Merged revisions 84049 via svnmerge from
authorTilghman Lesher <tilghman@meg.abyt.es>
Fri, 28 Sep 2007 05:37:16 +0000 (05:37 +0000)
committerTilghman Lesher <tilghman@meg.abyt.es>
Fri, 28 Sep 2007 05:37:16 +0000 (05:37 +0000)
https://origsvn.digium.com/svn/asterisk/branches/1.4

........
r84049 | tilghman | 2007-09-28 00:30:22 -0500 (Fri, 28 Sep 2007) | 3 lines

Avoid a deadlock with ALL of the locks in the masquerade function, not just the
pairs of channels.  (Closes issue #10406)

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git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@84050 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/channel.c

index d8a137e..e11afe9 100644 (file)
@@ -3333,7 +3333,11 @@ 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)) {
@@ -3351,11 +3355,19 @@ 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);