Changeset 1395

Timestamp:

Jun 27, 2007 12:52:35 PM (17 years ago)

Author:

bennylp

Message:

Ticket #346: deadlock in event subscription when SUBSCRIBE is followed immediately with UN-SUBSCRIBE

File:

• pjproject/trunk/pjsip/src/pjsip-simple/evsub.c (modified) (4 diffs)

pjproject/trunk/pjsip/src/pjsip-simple/evsub.c

@@ -1210 +1210 @@
 }
 
+
+/* Callback to be called to terminate transaction. */
+static void terminate_timer_cb(pj_timer_heap_t *timer_heap,
+                               struct pj_timer_entry *entry)
+{
+    pj_str_t *key;
+    pjsip_transaction *tsx;
+
+    PJ_UNUSED_ARG(timer_heap);
+
+    key = (pj_str_t*)entry->user_data;
+    tsx = pjsip_tsx_layer_find_tsx(key, PJ_FALSE);
+    /* Chance of race condition here */
+    if (tsx) {
+        pjsip_tsx_terminate(tsx, PJSIP_SC_REQUEST_UPDATED);
+    }
+}
 
 
@@ -1376 +1393 @@
             sub->pending_sub->state < PJSIP_TSX_STATE_COMPLETED) 
         {
+            pj_timer_entry *timer;
+            pj_str_t *key;
+            pj_time_val timeout = {0, 0};
+
             PJ_LOG(4,(sub->obj_name, 
                       "Cancelling pending subscription request"));
@@ -1383 +1404 @@
              * will ignore the transaction.
              */
-            pjsip_tsx_terminate(sub->pending_sub, PJSIP_SC_REQUEST_UPDATED);
+            /* This unfortunately may cause deadlock, because at the moment
+             * we are holding dialog's mutex. If a response to this
+             * transaction is in progress in another thread, that thread
+             * will deadlock when trying to acquire dialog mutex, because
+             * it is holding the transaction mutex.
+             *
+             * So the solution is to register timer to kill this transaction.
+             */
+            //pjsip_tsx_terminate(sub->pending_sub, PJSIP_SC_REQUEST_UPDATED);
+            timer = PJ_POOL_ZALLOC_T(dlg->pool, pj_timer_entry);
+            key = PJ_POOL_ALLOC_T(dlg->pool, pj_str_t);
+            pj_strdup(dlg->pool, key, &sub->pending_sub->transaction_key);
+            timer->cb = &terminate_timer_cb;
+            timer->user_data = key;
+
+            pjsip_endpt_schedule_timer(dlg->endpt, timer, &timeout);
         }
 
@@ -1500 +1536 @@
 
         /* Clear pending subscription */
-        if (tsx == sub->pending_sub)
+        if (tsx == sub->pending_sub) {
             sub->pending_sub = NULL;
+        } else if (sub->pending_sub != NULL) {
+            /* This SUBSCRIBE transaction has been "renewed" with another
+             * SUBSCRIBE, so we can just ignore this. For example, user
+             * sent SUBSCRIBE followed immediately with UN-SUBSCRIBE.
+             */
+            return;
+        }
 
         /* Handle authentication. */