Merge "Fix memory ordering issues; document IMemory peculiarities" (2347fca4) · Commits · e / os / platform_frameworks_native

libs/binder/IMemory.cpp

+30 −20

Original line number	Diff line number	Diff line
		@@ -16,6 +16,7 @@

		#define LOG_TAG "IMemory"

		#include <atomic>
		#include <stdint.h>
		#include <stdio.h>
		#include <stdlib.h>
		@@ -29,7 +30,6 @@
		#include <cutils/log.h>
		#include <utils/KeyedVector.h>
		#include <utils/threads.h>
		#include <utils/Atomic.h>
		#include <binder/Parcel.h>
		#include <utils/CallStack.h>

		@@ -56,12 +56,15 @@ private:
		struct heap_info_t {
		sp<IMemoryHeap> heap;
		int32_t count;
		// Note that this cannot be meaningfully copied.
		};

		void free_heap(const wp<IBinder>& binder);

		Mutex mHeapCacheLock;
		Mutex mHeapCacheLock; // Protects entire vector below.
		KeyedVector< wp<IBinder>, heap_info_t > mHeapCache;
		// We do not use the copy-on-write capabilities of KeyedVector.
		// TODO: Reimplemement based on standard C++ container?
		};

		static sp<HeapCache> gHeapCache = new HeapCache();
		@@ -105,7 +108,7 @@ private:
		void assertMapped() const;
		void assertReallyMapped() const;

		mutable volatile int32_t mHeapId;
		mutable std::atomic<int32_t> mHeapId;
		mutable void* mBase;
		mutable size_t mSize;
		mutable uint32_t mFlags;
		@@ -248,8 +251,9 @@ BpMemoryHeap::BpMemoryHeap(const sp<IBinder>& impl)
		}

		BpMemoryHeap::~BpMemoryHeap() {
		if (mHeapId != -1) {
		close(mHeapId);
		int32_t heapId = mHeapId.load(memory_order_relaxed);
		if (heapId != -1) {
		close(heapId);
		if (mRealHeap) {
		// by construction we're the last one
		if (mBase != MAP_FAILED) {
		@@ -257,7 +261,7 @@ BpMemoryHeap::~BpMemoryHeap() {

		if (VERBOSE) {
		ALOGD("UNMAPPING binder=%p, heap=%p, size=%zu, fd=%d",
		binder.get(), this, mSize, mHeapId);
		binder.get(), this, mSize, heapId);
		CallStack stack(LOG_TAG);
		}

		@@ -273,17 +277,21 @@ BpMemoryHeap::~BpMemoryHeap() {

		void BpMemoryHeap::assertMapped() const
		{
		if (mHeapId == -1) {
		int32_t heapId = mHeapId.load(memory_order_acquire);
		if (heapId == -1) {
		sp<IBinder> binder(IInterface::asBinder(const_cast<BpMemoryHeap*>(this)));
		sp<BpMemoryHeap> heap(static_cast<BpMemoryHeap*>(find_heap(binder).get()));
		heap->assertReallyMapped();
		if (heap->mBase != MAP_FAILED) {
		Mutex::Autolock _l(mLock);
		if (mHeapId == -1) {
		if (mHeapId.load(memory_order_relaxed) == -1) {
		mBase = heap->mBase;
		mSize = heap->mSize;
		mOffset = heap->mOffset;
		android_atomic_write( dup( heap->mHeapId ), &mHeapId );
		int fd = dup(heap->mHeapId.load(memory_order_relaxed));
		ALOGE_IF(fd==-1, "cannot dup fd=%d",
		heap->mHeapId.load(memory_order_relaxed));
		mHeapId.store(fd, memory_order_release);
		}
		} else {
		// something went wrong
		@@ -294,7 +302,8 @@ void BpMemoryHeap::assertMapped() const

		void BpMemoryHeap::assertReallyMapped() const
		{
		if (mHeapId == -1) {
		int32_t heapId = mHeapId.load(memory_order_acquire);
		if (heapId == -1) {

		// remote call without mLock held, worse case scenario, we end up
		// calling transact() from multiple threads, but that's not a problem,
		@@ -313,7 +322,7 @@ void BpMemoryHeap::assertReallyMapped() const
		parcel_fd, size, err, strerror(-err));

		Mutex::Autolock _l(mLock);
		if (mHeapId == -1) {
		if (mHeapId.load(memory_order_relaxed) == -1) {
		int fd = dup( parcel_fd );
		ALOGE_IF(fd==-1, "cannot dup fd=%d, size=%zd, err=%d (%s)",
		parcel_fd, size, err, strerror(errno));
		@@ -322,7 +331,6 @@ void BpMemoryHeap::assertReallyMapped() const
		if (!(flags & READ_ONLY)) {
		access \|= PROT_WRITE;
		}

		mRealHeap = true;
		mBase = mmap(0, size, access, MAP_SHARED, fd, offset);
		if (mBase == MAP_FAILED) {
		@@ -333,7 +341,7 @@ void BpMemoryHeap::assertReallyMapped() const
		mSize = size;
		mFlags = flags;
		mOffset = offset;
		android_atomic_write(fd, &mHeapId);
		mHeapId.store(fd, memory_order_release);
		}
		}
		}
		@@ -341,7 +349,8 @@ void BpMemoryHeap::assertReallyMapped() const

		int BpMemoryHeap::getHeapID() const {
		assertMapped();
		return mHeapId;
		// We either stored mHeapId ourselves, or loaded it with acquire semantics.
		return mHeapId.load(memory_order_relaxed);
		}

		void* BpMemoryHeap::getBase() const {
		@@ -418,9 +427,10 @@ sp<IMemoryHeap> HeapCache::find_heap(const sp<IBinder>& binder)
		"found binder=%p, heap=%p, size=%zu, fd=%d, count=%d",
		binder.get(), info.heap.get(),
		static_cast<BpMemoryHeap*>(info.heap.get())->mSize,
		static_cast<BpMemoryHeap*>(info.heap.get())->mHeapId,
		static_cast<BpMemoryHeap*>(info.heap.get())
		->mHeapId.load(memory_order_relaxed),
		info.count);
		android_atomic_inc(&info.count);
		++info.count;
		return info.heap;
		} else {
		heap_info_t info;
		@@ -445,13 +455,13 @@ void HeapCache::free_heap(const wp<IBinder>& binder)
		ssize_t i = mHeapCache.indexOfKey(binder);
		if (i>=0) {
		heap_info_t& info(mHeapCache.editValueAt(i));
		int32_t c = android_atomic_dec(&info.count);
		if (c == 1) {
		if (--info.count == 0) {
		ALOGD_IF(VERBOSE,
		"removing binder=%p, heap=%p, size=%zu, fd=%d, count=%d",
		binder.unsafe_get(), info.heap.get(),
		static_cast<BpMemoryHeap*>(info.heap.get())->mSize,
		static_cast<BpMemoryHeap*>(info.heap.get())->mHeapId,
		static_cast<BpMemoryHeap*>(info.heap.get())
		->mHeapId.load(memory_order_relaxed),
		info.count);
		rel = mHeapCache.valueAt(i).heap;
		mHeapCache.removeItemsAt(i);
		@@ -482,7 +492,7 @@ void HeapCache::dump_heaps()
		ALOGD("hey=%p, heap=%p, count=%d, (fd=%d, base=%p, size=%zu)",
		mHeapCache.keyAt(i).unsafe_get(),
		info.heap.get(), info.count,
		h->mHeapId, h->mBase, h->mSize);
		h->mHeapId.load(memory_order_relaxed), h->mBase, h->mSize);
		}
		}