From 253a34b756b3c411aa55d1b6b655eaf7b04c24be Mon Sep 17 00:00:00 2001 From: Tilghman Lesher Date: Fri, 28 Sep 2007 05:30:22 +0000 Subject: [PATCH] Avoid a deadlock with ALL of the locks in the masquerade function, not just the pairs of channels. (Closes issue #10406) git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@84049 65c4cc65-6c06-0410-ace0-fbb531ad65f3 --- main/channel.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) diff --git a/main/channel.c b/main/channel.c index 1ffa064161..0ae9af4b0f 100644 --- a/main/channel.c +++ b/main/channel.c @@ -3410,7 +3410,11 @@ int ast_channel_make_compatible(struct ast_channel *chan, struct ast_channel *pe int ast_channel_masquerade(struct ast_channel *original, struct ast_channel *clone) { int res = -1; - struct ast_channel *final_orig = original, *final_clone = clone; + struct ast_channel *final_orig, *final_clone; + +retrymasq: + final_orig = original; + final_clone = clone; ast_channel_lock(original); while (ast_channel_trylock(clone)) { @@ -3428,11 +3432,19 @@ int ast_channel_masquerade(struct ast_channel *original, struct ast_channel *clo final_clone = clone->_bridge; if ((final_orig != original) || (final_clone != clone)) { - ast_channel_lock(final_orig); - while (ast_channel_trylock(final_clone)) { + /* Lots and lots of deadlock avoidance. The main one we're competing with + * is ast_write(), which locks channels recursively, when working with a + * proxy channel. */ + if (ast_channel_trylock(final_orig)) { + ast_channel_unlock(clone); + ast_channel_unlock(original); + goto retrymasq; + } + if (ast_channel_trylock(final_clone)) { ast_channel_unlock(final_orig); - usleep(1); - ast_channel_lock(final_orig); + ast_channel_unlock(clone); + ast_channel_unlock(original); + goto retrymasq; } ast_channel_unlock(clone); ast_channel_unlock(original);