break;
@@ -1186,13 +1198,21 @@ port_information_sm(struct rstp_port *p)
         p->port_information_sm_state = PORT_INFORMATION_SM_UPDATE;
         /* no break */
     case PORT_INFORMATION_SM_UPDATE:
-        p->port_information_sm_state = PORT_INFORMATION_SM_CURRENT_EXEC;
+        if (!p->port_enabled && p->info_is != INFO_IS_DISABLED) {
+            /* Global transition. */
+            p->port_information_sm_state = PORT_INFORMATION_SM_DISABLED_EXEC;
+        } else {
+            p->port_information_sm_state = PORT_INFORMATION_SM_CURRENT_EXEC;
+        }
         break;
     case PORT_INFORMATION_SM_CURRENT_EXEC:
         p->port_information_sm_state = PORT_INFORMATION_SM_CURRENT;
         /* no break */
     case PORT_INFORMATION_SM_CURRENT:
-        if (p->rcvd_msg && !p->updt_info) {
+        if (!p->port_enabled && p->info_is != INFO_IS_DISABLED) {
+            /* Global transition. */
+            p->port_information_sm_state = PORT_INFORMATION_SM_DISABLED_EXEC;
+        } else if (p->rcvd_msg && !p->updt_info) {
             p->port_information_sm_state = PORT_INFORMATION_SM_RECEIVE_EXEC;
         } else if (p->selected && p->updt_info) {
             p->port_information_sm_state = PORT_INFORMATION_SM_UPDATE_EXEC;
@@ -1207,29 +1227,34 @@ port_information_sm(struct rstp_port *p)
         p->port_information_sm_state = PORT_INFORMATION_SM_RECEIVE;
         /* no break */
     case PORT_INFORMATION_SM_RECEIVE:
-        switch (p->rcvd_info) {
-        case SUPERIOR_DESIGNATED_INFO:
-            p->port_information_sm_state =
-                PORT_INFORMATION_SM_SUPERIOR_DESIGNATED_EXEC;
-            break;
-        case REPEATED_DESIGNATED_INFO:
-            p->port_information_sm_state =
-                PORT_INFORMATION_SM_REPEATED_DESIGNATED_EXEC;
-            break;
-        case INFERIOR_DESIGNATED_INFO:
-            p->port_information_sm_state =
-                PORT_INFORMATION_SM_INFERIOR_DESIGNATED_EXEC;
-            break;
-        case INFERIOR_ROOT_ALTERNATE_INFO:
-            p->port_information_sm_state =
-                PORT_INFORMATION_SM_NOT_DESIGNATED_EXEC;
-            break;
-        case OTHER_INFO:
-            p->port_information_sm_state = PORT_INFORMATION_SM_OTHER_EXEC;
-            break;
-        default:
-            OVS_NOT_REACHED();
-            /* no break */
+        if (!p->port_enabled && p->info_is != INFO_IS_DISABLED) {
+            /* Global transition. */
+            p->port_information_sm_state = PORT_INFORMATION_SM_DISABLED_EXEC;
+        } else {
+            switch (p->rcvd_info) {
+            case SUPERIOR_DESIGNATED_INFO:
+                p->port_information_sm_state =
+                    PORT_INFORMATION_SM_SUPERIOR_DESIGNATED_EXEC;
+                break;
+            case REPEATED_DESIGNATED_INFO:
+                p->port_information_sm_state =
+                    PORT_INFORMATION_SM_REPEATED_DESIGNATED_EXEC;
+                break;
+            case INFERIOR_DESIGNATED_INFO:
+                p->port_information_sm_state =
+                    PORT_INFORMATION_SM_INFERIOR_DESIGNATED_EXEC;
+                break;
+            case INFERIOR_ROOT_ALTERNATE_INFO:
+                p->port_information_sm_state =
+                    PORT_INFORMATION_SM_NOT_DESIGNATED_EXEC;
+                break;
+            case OTHER_INFO:
+                p->port_information_sm_state = PORT_INFORMATION_SM_OTHER_EXEC;
+                break;
+            default:
