* Copyright (c) 1998-2000 Apple Computer, Inc. All rights reserved.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
- *
+ *
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* unlawful or unlicensed copies of an Apple operating system, or to
* circumvent, violate, or enable the circumvention or violation of, any
* terms of an Apple operating system software license agreement.
- *
+ *
* Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this file.
- *
+ *
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
- *
+ *
* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
*/
IOSharedDataQueue *IOSharedDataQueue::withCapacity(UInt32 size)
{
- IOSharedDataQueue *dataQueue = new IOSharedDataQueue;
+ IOSharedDataQueue *dataQueue = new IOSharedDataQueue;
- if (dataQueue) {
- if (!dataQueue->initWithCapacity(size)) {
- dataQueue->release();
- dataQueue = 0;
- }
- }
+ if (dataQueue) {
+ if (!dataQueue->initWithCapacity(size)) {
+ dataQueue->release();
+ dataQueue = NULL;
+ }
+ }
- return dataQueue;
+ return dataQueue;
}
-IOSharedDataQueue *IOSharedDataQueue::withEntries(UInt32 numEntries, UInt32 entrySize)
+IOSharedDataQueue *
+IOSharedDataQueue::withEntries(UInt32 numEntries, UInt32 entrySize)
{
- IOSharedDataQueue *dataQueue = new IOSharedDataQueue;
+ IOSharedDataQueue *dataQueue = new IOSharedDataQueue;
- if (dataQueue) {
- if (!dataQueue->initWithEntries(numEntries, entrySize)) {
- dataQueue->release();
- dataQueue = 0;
- }
- }
+ if (dataQueue) {
+ if (!dataQueue->initWithEntries(numEntries, entrySize)) {
+ dataQueue->release();
+ dataQueue = NULL;
+ }
+ }
- return dataQueue;
+ return dataQueue;
}
-Boolean IOSharedDataQueue::initWithCapacity(UInt32 size)
+Boolean
+IOSharedDataQueue::initWithCapacity(UInt32 size)
{
- IODataQueueAppendix * appendix;
- vm_size_t allocSize;
-
- if (!super::init()) {
- return false;
- }
-
- _reserved = (ExpansionData *)IOMalloc(sizeof(struct ExpansionData));
- if (!_reserved) {
- return false;
- }
-
- if (size > UINT32_MAX - DATA_QUEUE_MEMORY_HEADER_SIZE - DATA_QUEUE_MEMORY_APPENDIX_SIZE) {
- return false;
- }
-
- allocSize = round_page(size + DATA_QUEUE_MEMORY_HEADER_SIZE + DATA_QUEUE_MEMORY_APPENDIX_SIZE);
-
- if (allocSize < size) {
- return false;
- }
-
- dataQueue = (IODataQueueMemory *)IOMallocAligned(allocSize, PAGE_SIZE);
- if (dataQueue == 0) {
- return false;
- }
- bzero(dataQueue, allocSize);
-
- dataQueue->queueSize = size;
+ IODataQueueAppendix * appendix;
+ vm_size_t allocSize;
+
+ if (!super::init()) {
+ return false;
+ }
+
+ _reserved = (ExpansionData *)IOMalloc(sizeof(struct ExpansionData));
+ if (!_reserved) {
+ return false;
+ }
+
+ if (size > UINT32_MAX - DATA_QUEUE_MEMORY_HEADER_SIZE - DATA_QUEUE_MEMORY_APPENDIX_SIZE) {
+ return false;
+ }
+
+ allocSize = round_page(size + DATA_QUEUE_MEMORY_HEADER_SIZE + DATA_QUEUE_MEMORY_APPENDIX_SIZE);
+
+ if (allocSize < size) {
+ return false;
+ }
+
+ dataQueue = (IODataQueueMemory *)IOMallocAligned(allocSize, PAGE_SIZE);
+ if (dataQueue == NULL) {
+ return false;
+ }
+ bzero(dataQueue, allocSize);
+
+ dataQueue->queueSize = size;
// dataQueue->head = 0;
// dataQueue->tail = 0;
- if (!setQueueSize(size)) {
- return false;
- }
-
- appendix = (IODataQueueAppendix *)((UInt8 *)dataQueue + size + DATA_QUEUE_MEMORY_HEADER_SIZE);
- appendix->version = 0;
