Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 262 insertions, 0 deletions

diff --git a/media/libcubeb/test/test_deadlock.cpp b/media/libcubeb/test/test_deadlock.cpp
new file mode 100644
index 0000000000..373ba6ad7e
--- /dev/null
+++ b/media/libcubeb/test/test_deadlock.cpp
@@ -0,0 +1,262 @@
+/*
+ * Copyright © 2017 Mozilla Foundation
+ *
+ * This program is made available under an ISC-style license.  See the
+ * accompanying file LICENSE for details.
+ *
+ *
+ * Purpose
+ * =============================================================================
+ * In CoreAudio, the data callback will holds a mutex shared with AudioUnit
+ * (mutex_AU). Thus, if the callback request another mutex M held by the another
+ * function, without releasing mutex_AU, then it will cause a deadlock when the
+ * another function, which holds the mutex M, request to use AudioUnit.
+ *
+ * The following figure illustrates the deadlock in bug 1337805:
+ * https://bugzilla.mozilla.org/show_bug.cgi?id=1337805
+ * (The detail analysis can be found on bug 1350511:
+ *  https://bugzilla.mozilla.org/show_bug.cgi?id=1350511)
+ *
+ *                   holds
+ *  data_callback <---------- mutext_AudioUnit(mutex_AU)
+ *      |                            ^
+ *      |                            |
+ *      | request                    | request
+ *      |                            |
+ *      v           holds            |
+ *  mutex_cubeb ------------> get_channel_layout
+ *
+ * In this example, the "audiounit_get_channel_layout" in f4edfb8:
+ * https://github.com/kinetiknz/cubeb/blob/f4edfb8eea920887713325e44773f3a2d959860c/src/cubeb_audiounit.cpp#L2725
+ * requests the mutex_AU to create an AudioUnit, when it holds a mutex for cubeb
+ * context. Meanwhile, the data callback who holds the mutex_AU requests the
+ * mutex for cubeb context. As a result, it causes a deadlock.
+ *
+ * The problem is solve by pull 236: https://github.com/kinetiknz/cubeb/pull/236
+ * We store the latest channel layout and return it when there is an active
+ * AudioUnit, otherwise, we will create an AudioUnit to get it.
+ *
+ * Although the problem is solved, to prevent it happens again, we add the test
+ * here in case someone without such knowledge misuses the AudioUnit in
+ * get_channel_layout. Moreover, it's a good way to record the known issues
+ * to warn other developers.
+ */
+
+#include "gtest/gtest.h"
+//#define ENABLE_NORMAL_LOG
+//#define ENABLE_VERBOSE_LOG
+#include "common.h"       // for layout_infos
+#include "cubeb/cubeb.h"  // for cubeb utils
+#include "cubeb_utils.h"  // for owned_critical_section, auto_lock
+#include <iostream>       // for fprintf
+#include <pthread.h>      // for pthread
+#include <signal.h>       // for signal
+#include <stdexcept>      // for std::logic_error
+#include <string>         // for std::string
+#include <unistd.h>       // for sleep, usleep
+#include <atomic>         // for std::atomic
+
+// The signal alias for calling our thread killer.
+#define CALL_THREAD_KILLER SIGUSR1
+
+// This indicator will become true when our pending task thread is killed by
+// ourselves.
+bool killed = false;
+
+// This indicator will become true when the assigned task is done.
+std::atomic<bool> task_done{ false };
+
+// Indicating the data callback is fired or not.
+bool called = false;
+
+// Toggle to true when running data callback. Before data callback gets
+// the mutex for cubeb context, it toggles back to false.
+// The task to get channel layout should be executed when this is true.
+std::atomic<bool> callbacking_before_getting_context{ false };
+
+owned_critical_section context_mutex;
+cubeb * context = nullptr;
+
+cubeb * get_cubeb_context_unlocked()
+{
+  if (context) {
+    return context;
+  }
+
+  int r = CUBEB_OK;
+  r = common_init(&context, "Cubeb deadlock test");
+  if (r != CUBEB_OK) {
+    context = nullptr;
+  }
+
+  return context;
+}
+
+cubeb * get_cubeb_context()
+{
+  auto_lock lock(context_mutex);
+  return get_cubeb_context_unlocked();
+}
+
+void state_cb_audio(cubeb_stream * /*stream*/, void * /*user*/, cubeb_state /*state*/)
+{
+}
+
+// Fired by coreaudio's rendering mechanism. It holds a mutex shared with the
+// current used AudioUnit.
+template<typename T>
+long data_cb(cubeb_stream * /*stream*/, void * /*user*/,
+             const void * /*inputbuffer*/, void * outputbuffer, long nframes)
+{
+  called = true;
+
+  uint64_t tid; // Current thread id.
+  pthread_threadid_np(NULL, &tid);
+  fprintf(stderr, "Audio output is on thread %llu\n", tid);
+
+  if (!task_done) {
+    callbacking_before_getting_context = true;
+    fprintf(stderr, "[%llu] time to switch thread\n", tid);
+    // Force to switch threads by sleeping 10 ms. Notice that anything over
+    // 10ms would create a glitch. It's intended here for test, so the delay
+    // is ok.
+    usleep(10000);
+    callbacking_before_getting_context = false;
+  }
+
+  fprintf(stderr, "[%llu] try getting backend id ...\n", tid);
+
+  // Try requesting mutex for context by get_cubeb_context()
+  // when holding a mutex for AudioUnit.