+                OVS_NOT_REACHED();
+                /* no break */
+            }
         }
         break;
     case PORT_INFORMATION_SM_OTHER_EXEC:
@@ -1237,7 +1262,12 @@ port_information_sm(struct rstp_port *p)
         p->port_information_sm_state = PORT_INFORMATION_SM_OTHER;
         /* no break */
     case PORT_INFORMATION_SM_OTHER:
-        p->port_information_sm_state = PORT_INFORMATION_SM_CURRENT_EXEC;
+        if (!p->port_enabled && p->info_is != INFO_IS_DISABLED) {
+            /* Global transition. */
+            p->port_information_sm_state = PORT_INFORMATION_SM_DISABLED_EXEC;
+        } else {
+            p->port_information_sm_state = PORT_INFORMATION_SM_CURRENT_EXEC;
+        }
         break;
     case PORT_INFORMATION_SM_NOT_DESIGNATED_EXEC:
         record_agreement(p);
@@ -1246,7 +1276,12 @@ port_information_sm(struct rstp_port *p)
         p->port_information_sm_state = PORT_INFORMATION_SM_NOT_DESIGNATED;
         /* no break */
     case PORT_INFORMATION_SM_NOT_DESIGNATED:
-        p->port_information_sm_state = PORT_INFORMATION_SM_CURRENT_EXEC;
+        if (!p->port_enabled && p->info_is != INFO_IS_DISABLED) {
+            /* Global transition. */
+            p->port_information_sm_state = PORT_INFORMATION_SM_DISABLED_EXEC;
+        } else {
+            p->port_information_sm_state = PORT_INFORMATION_SM_CURRENT_EXEC;
+        }
         break;
     case PORT_INFORMATION_SM_INFERIOR_DESIGNATED_EXEC:
         record_dispute(p);
@@ -1254,7 +1289,12 @@ port_information_sm(struct rstp_port *p)
         p->port_information_sm_state = PORT_INFORMATION_SM_INFERIOR_DESIGNATED;
         /* no break */
     case PORT_INFORMATION_SM_INFERIOR_DESIGNATED:
-        p->port_information_sm_state = PORT_INFORMATION_SM_CURRENT_EXEC;
+        if (!p->port_enabled && p->info_is != INFO_IS_DISABLED) {
+            /* Global transition. */
+            p->port_information_sm_state = PORT_INFORMATION_SM_DISABLED_EXEC;
+        } else {
+            p->port_information_sm_state = PORT_INFORMATION_SM_CURRENT_EXEC;
+        }
         break;
     case PORT_INFORMATION_SM_REPEATED_DESIGNATED_EXEC:
         record_proposal(p);
@@ -1264,7 +1304,12 @@ port_information_sm(struct rstp_port *p)
         p->port_information_sm_state = PORT_INFORMATION_SM_REPEATED_DESIGNATED;
         /* no break */
     case PORT_INFORMATION_SM_REPEATED_DESIGNATED:
-        p->port_information_sm_state = PORT_INFORMATION_SM_CURRENT_EXEC;
+        if (!p->port_enabled && p->info_is != INFO_IS_DISABLED) {
+            /* Global transition. */
+            p->port_information_sm_state = PORT_INFORMATION_SM_DISABLED_EXEC;
+        } else {
+            p->port_information_sm_state = PORT_INFORMATION_SM_CURRENT_EXEC;
+        }
         break;
     case PORT_INFORMATION_SM_SUPERIOR_DESIGNATED_EXEC:
         p->agreed = p->proposing = false;
@@ -1282,7 +1327,12 @@ port_information_sm(struct rstp_port *p)
         p->port_information_sm_state = PORT_INFORMATION_SM_SUPERIOR_DESIGNATED;
         /* no break */
     case PORT_INFORMATION_SM_SUPERIOR_DESIGNATED:
-        p->port_information_sm_state = PORT_INFORMATION_SM_CURRENT_EXEC;
+        if (!p->port_enabled && p->info_is != INFO_IS_DISABLED) {
+            /* Global transition. */
+            p->port_information_sm_state = PORT_INFORMATION_SM_DISABLED_EXEC;
+        } else {
+            p->port_information_sm_state = PORT_INFORMATION_SM_CURRENT_EXEC;
+        }
         break;
     default:
