From: Russell Bryant Date: Tue, 25 Jul 2006 19:51:31 +0000 (+0000) Subject: This exact deadlock situation that I observed can't happen in trunk due to the X-Git-Tag: 1.4.0-beta1~520 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=d86d8ebdffa833fea2b46212bb05752662233b61;p=thirdparty%2Fasterisk.git This exact deadlock situation that I observed can't happen in trunk due to the recent hold changes so that MOH is not started on the bridged channel directly. However, the change is still not a bad idea. Merged revisions 38200 via svnmerge from https://origsvn.digium.com/svn/asterisk/branches/1.2 ........ r38200 | russell | 2006-07-25 15:43:38 -0400 (Tue, 25 Jul 2006) | 6 lines This resolves a deadlock that a tech support customer was getting frequently when his users would answer call waiting. If another thread is currently holding the zt_pvt lock for the first channel, unlock both channels and let asterisk retry the native bridge, just like what is done for the second channel directly below these changes. ........ git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@38201 65c4cc65-6c06-0410-ace0-fbb531ad65f3 --- diff --git a/channels/chan_zap.c b/channels/chan_zap.c index 3aa84d0064..b0578e7769 100644 --- a/channels/chan_zap.c +++ b/channels/chan_zap.c @@ -3117,7 +3117,13 @@ static enum ast_bridge_result zt_bridge(struct ast_channel *c0, struct ast_chann oc0 = p0->owner; oc1 = p1->owner; - ast_mutex_lock(&p0->lock); + if (ast_mutex_trylock(&p0->lock)) { + /* Don't block, due to potential for deadlock */ + ast_mutex_unlock(&c0->lock); + ast_mutex_unlock(&c1->lock); + ast_log(LOG_NOTICE, "Avoiding deadlock...\n"); + return AST_BRIDGE_RETRY; + } if (ast_mutex_trylock(&p1->lock)) { /* Don't block, due to potential for deadlock */ ast_mutex_unlock(&p0->lock);