From c055c55fbc5e7ced38c579424168a7843e659042 Mon Sep 17 00:00:00 2001
From: Arun Raghavan <arun.raghavan@collabora.co.uk>
Date: Tue, 4 Oct 2011 14:06:26 +0530
Subject: [PATCH] echo-cancel: Fail if loaded between a sink and its monitor

Loading between a sink and its monitor causes a deadlock (while sending
messages for latency snapshots). It isn't a case that has any real
conceivable use, so let's just disallow it.
---
 src/modules/echo-cancel/module-echo-cancel.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/modules/echo-cancel/module-echo-cancel.c b/src/modules/echo-cancel/module-echo-cancel.c
index 6c7828f46..89638b733 100644
--- a/src/modules/echo-cancel/module-echo-cancel.c
+++ b/src/modules/echo-cancel/module-echo-cancel.c
@@ -1357,6 +1357,11 @@ int pa__init(pa_module*m) {
     }
     pa_assert(sink_master);
 
+    if (source_master->monitor_of == sink_master) {
+        pa_log("Can't cancel echo between a sink and its monitor");
+        goto fail;
+    }
+
     source_ss = source_master->sample_spec;
     source_ss.rate = DEFAULT_RATE;
     source_ss.channels = DEFAULT_CHANNELS;