         OVS_NOT_REACHED();
@@ -1468,7 +1518,7 @@ port_role_transition_sm(struct rstp_port *p)
         /* no break */
     case PORT_ROLE_TRANSITION_SM_DISABLE_PORT:
         if (check_selected_role_change(p, ROLE_DISABLED)) {
-            break;
+            /* Global transition. */
         } else if (p->selected && !p->updt_info && !p->learning
                    && !p->forwarding) {
             p->port_role_transition_sm_state =
@@ -1485,7 +1535,7 @@ port_role_transition_sm(struct rstp_port *p)
         /* no break */
     case PORT_ROLE_TRANSITION_SM_DISABLED_PORT:
         if (check_selected_role_change(p, ROLE_DISABLED)) {
-            break;
+            /* Global transition. */
         } else if (p->selected && !p->updt_info
                    && (p->fd_while != p->designated_times.max_age || p->sync
                        || p->re_root || !p->synced)) {
@@ -1500,7 +1550,7 @@ port_role_transition_sm(struct rstp_port *p)
         /* no break */
     case PORT_ROLE_TRANSITION_SM_ROOT_PORT:
         if (check_selected_role_change(p, ROLE_ROOT)) {
-            break;
+            /* Global transition. */
         } else if (p->selected && !p->updt_info) {
             if (p->rr_while != p->designated_times.forward_delay) {
                 p->port_role_transition_sm_state =
@@ -1537,40 +1587,64 @@ port_role_transition_sm(struct rstp_port *p)
                 break;
             }
         }
-    break;
+        break;
     case PORT_ROLE_TRANSITION_SM_REROOT_EXEC:
-        set_re_root_tree(p);
-        p->port_role_transition_sm_state =
-            PORT_ROLE_TRANSITION_SM_ROOT_PORT_EXEC;
+        if (check_selected_role_change(p, ROLE_ROOT)) {
+            /* Global transition. */
+        } else {
+            set_re_root_tree(p);
+            p->port_role_transition_sm_state =
+                PORT_ROLE_TRANSITION_SM_ROOT_PORT_EXEC;
+        }
         break;
     case PORT_ROLE_TRANSITION_SM_ROOT_AGREED_EXEC:
-        p->proposed = p->sync = false;
-        p->agree = p->new_info = true;
-        p->port_role_transition_sm_state =
-            PORT_ROLE_TRANSITION_SM_ROOT_PORT_EXEC;
+        if (check_selected_role_change(p, ROLE_ROOT)) {
+            /* Global transition. */
+        } else {
+            p->proposed = p->sync = false;
+            p->agree = p->new_info = true;
+            p->port_role_transition_sm_state =
+                PORT_ROLE_TRANSITION_SM_ROOT_PORT_EXEC;
+        }
         break;
     case PORT_ROLE_TRANSITION_SM_ROOT_PROPOSED_EXEC:
         set_sync_tree(p);
         p->proposed = false;
-        p->port_role_transition_sm_state =
-            PORT_ROLE_TRANSITION_SM_ROOT_PORT_EXEC;
+        if (check_selected_role_change(p, ROLE_ROOT)) {
+            /* Global transition. */
+        } else {
+            p->port_role_transition_sm_state =
+                PORT_ROLE_TRANSITION_SM_ROOT_PORT_EXEC;
+        }
         break;
     case PORT_ROLE_TRANSITION_SM_ROOT_FORWARD_EXEC:
         p->fd_while = 0;
         p->forward = true;
-        p->port_role_transition_sm_state =
-            PORT_ROLE_TRANSITION_SM_ROOT_PORT_EXEC;
+        if (check_selected_role_change(p, ROLE_ROOT)) {
+            /* Global transition. */
+        } else {
+            p->port_role_transition_sm_state =
+                PORT_ROLE_TRANSITION_SM_ROOT_PORT_EXEC;
+        }
         break;
     case PORT_ROLE_TRANSITION_SM_ROOT_LEARN_EXEC:
         p->fd_while = forward_delay(p);
         p->learn = true;
