chan_iax2: Fix bridgecallno deadlock avoidance.
authorRichard Mudgett <rmudgett@digium.com>
Thu, 5 Sep 2013 17:17:53 +0000 (17:17 +0000)
committerRichard Mudgett <rmudgett@digium.com>
Thu, 5 Sep 2013 17:17:53 +0000 (17:17 +0000)
* Fix bridgecallno deadlock avoidance.  When doing deadlock avoidance, you
need to retest the status of values for each loop to see if you still need
the lock for bridgecallno.

* As a safety check, after acquiring the bridgecallno lock you should
check if iaxs[bridgecallno] is NULL just like the current callno checks.

* Move setting thread->iostate to IAX_IOSTATE_IDLE to after processing any
deferred frames to ensure that the iostate is IDLE when it is placed back
into the idle list.  defer_full_frame() tries to ensure
iax2_process_thread() wakes up to process the frame.
........

Merged revisions 398379 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 398380 from http://svn.asterisk.org/svn/asterisk/branches/11
........

Merged revisions 398381 from http://svn.asterisk.org/svn/asterisk/branches/12

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@398384 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_iax2.c

index 1984fc7..3069bc9 100644 (file)
@@ -831,7 +831,7 @@ struct chan_iax2_pvt {
        /*! Status of knowledge of peer ADSI capability */
        int peeradsicpe;
 
-       /*! Who we are bridged to */
+       /*! Callno of native bridge peer. (Valid if nonzero) */
        unsigned short bridgecallno;
 
        int pingid;                     /*!< Transmit PING request */
@@ -11221,13 +11221,13 @@ immediatedial:
                                }
                                break;
                        case IAX_COMMAND_TXREJ:
-                               if (iaxs[fr->callno]->bridgecallno) {
-                                       while (ast_mutex_trylock(&iaxsl[iaxs[fr->callno]->bridgecallno])) {
-                                               DEADLOCK_AVOIDANCE(&iaxsl[fr->callno]);
-                                       }
-                                       if (!iaxs[fr->callno]) {
-                                               break;
-                                       }
+                               while (iaxs[fr->callno]
+                                       && iaxs[fr->callno]->bridgecallno
+                                       && ast_mutex_trylock(&iaxsl[iaxs[fr->callno]->bridgecallno])) {
+                                       DEADLOCK_AVOIDANCE(&iaxsl[fr->callno]);
+                               }
+                               if (!iaxs[fr->callno]) {
+                                       break;
                                }
 
                                iaxs[fr->callno]->transferring = TRANSFER_NONE;
@@ -11238,20 +11238,21 @@ immediatedial:
                                        break;
                                }
 
-                               if (iaxs[iaxs[fr->callno]->bridgecallno]->transferring) {
+                               if (iaxs[iaxs[fr->callno]->bridgecallno]
+                                       && iaxs[iaxs[fr->callno]->bridgecallno]->transferring) {
                                        iaxs[iaxs[fr->callno]->bridgecallno]->transferring = TRANSFER_NONE;
                                        send_command(iaxs[iaxs[fr->callno]->bridgecallno], AST_FRAME_IAX, IAX_COMMAND_TXREJ, 0, NULL, 0, -1);
                                }
                                ast_mutex_unlock(&iaxsl[iaxs[fr->callno]->bridgecallno]);
                                break;
                        case IAX_COMMAND_TXREADY:
-                               if (iaxs[fr->callno]->bridgecallno) {
-                                       while (ast_mutex_trylock(&iaxsl[iaxs[fr->callno]->bridgecallno])) {
-                                               DEADLOCK_AVOIDANCE(&iaxsl[fr->callno]);
-                                       }
-                                       if (!iaxs[fr->callno]) {
-                                               break;
-                                       }
+                               while (iaxs[fr->callno]
+                                       && iaxs[fr->callno]->bridgecallno
+                                       && ast_mutex_trylock(&iaxsl[iaxs[fr->callno]->bridgecallno])) {
+                                       DEADLOCK_AVOIDANCE(&iaxsl[fr->callno]);
+                               }
+                               if (!iaxs[fr->callno]) {
+                                       break;
                                }
 
                                if (iaxs[fr->callno]->transferring == TRANSFER_BEGIN) {
@@ -11270,8 +11271,9 @@ immediatedial:
                                        break;
                                }
 
-                               if (!(iaxs[iaxs[fr->callno]->bridgecallno]->transferring == TRANSFER_READY) &&
-                                   !(iaxs[iaxs[fr->callno]->bridgecallno]->transferring == TRANSFER_MREADY)) {
+                               if (!iaxs[iaxs[fr->callno]->bridgecallno]
+                                       || (iaxs[iaxs[fr->callno]->bridgecallno]->transferring != TRANSFER_READY
+                                               && iaxs[iaxs[fr->callno]->bridgecallno]->transferring != TRANSFER_MREADY)) {
                                        ast_mutex_unlock(&iaxsl[iaxs[fr->callno]->bridgecallno]);
                                        break;
                                }
@@ -11655,11 +11657,10 @@ static void *iax2_process_thread(void *data)
                        break;
                }
 
-               if (thread->iostate == IAX_IOSTATE_IDLE)
-                       continue;
-
                /* See what we need to do */
                switch (thread->iostate) {
+               case IAX_IOSTATE_IDLE:
+                       continue;
                case IAX_IOSTATE_READY:
                        thread->actions++;
                        thread->iostate = IAX_IOSTATE_PROCESSING;
@@ -11672,14 +11673,10 @@ static void *iax2_process_thread(void *data)
 #ifdef SCHED_MULTITHREADED
                        thread->schedfunc(thread->scheddata);
 #endif
+                       break;
                default:
                        break;
                }
-               time(&thread->checktime);
-               thread->iostate = IAX_IOSTATE_IDLE;
-#ifdef DEBUG_SCHED_MULTITHREAD
-               thread->curfunc[0]='\0';
-#endif
 
                /* The network thread added us to the active_thread list when we were given
                 * frames to process, Now that we are done, we must remove ourselves from
@@ -11690,6 +11687,12 @@ static void *iax2_process_thread(void *data)
 
                /* Make sure another frame didn't sneak in there after we thought we were done. */
                handle_deferred_full_frames(thread);
+
+               time(&thread->checktime);
+               thread->iostate = IAX_IOSTATE_IDLE;
+#ifdef DEBUG_SCHED_MULTITHREAD
+               thread->curfunc[0]='\0';
+#endif
        }
 
        /*!