SF: protect mDisplayCapabilities with a lock
There is a rare race condition where mDisplayCapabilities can be
read while it is getting updated, which causes a crash.
Bug: 196059993
Test: SF unit tests
Change-Id: Iaca9f1b61cdc1a59639a93f62c1716acddf8186b
diff --git a/services/surfaceflinger/DisplayHardware/HWC2.cpp b/services/surfaceflinger/DisplayHardware/HWC2.cpp
index 27146ab..e21b0da 100644
--- a/services/surfaceflinger/DisplayHardware/HWC2.cpp
+++ b/services/surfaceflinger/DisplayHardware/HWC2.cpp
@@ -283,8 +283,21 @@
return Error::NONE;
}
+bool Display::hasCapability(hal::DisplayCapability capability) const {
+ std::scoped_lock lock(mDisplayCapabilitiesMutex);
+ if (mDisplayCapabilities) {
+ return mDisplayCapabilities->count(capability) > 0;
+ }
+
+ ALOGW("Can't query capability %d."
+ " Display Capabilities were not queried from HWC yet",
+ static_cast<int>(capability));
+
+ return false;
+}
+
Error Display::supportsDoze(bool* outSupport) const {
- *outSupport = mDisplayCapabilities.count(DisplayCapability::DOZE) > 0;
+ *outSupport = hasCapability(DisplayCapability::DOZE);
return Error::NONE;
}
@@ -447,17 +460,21 @@
auto error =
static_cast<Error>(mComposer.getDisplayCapabilities(mId, &tmpCapabilities));
if (error == Error::NONE) {
+ std::scoped_lock lock(mDisplayCapabilitiesMutex);
+ mDisplayCapabilities.emplace();
for (auto capability : tmpCapabilities) {
- mDisplayCapabilities.emplace(static_cast<DisplayCapability>(capability));
+ mDisplayCapabilities->emplace(static_cast<DisplayCapability>(capability));
}
} else if (error == Error::UNSUPPORTED) {
+ std::scoped_lock lock(mDisplayCapabilitiesMutex);
+ mDisplayCapabilities.emplace();
if (mCapabilities.count(Capability::SKIP_CLIENT_COLOR_TRANSFORM)) {
- mDisplayCapabilities.emplace(DisplayCapability::SKIP_CLIENT_COLOR_TRANSFORM);
+ mDisplayCapabilities->emplace(DisplayCapability::SKIP_CLIENT_COLOR_TRANSFORM);
}
bool dozeSupport = false;
error = static_cast<Error>(mComposer.getDozeSupport(mId, &dozeSupport));
if (error == Error::NONE && dozeSupport) {
- mDisplayCapabilities.emplace(DisplayCapability::DOZE);
+ mDisplayCapabilities->emplace(DisplayCapability::DOZE);
}
}
});
diff --git a/services/surfaceflinger/DisplayHardware/HWC2.h b/services/surfaceflinger/DisplayHardware/HWC2.h
index 871465d..a65efb2 100644
--- a/services/surfaceflinger/DisplayHardware/HWC2.h
+++ b/services/surfaceflinger/DisplayHardware/HWC2.h
@@ -17,6 +17,7 @@
#pragma once
#include <android-base/expected.h>
+#include <android-base/thread_annotations.h>
#include <gui/HdrMetadata.h>
#include <math/mat4.h>
#include <ui/HdrCapabilities.h>
@@ -79,7 +80,7 @@
virtual hal::HWDisplayId getId() const = 0;
virtual bool isConnected() const = 0;
virtual void setConnected(bool connected) = 0; // For use by Device only
- virtual const std::unordered_set<hal::DisplayCapability>& getCapabilities() const = 0;
+ virtual bool hasCapability(hal::DisplayCapability) const = 0;
virtual bool isVsyncPeriodSwitchSupported() const = 0;
virtual void onLayerDestroyed(hal::HWLayerId layerId) = 0;
@@ -175,7 +176,7 @@
hal::DisplayRequest* outDisplayRequests,
std::unordered_map<HWC2::Layer*, hal::LayerRequest>* outLayerRequests) override;
hal::Error getConnectionType(ui::DisplayConnectionType*) const override;
- hal::Error supportsDoze(bool* outSupport) const override;
+ hal::Error supportsDoze(bool* outSupport) const override EXCLUDES(mDisplayCapabilitiesMutex);
hal::Error getHdrCapabilities(android::HdrCapabilities* outCapabilities) const override;
hal::Error getDisplayedContentSamplingAttributes(hal::PixelFormat* outFormat,
hal::Dataspace* outDataspace,
@@ -214,9 +215,7 @@
hal::HWDisplayId getId() const override { return mId; }
bool isConnected() const override { return mIsConnected; }
void setConnected(bool connected) override; // For use by Device only
- const std::unordered_set<hal::DisplayCapability>& getCapabilities() const override {
- return mDisplayCapabilities;
- };
+ bool hasCapability(hal::DisplayCapability) const override EXCLUDES(mDisplayCapabilitiesMutex);
bool isVsyncPeriodSwitchSupported() const override;
void onLayerDestroyed(hal::HWLayerId layerId) override;
@@ -243,8 +242,10 @@
using Layers = std::unordered_map<hal::HWLayerId, std::weak_ptr<HWC2::impl::Layer>>;
Layers mLayers;
+ mutable std::mutex mDisplayCapabilitiesMutex;
std::once_flag mDisplayCapabilityQueryFlag;
- std::unordered_set<hal::DisplayCapability> mDisplayCapabilities;
+ std::optional<std::unordered_set<hal::DisplayCapability>> mDisplayCapabilities
+ GUARDED_BY(mDisplayCapabilitiesMutex);
};
} // namespace impl
diff --git a/services/surfaceflinger/DisplayHardware/HWComposer.cpp b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
index 256bca9..c63ba0e 100644
--- a/services/surfaceflinger/DisplayHardware/HWComposer.cpp
+++ b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
@@ -183,7 +183,7 @@
bool HWComposer::hasDisplayCapability(HalDisplayId displayId,
hal::DisplayCapability capability) const {
RETURN_IF_INVALID_DISPLAY(displayId, false);
- return mDisplayData.at(displayId).hwcDisplay->getCapabilities().count(capability) > 0;
+ return mDisplayData.at(displayId).hwcDisplay->hasCapability(capability);
}
std::optional<DisplayIdentificationInfo> HWComposer::onHotplug(hal::HWDisplayId hwcDisplayId,
diff --git a/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockHWC2.h b/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockHWC2.h
index c3919d9..fe1544e 100644
--- a/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockHWC2.h
+++ b/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockHWC2.h
@@ -30,8 +30,7 @@
MOCK_METHOD(hal::HWDisplayId, getId, (), (const, override));
MOCK_METHOD(bool, isConnected, (), (const, override));
MOCK_METHOD(void, setConnected, (bool), (override));
- MOCK_METHOD(const std::unordered_set<hal::DisplayCapability> &, getCapabilities, (),
- (const, override));
+ MOCK_METHOD(bool, hasCapability, (hal::DisplayCapability), (const, override));
MOCK_METHOD(bool, isVsyncPeriodSwitchSupported, (), (const, override));
MOCK_METHOD(void, onLayerDestroyed, (hal::HWLayerId), (override));