-        p->port_role_transition_sm_state =
-            PORT_ROLE_TRANSITION_SM_ROOT_PORT_EXEC;
+        if (check_selected_role_change(p, ROLE_ROOT)) {
+            /* Global transition. */
+        } else {
+            p->port_role_transition_sm_state =
+                PORT_ROLE_TRANSITION_SM_ROOT_PORT_EXEC;
+        }
         break;
     case PORT_ROLE_TRANSITION_SM_REROOTED_EXEC:
         p->re_root = false;
-        p->port_role_transition_sm_state =
-            PORT_ROLE_TRANSITION_SM_ROOT_PORT_EXEC;
+        if (check_selected_role_change(p, ROLE_ROOT)) {
+            /* Global transition. */
+        } else {
+            p->port_role_transition_sm_state =
+                PORT_ROLE_TRANSITION_SM_ROOT_PORT_EXEC;
+        }
         break;
     case PORT_ROLE_TRANSITION_SM_DESIGNATED_PORT_EXEC:
         p->role = ROLE_DESIGNATED;
@@ -1579,7 +1653,7 @@ port_role_transition_sm(struct rstp_port *p)
         /* no break */
     case PORT_ROLE_TRANSITION_SM_DESIGNATED_PORT:
         if (check_selected_role_change(p, ROLE_DESIGNATED)) {
-            break;
+            /* Global transition. */
         } else if (p->selected && !p->updt_info) {
             if (((p->sync && !p->synced)
                  || (p->re_root && p->rr_while != 0) || p->disputed)
@@ -1614,41 +1688,65 @@ port_role_transition_sm(struct rstp_port *p)
         break;
     case PORT_ROLE_TRANSITION_SM_DESIGNATED_RETIRED_EXEC:
         p->re_root = false;
-        p->port_role_transition_sm_state =
-            PORT_ROLE_TRANSITION_SM_DESIGNATED_PORT_EXEC;
+        if (check_selected_role_change(p, ROLE_DESIGNATED)) {
+            /* Global transition. */
+        } else {
+            p->port_role_transition_sm_state =
+                PORT_ROLE_TRANSITION_SM_DESIGNATED_PORT_EXEC;
+        }
         break;
     case PORT_ROLE_TRANSITION_SM_DESIGNATED_SYNCED_EXEC:
         p->rr_while = 0;
         p->synced = true;
         p->sync = false;
-        p->port_role_transition_sm_state =
-            PORT_ROLE_TRANSITION_SM_DESIGNATED_PORT_EXEC;
+        if (check_selected_role_change(p, ROLE_DESIGNATED)) {
+            /* Global transition. */
+        } else {
+            p->port_role_transition_sm_state =
+                PORT_ROLE_TRANSITION_SM_DESIGNATED_PORT_EXEC;
+        }
         break;
     case PORT_ROLE_TRANSITION_SM_DESIGNATED_PROPOSE_EXEC:
         p->proposing = true;
         p->edge_delay_while = edge_delay(p);
         p->new_info = true;
-        p->port_role_transition_sm_state =
-            PORT_ROLE_TRANSITION_SM_DESIGNATED_PORT_EXEC;
+        if (check_selected_role_change(p, ROLE_DESIGNATED)) {
+            /* Global transition. */
+        } else {
+            p->port_role_transition_sm_state =
+                PORT_ROLE_TRANSITION_SM_DESIGNATED_PORT_EXEC;
+        }
         break;
     case PORT_ROLE_TRANSITION_SM_DESIGNATED_FORWARD_EXEC:
         p->forward = true;
         p->fd_while = 0;
         p->agreed = p->send_rstp;
-        p->port_role_transition_sm_state =
-            PORT_ROLE_TRANSITION_SM_DESIGNATED_PORT_EXEC;
+        if (check_selected_role_change(p, ROLE_DESIGNATED)) {
+            /* Global transition. */
+        } else {
+            p->port_role_transition_sm_state =
+                PORT_ROLE_TRANSITION_SM_DESIGNATED_PORT_EXEC;
+        }
         break;
     case PORT_ROLE_TRANSITION_SM_DESIGNATED_LEARN_EXEC:
         p->learn = true;
         p->fd_while = forward_delay(p);
