From bf8c25677172c0e425bfcfae507289054c995ed5 Mon Sep 17 00:00:00 2001
From: Paul Davis <paul@linuxaudiosystems.com>
Date: Thu, 12 Dec 2019 12:09:15 -0700
Subject: [PATCH] reduce another race condition risk

overwrite_queued == true is equivalent to _pending_overwrite != 0
---
 libs/ardour/ardour/disk_reader.h |  1 -
 libs/ardour/disk_reader.cc       | 10 ++--------
 2 files changed, 2 insertions(+), 9 deletions(-)

diff --git a/libs/ardour/ardour/disk_reader.h b/libs/ardour/ardour/disk_reader.h
index fd437e57ea..725fa4b2ce 100644
--- a/libs/ardour/ardour/disk_reader.h
+++ b/libs/ardour/ardour/disk_reader.h
@@ -184,7 +184,6 @@ private:
 	sampleoffset_t overwrite_offset;
 	samplepos_t   new_file_sample;
 	mutable gint  _pending_overwrite;
-	bool          overwrite_queued;
 	bool          run_must_resolve;
 	IOChange      input_change_pending;
 	samplepos_t   file_sample[DataType::num_types];
diff --git a/libs/ardour/disk_reader.cc b/libs/ardour/disk_reader.cc
index e3cd75f5a1..b085029e54 100644
--- a/libs/ardour/disk_reader.cc
+++ b/libs/ardour/disk_reader.cc
@@ -60,7 +60,6 @@ samplecnt_t DiskReader::loop_fade_length (0);
 DiskReader::DiskReader (Session& s, string const & str, DiskIOProcessor::Flag f)
 	: DiskIOProcessor (s, str, f)
 	, overwrite_sample (0)
-	, overwrite_queued (false)
 	, run_must_resolve (false)
 	, _declick_amp (s.nominal_sample_rate ())
 	, _declick_offs (0)
@@ -233,10 +232,7 @@ DiskReader::adjust_buffering ()
 void
 DiskReader::playlist_modified ()
 {
-	if (!overwrite_queued) {
-		_session.request_overwrite_buffer (_track, PlaylistModified);
-		overwrite_queued = true;
-	}
+	_session.request_overwrite_buffer (_track, PlaylistModified);
 }
 
 int
@@ -257,9 +253,8 @@ DiskReader::use_playlist (DataType dt, boost::shared_ptr<Playlist> playlist)
 	   take care of the buffer refill.
 	*/
 
-        if (!overwrite_queued && (prior_playlist || _session.loading())) {
+        if ((g_atomic_int_get (&_pending_overwrite) & PlaylistChanged) || prior_playlist) {
 	        _session.request_overwrite_buffer (_track, PlaylistChanged);
-		overwrite_queued = true;
 	}
 
 	return 0;
@@ -639,7 +634,6 @@ DiskReader::overwrite_existing_buffers ()
 		}
 	}
 
-	overwrite_queued = false;
 	g_atomic_int_set (&_pending_overwrite, 0);
 
 	return ret;