Clean ComposerClient cache on hotplug

On subsequent hotplug connected event for a display
SurfaceFlinger destroys the previous framebuffers and
recreates them. When the new buffers are created
ComposerClient still holds a handle to the old buffers and
they are not destroyed. This way the new framebuffers
may get allocated on non continuous memory causing garbled
screens for the user.

Bug: 160112047
Bug: 169255692
Test: 1. limit cma ion memory to 32 MB
      2. flash device
      3. plug hdmi out and in
      4. verify that the display image is not garbled
Change-Id: Idf7cdf7a070ffc83ecec34ac24c8a7d696f68aa6
diff --git a/graphics/composer/2.1/utils/hal/include/composer-hal/2.1/ComposerClient.h b/graphics/composer/2.1/utils/hal/include/composer-hal/2.1/ComposerClient.h
index 47ead41..3d74af4 100644
--- a/graphics/composer/2.1/utils/hal/include/composer-hal/2.1/ComposerClient.h
+++ b/graphics/composer/2.1/utils/hal/include/composer-hal/2.1/ComposerClient.h
@@ -87,19 +87,28 @@
 
     class HalEventCallback : public Hal::EventCallback {
        public:
-        HalEventCallback(const sp<IComposerCallback> callback, ComposerResources* resources)
-            : mCallback(callback), mResources(resources) {}
+         HalEventCallback(Hal* hal, const sp<IComposerCallback> callback,
+                          ComposerResources* resources)
+             : mHal(hal), mCallback(callback), mResources(resources) {}
 
-        void onHotplug(Display display, IComposerCallback::Connection connected) {
-            if (connected == IComposerCallback::Connection::CONNECTED) {
-                mResources->addPhysicalDisplay(display);
-            } else if (connected == IComposerCallback::Connection::DISCONNECTED) {
-                mResources->removeDisplay(display);
-            }
+         void onHotplug(Display display, IComposerCallback::Connection connected) {
+             if (connected == IComposerCallback::Connection::CONNECTED) {
+                 if (mResources->hasDisplay(display)) {
+                     // This is a subsequent hotplug "connected" for a display. This signals a
+                     // display change and thus the framework may want to reallocate buffers. We
+                     // need to free all cached handles, since they are holding a strong reference
+                     // to the underlying buffers.
+                     cleanDisplayResources(display);
+                     mResources->removeDisplay(display);
+                 }
+                 mResources->addPhysicalDisplay(display);
+             } else if (connected == IComposerCallback::Connection::DISCONNECTED) {
+                 mResources->removeDisplay(display);
+             }
 
-            auto ret = mCallback->onHotplug(display, connected);
-            ALOGE_IF(!ret.isOk(), "failed to send onHotplug: %s", ret.description().c_str());
-        }
+             auto ret = mCallback->onHotplug(display, connected);
+             ALOGE_IF(!ret.isOk(), "failed to send onHotplug: %s", ret.description().c_str());
+         }
 
         void onRefresh(Display display) {
             mResources->setDisplayMustValidateState(display, true);
@@ -113,13 +122,64 @@
         }
 
        protected:
-        const sp<IComposerCallback> mCallback;
-        ComposerResources* const mResources;
+         Hal* const mHal;
+         const sp<IComposerCallback> mCallback;
+         ComposerResources* const mResources;
+
+         void cleanDisplayResources(Display display) {
+             size_t cacheSize;
+             Error err = mResources->getDisplayClientTargetCacheSize(display, &cacheSize);
+             if (err == Error::NONE) {
+                 for (int slot = 0; slot < cacheSize; slot++) {
+                     ComposerResources::ReplacedHandle replacedBuffer(/*isBuffer*/ true);
+                     // Replace the buffer slots with NULLs. Keep the old handle until it is
+                     // replaced in ComposerHal, otherwise we risk leaving a dangling pointer.
+                     const native_handle_t* clientTarget = nullptr;
+                     err = mResources->getDisplayClientTarget(display, slot, /*useCache*/ true,
+                                                              /*rawHandle*/ nullptr, &clientTarget,
+                                                              &replacedBuffer);
+                     if (err != Error::NONE) {
+                         continue;
+                     }
+                     const std::vector<hwc_rect_t> damage;
+                     err = mHal->setClientTarget(display, clientTarget, /*fence*/ -1, 0, damage);
+                     ALOGE_IF(err != Error::NONE,
+                              "Can't clean slot %d of the client target buffer"
+                              "cache for display %" PRIu64,
+                              slot, display);
+                 }
+             } else {
+                 ALOGE("Can't clean client target cache for display %" PRIu64, display);
+             }
+
+             err = mResources->getDisplayOutputBufferCacheSize(display, &cacheSize);
+             if (err == Error::NONE) {
+                 for (int slot = 0; slot < cacheSize; slot++) {
+                     // Replace the buffer slots with NULLs. Keep the old handle until it is
+                     // replaced in ComposerHal, otherwise we risk leaving a dangling pointer.
+                     ComposerResources::ReplacedHandle replacedBuffer(/*isBuffer*/ true);
+                     const native_handle_t* outputBuffer = nullptr;
+                     err = mResources->getDisplayOutputBuffer(display, slot, /*useCache*/ true,
+                                                              /*rawHandle*/ nullptr, &outputBuffer,
+                                                              &replacedBuffer);
+                     if (err != Error::NONE) {
+                         continue;
+                     }
+                     err = mHal->setOutputBuffer(display, outputBuffer, /*fence*/ -1);
+                     ALOGE_IF(err != Error::NONE,
+                              "Can't clean slot %d of the output buffer cache"
+                              "for display %" PRIu64,
+                              slot, display);
+                 }
+             } else {
+                 ALOGE("Can't clean output buffer cache for display %" PRIu64, display);
+             }
+         }
     };
 
