ipcpd: Prevent parallel DHT enrollment threads

This will prevent quick calls to ipcp conn for dt flows to create
multiple join threads in parallel, instead the subsequent calls will
wait for the pending join to finish.

Signed-off-by: Dimitri Staessens <dimitri.staessens@ugent.be>
Signed-off-by: Sander Vrijders <sander.vrijders@ugent.be>

1 files changed, 24 insertions, 22 deletions

diff --git a/src/ipcpd/normal/dht.c b/src/ipcpd/normal/dht.c
index 1e96c94a..1fabcb84 100644
--- a/src/ipcpd/normal/dht.c
+++ b/src/ipcpd/normal/dht.c
@@ -276,16 +276,23 @@ static enum dht_state dht_get_state(struct dht * dht)
         return state;
 }
 
-static void dht_set_state(struct dht *   dht,
-                          enum dht_state state)
+static int dht_set_state(struct dht *   dht,
+                         enum dht_state state)
 {
         pthread_mutex_lock(&dht->mtx);
 
+        if (state == DHT_JOINING && dht->state != DHT_INIT) {
+                 pthread_mutex_unlock(&dht->mtx);
+                 return -1;
+        }
+
         dht->state = state;
 
         pthread_cond_broadcast(&dht->cond);
 
         pthread_mutex_unlock(&dht->mtx);
+
+        return 0;
 }
 
 static int dht_wait_running(struct dht * dht)
@@ -2282,9 +2289,6 @@ int dht_reg(struct dht *    dht,
         assert(key);
         assert(dht->addr != 0);
 
-        if (dht_get_state(dht) < DHT_JOINING)
-                return -1;
-
         if (dht_wait_running(dht))
                 return -1;
 
@@ -2353,9 +2357,6 @@ uint64_t dht_query(struct dht *    dht,
 
         addrs[0] = 0;
 
-        if (dht_get_state(dht) < DHT_JOINING)
-                return 0;
-
         if (dht_wait_running(dht))
                 return 0;
 
@@ -2715,27 +2716,28 @@ static void handle_event(void *       self,
 
         if (event == NOTIFY_DT_CONN_ADD) {
                 pthread_t          thr;
-                struct join_info * info;
+                struct join_info * inf;
                 struct conn *      c     = (struct conn *) o;
-                enum dht_state     state = dht_get_state(dht);
 
-                switch(state) {
+                switch(dht_get_state(dht)) {
                 case DHT_INIT:
-                        info = malloc(sizeof(*info));
-                        if (info == NULL)
+                        inf = malloc(sizeof(*inf));
+                        if (inf == NULL)
                                 break;
 
-                        info->dht  = dht;
-                        info->addr = c->conn_info.addr;
+                        inf->dht  = dht;
+                        inf->addr = c->conn_info.addr;
 
-                        dht_set_state(dht, DHT_JOINING);
-
-                        if (pthread_create(&thr, NULL, join_thr, info)) {
-                                dht_set_state(dht, DHT_INIT);
-                                free(info);
-                                return;
+                        if (dht_set_state(dht, DHT_JOINING) == 0 ||
+                            dht_wait_running(dht)) {
+                                log_dbg("creating join thread.");
+                                if (pthread_create(&thr, NULL, join_thr, inf)) {
+                                        dht_set_state(dht, DHT_INIT);
+                                        free(inf);
+                                        return;
+                                }
+                                pthread_detach(thr);
                         }
-                        pthread_detach(thr);
                         break;
                 case DHT_RUNNING:
                         /*