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Commit a06a9ff8 authored by TreeHugger Robot's avatar TreeHugger Robot Committed by Android (Google) Code Review
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Merge "Check atomics in shared memory are lock free"

parents 530e86d9 2ceb320e

libs/ui/BufferHubBuffer.cpp

+7 −0
Original line number Diff line number Diff line
@@ -169,6 +169,13 @@ int BufferHubBuffer::ImportGraphicBuffer() { 
    buffer_state_ = &metadata_header->buffer_state;

    fence_state_ = &metadata_header->fence_state;

    active_clients_bit_mask_ = &metadata_header->active_clients_bit_mask;

    // The C++ standard recommends (but does not require) that lock-free atomic operations are

    // also address-free, that is, suitable for communication between processes using shared

    // memory.

    LOG_ALWAYS_FATAL_IF(!std::atomic_is_lock_free(buffer_state_) ||

                                !std::atomic_is_lock_free(fence_state_) ||

                                !std::atomic_is_lock_free(active_clients_bit_mask_),

                        "Atomic variables in ashmen are not lock free.");



    // Import the buffer: We only need to hold on the native_handle_t here so that

    // GraphicBuffer instance can be created in future.

services/bufferhub/BufferNode.cpp

+8 −0
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ 


#include <bufferhub/BufferHubService.h>

#include <bufferhub/BufferNode.h>

#include <log/log.h>

#include <ui/GraphicBufferAllocator.h>



namespace android {
@@ -18,6 +19,13 @@ void BufferNode::InitializeMetadata() { 
    fence_state_ = new (&metadata_header->fence_state) std::atomic<uint32_t>(0);

    active_clients_bit_mask_ =

            new (&metadata_header->active_clients_bit_mask) std::atomic<uint32_t>(0);

    // The C++ standard recommends (but does not require) that lock-free atomic operations are

    // also address-free, that is, suitable for communication between processes using shared

    // memory.

    LOG_ALWAYS_FATAL_IF(!std::atomic_is_lock_free(buffer_state_) ||

                                !std::atomic_is_lock_free(fence_state_) ||

                                !std::atomic_is_lock_free(active_clients_bit_mask_),

                        "Atomic variables in ashmen are not lock free.");

}



// Allocates a new BufferNode.