-        p->port_role_transition_sm_state =
-            PORT_ROLE_TRANSITION_SM_DESIGNATED_PORT_EXEC;
+        if (check_selected_role_change(p, ROLE_DESIGNATED)) {
+            /* Global transition. */
+        } else {
+            p->port_role_transition_sm_state =
+                PORT_ROLE_TRANSITION_SM_DESIGNATED_PORT_EXEC;
+        }
         break;
     case PORT_ROLE_TRANSITION_SM_DESIGNATED_DISCARD_EXEC:
         p->learn = p->forward = p->disputed = false;
         p->fd_while = forward_delay(p);
-        p->port_role_transition_sm_state =
-            PORT_ROLE_TRANSITION_SM_DESIGNATED_PORT_EXEC;
+        if (check_selected_role_change(p, ROLE_DESIGNATED)) {
+            /* Global transition. */
+        } else {
+            p->port_role_transition_sm_state =
+                PORT_ROLE_TRANSITION_SM_DESIGNATED_PORT_EXEC;
+        }
         break;
     case PORT_ROLE_TRANSITION_SM_ALTERNATE_PORT_EXEC:
         p->fd_while = p->designated_times.forward_delay;
@@ -1660,7 +1758,7 @@ port_role_transition_sm(struct rstp_port *p)
         /* no break */
     case PORT_ROLE_TRANSITION_SM_ALTERNATE_PORT:
         if (check_selected_role_change(p, ROLE_ALTERNATE)) {
-            break;
+            /* Global transition. */
         } else if (p->selected && !p->updt_info) {
             if (p->rb_while != 2 * p->designated_times.hello_time
                 && p->role == ROLE_BACKUP) {
@@ -1684,14 +1782,22 @@ port_role_transition_sm(struct rstp_port *p)
         p->proposed = false;
         p->agree = true;
         p->new_info = true;
-        p->port_role_transition_sm_state =
-            PORT_ROLE_TRANSITION_SM_ALTERNATE_PORT_EXEC;
+        if (check_selected_role_change(p, ROLE_ALTERNATE)) {
+            /* Global transition. */
+        } else {
+            p->port_role_transition_sm_state =
+                PORT_ROLE_TRANSITION_SM_ALTERNATE_PORT_EXEC;
+        }
         break;
     case PORT_ROLE_TRANSITION_SM_ALTERNATE_PROPOSED_EXEC:
         set_sync_tree(p);
         p->proposed = false;
-        p->port_role_transition_sm_state =
-            PORT_ROLE_TRANSITION_SM_ALTERNATE_PORT_EXEC;
+        if (check_selected_role_change(p, ROLE_ALTERNATE)) {
+            /* Global transition. */
+        } else {
+            p->port_role_transition_sm_state =
+                PORT_ROLE_TRANSITION_SM_ALTERNATE_PORT_EXEC;
+        }
         break;
     case PORT_ROLE_TRANSITION_SM_BLOCK_PORT_EXEC:
         p->role = p->selected_role;
@@ -1700,7 +1806,7 @@ port_role_transition_sm(struct rstp_port *p)
         /* no break */
     case PORT_ROLE_TRANSITION_SM_BLOCK_PORT:
         if (check_selected_role_change(p, ROLE_ALTERNATE)) {
-            break;
+            /* Global transition. */
         } else if (p->selected && !p->updt_info && !p->learning &&
                    !p->forwarding) {
             p->port_role_transition_sm_state =
@@ -1709,8 +1815,12 @@ port_role_transition_sm(struct rstp_port *p)
         break;
     case PORT_ROLE_TRANSITION_SM_BACKUP_PORT_EXEC:
         p->rb_while = 2 * p->designated_times.hello_time;
-        p->port_role_transition_sm_state =
-            PORT_ROLE_TRANSITION_SM_ALTERNATE_PORT_EXEC;
+        if (check_selected_role_change(p, ROLE_ALTERNATE)) {
+            /* Global transition. */
+        } else {
+            p->port_role_transition_sm_state =
+                PORT_ROLE_TRANSITION_SM_ALTERNATE_PORT_EXEC;
+        }
         break;
     default:
         OVS_NOT_REACHED();