+  char const * backend_id = cubeb_get_backend_id(get_cubeb_context());
+  fprintf(stderr, "[%llu] callback on %s\n", tid, backend_id);
+
+  // Mute the output (or get deaf)
+  memset(outputbuffer, 0, nframes * 2 * sizeof(float));
+  return nframes;
+}
+
+// Called by wait_to_get_layout, which is run out of main thread.
+void get_preferred_channel_layout()
+{
+  auto_lock lock(context_mutex);
+  cubeb * context = get_cubeb_context_unlocked();
+  ASSERT_TRUE(!!context);
+
+  // We will cause a deadlock if cubeb_get_preferred_channel_layout requests
+  // mutex for AudioUnit when it holds mutex for context.
+  cubeb_channel_layout layout;
+  int r = cubeb_get_preferred_channel_layout(context, &layout);
+  ASSERT_EQ(r == CUBEB_OK, layout != CUBEB_LAYOUT_UNDEFINED);
+  fprintf(stderr, "layout is %s\n", layout_infos[layout].name);
+}
+
+void * wait_to_get_layout(void *)
+{
+  uint64_t tid; // Current thread id.
+  pthread_threadid_np(NULL, &tid);
+
+  while(!callbacking_before_getting_context) {
+    fprintf(stderr, "[%llu] waiting for data callback ...\n", tid);
+    usleep(1000); // Force to switch threads by sleeping 1 ms.
+  }
+
+  fprintf(stderr, "[%llu] try getting channel layout ...\n", tid);
+  get_preferred_channel_layout(); // Deadlock checkpoint.
+  task_done = true;
+
+  return NULL;
+}
+
+void * watchdog(void * s)
+{
+  uint64_t tid; // Current thread id.
+  pthread_threadid_np(NULL, &tid);
+
+  pthread_t subject = *((pthread_t *) s);
+  uint64_t stid; // task thread id.
+  pthread_threadid_np(subject, &stid);
+
+  unsigned int sec = 2;
+  fprintf(stderr, "[%llu] sleep %d seconds before checking task for thread %llu\n", tid, sec, stid);
+  sleep(sec); // Force to switch threads.
+
+  fprintf(stderr, "[%llu] check task for thread %llu now\n", tid, stid);
+  if (!task_done) {
+    fprintf(stderr, "[%llu] kill the task thread %llu\n", tid, stid);
+    pthread_kill(subject, CALL_THREAD_KILLER);
+    pthread_detach(subject);
+    // pthread_kill doesn't release the mutex held by the killed thread,
+    // so we need to unlock it manually.
+    context_mutex.unlock();
+  }
+  fprintf(stderr, "[%llu] the assigned task for thread %llu is %sdone\n", tid, stid, (task_done) ? "" : "not ");
+
+  return NULL;
+}
+
+void thread_killer(int signal)
+{
+  ASSERT_EQ(signal, CALL_THREAD_KILLER);
+  fprintf(stderr, "task thread is killed!\n");
+  killed = true;
+}
+
+TEST(cubeb, run_deadlock_test)
+{
+#if !defined(__APPLE__)
+  FAIL() << "Deadlock test is only for OSX now";
+#endif
+
+  cubeb * ctx = get_cubeb_context();
+  ASSERT_TRUE(!!ctx);
+
+  std::unique_ptr<cubeb, decltype(&cubeb_destroy)>
+    cleanup_cubeb_at_exit(ctx, cubeb_destroy);
+
+  cubeb_stream_params params;
+  params.format = CUBEB_SAMPLE_FLOAT32NE;
+  params.rate = 44100;
+  params.channels = 2;
+  params.layout = CUBEB_LAYOUT_STEREO;
+  params.prefs = CUBEB_STREAM_PREF_NONE;
+
+  cubeb_stream * stream = NULL;
+  int r = cubeb_stream_init(ctx, &stream, "test deadlock", NULL, NULL, NULL,
+                            &params, 512, &data_cb<float>, state_cb_audio, NULL);
+  ASSERT_EQ(r, CUBEB_OK);
+
+  std::unique_ptr<cubeb_stream, decltype(&cubeb_stream_destroy)>
+    cleanup_stream_at_exit(stream, cubeb_stream_destroy);
+
+  // Install signal handler.
+  signal(CALL_THREAD_KILLER, thread_killer);
+
+  pthread_t subject, detector;
+  pthread_create(&subject, NULL, wait_to_get_layout, NULL);
+  pthread_create(&detector, NULL, watchdog, (void *) &subject);
+
+  uint64_t stid, dtid;
+  pthread_threadid_np(subject, &stid);
+  pthread_threadid_np(detector, &dtid);
+  fprintf(stderr, "task thread %llu, monitor thread %llu are created\n", stid, dtid);
+
+  cubeb_stream_start(stream);
+
+  pthread_join(subject, NULL);
+  pthread_join(detector, NULL);
+
+  ASSERT_TRUE(called);
+
+  fprintf(stderr, "\n%sDeadlock detected!\n", (called && !task_done.load()) ? "" : "No ");
+
+  // Check the task is killed by ourselves if deadlock happends.
+  // Otherwise, thread_killer should not be triggered.
+  ASSERT_NE(task_done.load(), killed);
+
+  ASSERT_TRUE(task_done.load());
+
+  cubeb_stream_stop(stream);
+}
+
+#undef CALL_THREAD_KILLER