+ if (!setQueueSize(size)) {
+ return false;
+ }
+
+ appendix = (IODataQueueAppendix *)((UInt8 *)dataQueue + size + DATA_QUEUE_MEMORY_HEADER_SIZE);
+ appendix->version = 0;
- if (!notifyMsg) {
- notifyMsg = IOMalloc(sizeof(mach_msg_header_t));
- if (!notifyMsg)
- return false;
- }
- bzero(notifyMsg, sizeof(mach_msg_header_t));
+ if (!notifyMsg) {
+ notifyMsg = IOMalloc(sizeof(mach_msg_header_t));
+ if (!notifyMsg) {
+ return false;
+ }
+ }
+ bzero(notifyMsg, sizeof(mach_msg_header_t));
- setNotificationPort(MACH_PORT_NULL);
+ setNotificationPort(MACH_PORT_NULL);
- return true;
+ return true;
}
-void IOSharedDataQueue::free()
+void
+IOSharedDataQueue::free()
{
- if (dataQueue) {
- IOFreeAligned(dataQueue, round_page(getQueueSize() + DATA_QUEUE_MEMORY_HEADER_SIZE + DATA_QUEUE_MEMORY_APPENDIX_SIZE));
- dataQueue = NULL;
- if (notifyMsg) {
- IOFree(notifyMsg, sizeof(mach_msg_header_t));
- notifyMsg = NULL;
- }
- }
-
- if (_reserved) {
- IOFree (_reserved, sizeof(struct ExpansionData));
- _reserved = NULL;
- }
-
- super::free();
+ if (dataQueue) {
+ IOFreeAligned(dataQueue, round_page(getQueueSize() + DATA_QUEUE_MEMORY_HEADER_SIZE + DATA_QUEUE_MEMORY_APPENDIX_SIZE));
+ dataQueue = NULL;
+ if (notifyMsg) {
+ IOFree(notifyMsg, sizeof(mach_msg_header_t));
+ notifyMsg = NULL;
+ }
+ }
+
+ if (_reserved) {
+ IOFree(_reserved, sizeof(struct ExpansionData));
+ _reserved = NULL;
+ }
+
+ super::free();
}
-IOMemoryDescriptor *IOSharedDataQueue::getMemoryDescriptor()
+IOMemoryDescriptor *
+IOSharedDataQueue::getMemoryDescriptor()
{
- IOMemoryDescriptor *descriptor = 0;
+ IOMemoryDescriptor *descriptor = NULL;
- if (dataQueue != 0) {
- descriptor = IOMemoryDescriptor::withAddress(dataQueue, getQueueSize() + DATA_QUEUE_MEMORY_HEADER_SIZE + DATA_QUEUE_MEMORY_APPENDIX_SIZE, kIODirectionOutIn);
- }
+ if (dataQueue != NULL) {
+ descriptor = IOMemoryDescriptor::withAddress(dataQueue, getQueueSize() + DATA_QUEUE_MEMORY_HEADER_SIZE + DATA_QUEUE_MEMORY_APPENDIX_SIZE, kIODirectionOutIn);
+ }
- return descriptor;
+ return descriptor;
}
-IODataQueueEntry * IOSharedDataQueue::peek()
+IODataQueueEntry *
+IOSharedDataQueue::peek()
{
- IODataQueueEntry *entry = 0;
- UInt32 headOffset;
- UInt32 tailOffset;
-
- if (!dataQueue) {
- return NULL;
- }
-
- // Read head and tail with acquire barrier
- headOffset = __c11_atomic_load((_Atomic UInt32 *)&dataQueue->head, __ATOMIC_RELAXED);
- tailOffset = __c11_atomic_load((_Atomic UInt32 *)&dataQueue->tail, __ATOMIC_ACQUIRE);
-
- if (headOffset != tailOffset) {
- IODataQueueEntry * head = 0;
- UInt32 headSize = 0;
- UInt32 headOffset = dataQueue->head;
- UInt32 queueSize = getQueueSize();
-
- if (headOffset >= queueSize) {
- return NULL;
- }
-
- head = (IODataQueueEntry *)((char *)dataQueue->queue + headOffset);
- headSize = head->size;
-
- // Check if there's enough room before the end of the queue for a header.
- // If there is room, check if there's enough room to hold the header and
- // the data.
-
- if ((headOffset > UINT32_MAX - DATA_QUEUE_ENTRY_HEADER_SIZE) ||
- (headOffset + DATA_QUEUE_ENTRY_HEADER_SIZE > queueSize) ||
- (headOffset + DATA_QUEUE_ENTRY_HEADER_SIZE > UINT32_MAX - headSize) ||
- (headOffset + headSize + DATA_QUEUE_ENTRY_HEADER_SIZE > queueSize)) {
- // No room for the header or the data, wrap to the beginning of the queue.
