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

diff --git a/main/channel.c b/main/channel.c
index 1ffa0641613916d56b93061a1779e3f2217b6a6f..0ae9af4b0f184e52970ad2ce7548a3a94de88b89 100644 (file)
--- 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);