Hold lock for three-way channel (bug #2107)

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@3505 65c4cc65-6c06-0410-ace0-fbb531ad65f3

diff --git a/channels/chan_zap.c b/channels/chan_zap.c
index 298708f..7d51979 100755 (executable)
--- a/channels/chan_zap.c
+++ b/channels/chan_zap.c
@@ -3166,6 +3166,27 @@ static struct ast_frame *zt_handle_event(struct ast_channel *ast)
                                        } else if (p->subs[SUB_THREEWAY].owner) {
                                                struct timeval tv;
                                                unsigned int mssinceflash;
+                                               /* Here we have to retain the lock on both the main channel, the 3-way channel, and
+                                                  the private structure -- not especially easy or clean */
+                                               while(p->subs[SUB_THREEWAY].owner && ast_mutex_trylock(&p->subs[SUB_THREEWAY].owner->lock)) {
+                                                       /* Yuck, didn't get the lock on the 3-way, gotta release everything and re-grab! */
+                                                       ast_mutex_unlock(&p->lock);
+                                                       ast_mutex_unlock(&ast->lock);
+                                                       usleep(1);
+                                                       /* We can grab ast and p in that order, without worry.  We should make sure
+                                                          nothing seriously bad has happened though like some sort of bizarre double
+                                                          masquerade! */
+                                                       ast_mutex_lock(&ast->lock);
+                                                       ast_mutex_lock(&p->lock);
+                                                       if (p->owner != ast) {
+                                                               ast_log(LOG_WARNING, "This isn't good...\n");
+                                                               return NULL;
+                                                       }
+                                               }
+                                               if (p->subs[SUB_THREEWAY].owner) {
+                                                       ast_log(LOG_NOTICE, "Whoa, threeway disappeared kinda randomly.\n");
+                                                       return NULL;
+                                               }
                                                gettimeofday(&tv, NULL);
                                                mssinceflash = (tv.tv_sec - p->flashtime.tv_sec) * 1000 + (tv.tv_usec - p->flashtime.tv_usec) / 1000;
                                                ast_log(LOG_DEBUG, "Last flash was %d ms ago\n", mssinceflash);
@@ -3176,6 +3197,7 @@ static struct ast_frame *zt_handle_event(struct ast_channel *ast)
                                                                ast_queue_hangup(p->subs[SUB_THREEWAY].owner);
                                                        p->subs[SUB_THREEWAY].owner->_softhangup |= AST_SOFTHANGUP_DEV;
                                                        ast_log(LOG_DEBUG, "Looks like a bounced flash, hanging up both calls on %d\n", p->channel);
+                                                       ast_mutex_unlock(&p->subs[SUB_THREEWAY].owner->lock);
                                                } else if ((ast->pbx) ||
                                                        (ast->_state == AST_STATE_UP)) {
                                                        if (p->transfer) {
@@ -3186,11 +3208,14 @@ static struct ast_frame *zt_handle_event(struct ast_channel *ast)
                                                                        p->subs[SUB_THREEWAY].owner->_softhangup |= AST_SOFTHANGUP_DEV;
                                                                else if (res) {
                                                                        /* Don't actually hang up at this point */
+                                                                       ast_mutex_unlock(&p->subs[SUB_THREEWAY].owner->lock);
                                                                        break;
                                                                }
                                                        } else
                                                                p->subs[SUB_THREEWAY].owner->_softhangup |= AST_SOFTHANGUP_DEV;
+                                                       ast_mutex_unlock(&p->subs[SUB_THREEWAY].owner->lock);
                                                } else {
+                                                       ast_mutex_unlock(&p->subs[SUB_THREEWAY].owner->lock);
                                                        /* Swap subs and dis-own channel */
                                                        swap_subs(p, SUB_THREEWAY, SUB_REAL);
                                                        p->owner = NULL;