Remove unnecessary copies of hidl_handle and its contents

Fix: 123582513
Test: BufferHub_test BufferHubServer_test VtsHalBufferHubV1_0TargetTest

Change-Id: I4d186d5ce34bc3b9714d94bfbcd6b0ce34294a6d

2 files changed, 31 insertions, 21 deletions

diff --git a/services/bufferhub/BufferHubService.cpp b/services/bufferhub/BufferHubService.cpp
index ae357cda8a..6b802fbf83 100644
--- a/services/bufferhub/BufferHubService.cpp
+++ b/services/bufferhub/BufferHubService.cpp
@@ -65,15 +65,20 @@ Return<void> BufferHubService::allocateBuffer(const HardwareBufferDescription& d
     std::lock_guard<std::mutex> lock(mClientSetMutex);
     mClientSet.emplace(client);
 
-    hidl_handle bufferInfo = buildBufferInfo(node->id(), node->AddNewActiveClientsBitToMask(),
-                                             node->user_metadata_size(), node->eventFd().get(),
-                                             node->metadata().ashmem_fd());
+    // Allocate memory for bufferInfo of type hidl_handle on the stack. See
+    // http://aosp/286282 for the usage of NATIVE_HANDLE_DECLARE_STORAGE.
+    NATIVE_HANDLE_DECLARE_STORAGE(bufferInfoStorage, BufferHubDefs::kBufferInfoNumFds,
+                                  BufferHubDefs::kBufferInfoNumInts);
+    hidl_handle bufferInfo =
+            buildBufferInfo(bufferInfoStorage, node->id(), node->AddNewActiveClientsBitToMask(),
+                            node->user_metadata_size(), node->metadata().ashmem_fd(),
+                            node->eventFd().get());
     BufferTraits bufferTraits = {/*bufferDesc=*/description,
                                  /*bufferHandle=*/hidl_handle(node->buffer_handle()),
-                                 /*bufferInfo=*/bufferInfo};
+                                 /*bufferInfo=*/std::move(bufferInfo)};
 
     _hidl_cb(/*status=*/BufferHubStatus::NO_ERROR, /*bufferClient=*/client,
-             /*bufferTraits=*/bufferTraits);
+             /*bufferTraits=*/std::move(bufferTraits));
     return Void();
 }
 
@@ -154,15 +159,19 @@ Return<void> BufferHubService::importBuffer(const hidl_handle& tokenHandle,
     HardwareBufferDescription bufferDesc;
     memcpy(&bufferDesc, &node->buffer_desc(), sizeof(HardwareBufferDescription));
 
-    hidl_handle bufferInfo =
-            buildBufferInfo(node->id(), clientStateMask, node->user_metadata_size(),
-                            node->eventFd().get(), node->metadata().ashmem_fd());
+    // Allocate memory for bufferInfo of type hidl_handle on the stack. See
+    // http://aosp/286282 for the usage of NATIVE_HANDLE_DECLARE_STORAGE.
+    NATIVE_HANDLE_DECLARE_STORAGE(bufferInfoStorage, BufferHubDefs::kBufferInfoNumFds,
+                                  BufferHubDefs::kBufferInfoNumInts);
+    hidl_handle bufferInfo = buildBufferInfo(bufferInfoStorage, node->id(), clientStateMask,
+                                             node->user_metadata_size(),
+                                             node->metadata().ashmem_fd(), node->eventFd().get());
     BufferTraits bufferTraits = {/*bufferDesc=*/bufferDesc,
                                  /*bufferHandle=*/hidl_handle(node->buffer_handle()),
-                                 /*bufferInfo=*/bufferInfo};
+                                 /*bufferInfo=*/std::move(bufferInfo)};
 
     _hidl_cb(/*status=*/BufferHubStatus::NO_ERROR, /*bufferClient=*/client,
-             /*bufferTraits=*/bufferTraits);
+             /*bufferTraits=*/std::move(bufferTraits));
     return Void();
 }
 
@@ -344,14 +353,15 @@ void BufferHubService::onClientClosed(const BufferClient* client) {
 
 // Implementation of this function should be consistent with the definition of bufferInfo handle in
 // ui/BufferHubDefs.h.
-hidl_handle BufferHubService::buildBufferInfo(int bufferId, uint32_t clientBitMask,
-                                              uint32_t userMetadataSize, const int eventFd,
-                                              const int metadataFd) {
-    native_handle_t* infoHandle = native_handle_create(BufferHubDefs::kBufferInfoNumFds,
-                                                       BufferHubDefs::kBufferInfoNumInts);
-
-    infoHandle->data[0] = dup(metadataFd);
-    infoHandle->data[1] = dup(eventFd);
+hidl_handle BufferHubService::buildBufferInfo(char* bufferInfoStorage, int bufferId,
+                                              uint32_t clientBitMask, uint32_t userMetadataSize,
+                                              int metadataFd, int eventFd) {
+    native_handle_t* infoHandle =
+            native_handle_init(bufferInfoStorage, BufferHubDefs::kBufferInfoNumFds,
+                               BufferHubDefs::kBufferInfoNumInts);
+
+    infoHandle->data[0] = metadataFd;
+    infoHandle->data[1] = eventFd;
     infoHandle->data[2] = bufferId;
     // Use memcpy to convert to int without missing digit.
     // TOOD(b/121345852): use bit_cast to unpack bufferInfo when C++20 becomes available.
@@ -359,7 +369,7 @@ hidl_handle BufferHubService::buildBufferInfo(int bufferId, uint32_t clientBitMa
     memcpy(&infoHandle->data[4], &userMetadataSize, sizeof(userMetadataSize));
 
     hidl_handle bufferInfo;
-    bufferInfo.setTo(infoHandle, /*shouldOwn=*/true);
+    bufferInfo.setTo(infoHandle, /*shouldOwn=*/false);
 
     return bufferInfo;
 }
diff --git a/services/bufferhub/include/bufferhub/BufferHubService.h b/services/bufferhub/include/bufferhub/BufferHubService.h
index 9015e05e46..edad20b194 100644
--- a/services/bufferhub/include/bufferhub/BufferHubService.h
+++ b/services/bufferhub/include/bufferhub/BufferHubService.h
@@ -58,8 +58,8 @@ public:
 
 private:
     // Helper function to build BufferTraits.bufferInfo handle
-    hidl_handle buildBufferInfo(int bufferId, uint32_t clientBitMask, uint32_t userMetadataSize,
-                                const int eventFd, const int metadataFd);
+    hidl_handle buildBufferInfo(char* bufferInfoStorage, int bufferId, uint32_t clientBitMask,
+                                uint32_t userMetadataSize, int metadataFd, int eventFd);
 
     // Helper function to remove all the token belongs to a specific client.
     void removeTokenByClient(const BufferClient* client);