     Return<void> registerCallback(const sp<IComposerCallback>& callback) override {
         // no locking as we require this function to be called only once
-        mHalEventCallback = std::make_unique<HalEventCallback>(callback, mResources.get());
+        mHalEventCallback = std::make_unique<HalEventCallback>(mHal, callback, mResources.get());
         mHal->registerEventCallback(mHalEventCallback.get());
         return Void();
     }
diff --git a/graphics/composer/2.1/utils/resources/ComposerResources.cpp b/graphics/composer/2.1/utils/resources/ComposerResources.cpp
index 21f6035..e52bf71 100644
--- a/graphics/composer/2.1/utils/resources/ComposerResources.cpp
+++ b/graphics/composer/2.1/utils/resources/ComposerResources.cpp
@@ -144,6 +144,10 @@
     }
 }
 
+size_t ComposerHandleCache::getCacheSize() const {
+    return mHandles.size();
+}
+
 bool ComposerHandleCache::initCache(HandleType type, uint32_t cacheSize) {
     // already initialized
     if (mHandleType != HandleType::INVALID) {
@@ -220,6 +224,14 @@
     return mClientTargetCache.initCache(ComposerHandleCache::HandleType::BUFFER, cacheSize);
 }
 
+size_t ComposerDisplayResource::getClientTargetCacheSize() const {
+    return mClientTargetCache.getCacheSize();
+}
+
+size_t ComposerDisplayResource::getOutputBufferCacheSize() const {
+    return mOutputBufferCache.getCacheSize();
+}
+
 bool ComposerDisplayResource::isVirtual() const {
     return mType == DisplayType::VIRTUAL;
 }
@@ -293,6 +305,10 @@
     mDisplayResources.clear();
 }
 
+bool ComposerResources::hasDisplay(Display display) {
+    return mDisplayResources.count(display) > 0;
+}
+
 Error ComposerResources::addPhysicalDisplay(Display display) {
     auto displayResource = createDisplayResource(ComposerDisplayResource::DisplayType::PHYSICAL, 0);
 
@@ -327,6 +343,26 @@
                                                                          : Error::BAD_PARAMETER;
 }
 
+Error ComposerResources::getDisplayClientTargetCacheSize(Display display, size_t* outCacheSize) {
+    std::lock_guard<std::mutex> lock(mDisplayResourcesMutex);
+    ComposerDisplayResource* displayResource = findDisplayResourceLocked(display);
+    if (!displayResource) {
+        return Error::BAD_DISPLAY;
+    }
+    *outCacheSize = displayResource->getClientTargetCacheSize();
+    return Error::NONE;
+}
+
+Error ComposerResources::getDisplayOutputBufferCacheSize(Display display, size_t* outCacheSize) {
+    std::lock_guard<std::mutex> lock(mDisplayResourcesMutex);
+    ComposerDisplayResource* displayResource = findDisplayResourceLocked(display);
+    if (!displayResource) {
+        return Error::BAD_DISPLAY;
+    }
+    *outCacheSize = displayResource->getOutputBufferCacheSize();
+    return Error::NONE;
+}
+
 Error ComposerResources::addLayer(Display display, Layer layer, uint32_t bufferCacheSize) {
     auto layerResource = createLayerResource(bufferCacheSize);
 
diff --git a/graphics/composer/2.1/utils/resources/include/composer-resources/2.1/ComposerResources.h b/graphics/composer/2.1/utils/resources/include/composer-resources/2.1/ComposerResources.h
index df5513e..de78a59 100644
--- a/graphics/composer/2.1/utils/resources/include/composer-resources/2.1/ComposerResources.h
+++ b/graphics/composer/2.1/utils/resources/include/composer-resources/2.1/ComposerResources.h
@@ -74,6 +74,7 @@
     ComposerHandleCache& operator=(const ComposerHandleCache&) = delete;
 
     bool initCache(HandleType type, uint32_t cacheSize);
+    size_t getCacheSize() const;
     Error lookupCache(uint32_t slot, const native_handle_t** outHandle);
     Error updateCache(uint32_t slot, const native_handle_t* handle,
                       const native_handle** outReplacedHandle);
@@ -120,7 +121,8 @@
                             uint32_t outputBufferCacheSize);
 
     bool initClientTargetCache(uint32_t cacheSize);
-
+    size_t getClientTargetCacheSize() const;
+    size_t getOutputBufferCacheSize() const;
     bool isVirtual() const;
 
     Error getClientTarget(uint32_t slot, bool fromCache, const native_handle_t* inHandle,
@@ -162,12 +164,15 @@
             std::function<void(Display display, bool isVirtual, const std::vector<Layer>& layers)>;
     void clear(RemoveDisplay removeDisplay);
 
+    bool hasDisplay(Display display);
     Error addPhysicalDisplay(Display display);
     Error addVirtualDisplay(Display display, uint32_t outputBufferCacheSize);
 
     Error removeDisplay(Display display);
 
     Error setDisplayClientTargetCacheSize(Display display, uint32_t clientTargetCacheSize);
+    Error getDisplayClientTargetCacheSize(Display display, size_t* outCacheSize);
+    Error getDisplayOutputBufferCacheSize(Display display, size_t* outCacheSize);
 
     Error addLayer(Display display, Layer layer, uint32_t bufferCacheSize);
     Error removeLayer(Display display, Layer layer);