Get window info debug data without holding the statelock
Avoids a deadlock with mStateLock when calling dumpsys
SurfaceFlinger. Deadlock happens because we make a blocking
call into the background thread holding the mStateLock. Background
thread may try to hold the mStateLock when destroying a layer handle
which can result in a deadlock.
Flag: EXEMPT bugfix
Test: presubmit, run dumpsys
Fixes: 347142017
Change-Id: Icda6d4ee0ead70a4d76a4f6fe766fdf40bae6d2c
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index d772780..5b40acf 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -6391,15 +6391,23 @@
return NO_ERROR;
}
- // Traversal of drawing state must happen on the main thread.
- // Otherwise, SortedVector may have shared ownership during concurrent
- // traversals, which can result in use-after-frees.
+ // Collect debug data from main thread
std::string compositionLayers;
mScheduler
->schedule([&]() FTL_FAKE_GUARD(mStateLock) FTL_FAKE_GUARD(kMainThreadContext) {
dumpVisibleFrontEnd(compositionLayers);
})
.get();
+ // get window info listener data without the state lock
+ auto windowInfosDebug = mWindowInfosListenerInvoker->getDebugInfo();
+ compositionLayers.append("Window Infos:\n");
+ StringAppendF(&compositionLayers, " max send vsync id: %" PRId64 "\n",
+ ftl::to_underlying(windowInfosDebug.maxSendDelayVsyncId));
+ StringAppendF(&compositionLayers, " max send delay (ns): %" PRId64 " ns\n",
+ windowInfosDebug.maxSendDelayDuration);
+ StringAppendF(&compositionLayers, " unsent messages: %zu\n",
+ windowInfosDebug.pendingMessageCount);
+ compositionLayers.append("\n");
dumpAll(args, compositionLayers, result);
write(fd, result.c_str(), result.size());
return NO_ERROR;
@@ -6982,15 +6990,6 @@
result.append(mTimeStats->miniDump());
result.append("\n");
-
- result.append("Window Infos:\n");
- auto windowInfosDebug = mWindowInfosListenerInvoker->getDebugInfo();
- StringAppendF(&result, " max send vsync id: %" PRId64 "\n",
- ftl::to_underlying(windowInfosDebug.maxSendDelayVsyncId));
- StringAppendF(&result, " max send delay (ns): %" PRId64 " ns\n",
- windowInfosDebug.maxSendDelayDuration);
- StringAppendF(&result, " unsent messages: %zu\n", windowInfosDebug.pendingMessageCount);
- result.append("\n");
}
mat4 SurfaceFlinger::calculateColorMatrix(float saturation) {