FenceTimeline: Fix a potential race condition
FenceTimeline::updateSignalTimes checks if mQueue is empty without
grabbing the lock. This can lead a situaltion that a threads calls
pop() on an empty queue.
Test: boot
Bug: 132735340
Change-Id: I3007bfc1161797cb4d853506bb354e820bc9105d
diff --git a/libs/ui/FenceTime.cpp b/libs/ui/FenceTime.cpp
index 340231d..bdfe04b 100644
--- a/libs/ui/FenceTime.cpp
+++ b/libs/ui/FenceTime.cpp
@@ -279,8 +279,8 @@
}
void FenceTimeline::updateSignalTimes() {
+ std::lock_guard<std::mutex> lock(mMutex);
while (!mQueue.empty()) {
- std::lock_guard<std::mutex> lock(mMutex);
std::shared_ptr<FenceTime> fence = mQueue.front().lock();
if (!fence) {
// The shared_ptr no longer exists and no one cares about the
diff --git a/libs/ui/include/ui/FenceTime.h b/libs/ui/include/ui/FenceTime.h
index a5a1fcb..ecba7f7 100644
--- a/libs/ui/include/ui/FenceTime.h
+++ b/libs/ui/include/ui/FenceTime.h
@@ -19,6 +19,7 @@
#include <ui/Fence.h>
#include <utils/Flattenable.h>
+#include <utils/Mutex.h>
#include <utils/Timers.h>
#include <atomic>
@@ -159,7 +160,7 @@
private:
mutable std::mutex mMutex;
- std::queue<std::weak_ptr<FenceTime>> mQueue;
+ std::queue<std::weak_ptr<FenceTime>> mQueue GUARDED_BY(mMutex);
};
// Used by test code to create or get FenceTimes for a given Fence.