- // Note: wrapping even with the UINT32_MAX checks, as we have to support
- // queueSize of UINT32_MAX
- entry = dataQueue->queue;
- } else {
- entry = head;
- }
- }
-
- return entry;
+ IODataQueueEntry *entry = NULL;
+ UInt32 headOffset;
+ UInt32 tailOffset;
+
+ if (!dataQueue) {
+ return NULL;
+ }
+
+ // Read head and tail with acquire barrier
+ // See rdar://problem/40780584 for an explanation of relaxed/acquire barriers
+ headOffset = __c11_atomic_load((_Atomic UInt32 *)&dataQueue->head, __ATOMIC_RELAXED);
+ tailOffset = __c11_atomic_load((_Atomic UInt32 *)&dataQueue->tail, __ATOMIC_ACQUIRE);
+
+ if (headOffset != tailOffset) {
+ volatile IODataQueueEntry * head = NULL;
+ UInt32 headSize = 0;
+ UInt32 headOffset = dataQueue->head;
+ UInt32 queueSize = getQueueSize();
+
+ if (headOffset >= queueSize) {
+ return NULL;
+ }
+
+ head = (IODataQueueEntry *)((char *)dataQueue->queue + headOffset);
+ headSize = head->size;
+
+ // Check if there's enough room before the end of the queue for a header.
+ // If there is room, check if there's enough room to hold the header and
+ // the data.
+
+ if ((headOffset > UINT32_MAX - DATA_QUEUE_ENTRY_HEADER_SIZE) ||
+ (headOffset + DATA_QUEUE_ENTRY_HEADER_SIZE > queueSize) ||
+ (headOffset + DATA_QUEUE_ENTRY_HEADER_SIZE > UINT32_MAX - headSize) ||
+ (headOffset + headSize + DATA_QUEUE_ENTRY_HEADER_SIZE > queueSize)) {
+ // No room for the header or the data, wrap to the beginning of the queue.
+ // Note: wrapping even with the UINT32_MAX checks, as we have to support
+ // queueSize of UINT32_MAX
+ entry = dataQueue->queue;
+ } else {
+ entry = (IODataQueueEntry *)head;
+ }
+ }
+
+ return entry;
}
-Boolean IOSharedDataQueue::enqueue(void * data, UInt32 dataSize)
+Boolean
+IOSharedDataQueue::enqueue(void * data, UInt32 dataSize)
{
- UInt32 head;
- UInt32 tail;
- UInt32 newTail;
- const UInt32 entrySize = dataSize + DATA_QUEUE_ENTRY_HEADER_SIZE;
- IODataQueueEntry * entry;
-
- // Force a single read of head and tail
- head = __c11_atomic_load((_Atomic UInt32 *)&dataQueue->head, __ATOMIC_RELAXED);
- tail = __c11_atomic_load((_Atomic UInt32 *)&dataQueue->tail, __ATOMIC_RELAXED);
-
- // Check for overflow of entrySize
- if (dataSize > UINT32_MAX - DATA_QUEUE_ENTRY_HEADER_SIZE) {
- return false;
- }
- // Check for underflow of (getQueueSize() - tail)
- if (getQueueSize() < tail || getQueueSize() < head) {
- return false;
- }
-
- if ( tail >= head )
- {
- // Is there enough room at the end for the entry?
- if ((entrySize <= UINT32_MAX - tail) &&
- ((tail + entrySize) <= getQueueSize()) )
- {
- entry = (IODataQueueEntry *)((UInt8 *)dataQueue->queue + tail);
-
- entry->size = dataSize;
- memcpy(&entry->data, data, dataSize);
-
- // The tail can be out of bound when the size of the new entry
- // exactly matches the available space at the end of the queue.
- // The tail can range from 0 to dataQueue->queueSize inclusive.
-
- newTail = tail + entrySize;
- }
- else if ( head > entrySize ) // Is there enough room at the beginning?
- {
- // Wrap around to the beginning, but do not allow the tail to catch
- // up to the head.
-
- dataQueue->queue->size = dataSize;
-
- // We need to make sure that there is enough room to set the size before
- // doing this. The user client checks for this and will look for the size
- // at the beginning if there isn't room for it at the end.
-
- if ( ( getQueueSize() - tail ) >= DATA_QUEUE_ENTRY_HEADER_SIZE )
- {
- ((IODataQueueEntry *)((UInt8 *)dataQueue->queue + tail))->size = dataSize;
- }
-
- memcpy(&dataQueue->queue->data, data, dataSize);
- newTail = entrySize;
- }
- else
- {
- return false; // queue is full
- }
- }
- else
- {
- // Do not allow the tail to catch up to the head when the queue is full.
- // That's why the comparison uses a '>' rather than '>='.
-
- if ( (head - tail) > entrySize )
- {
- entry = (IODataQueueEntry *)((UInt8 *)dataQueue->queue + tail);
-
- entry->size = dataSize;
- memcpy(&entry->data, data, dataSize);
- newTail = tail + entrySize;
- }
- else
- {
- return false; // queue is full
- }
- }
-
- // Update tail with release barrier
- __c11_atomic_store((_Atomic UInt32 *)&dataQueue->tail, newTail, __ATOMIC_RELEASE);
-
- // Send notification (via mach message) that data is available.
-
- if ( ( tail == head ) /* queue was empty prior to enqueue() */
- || ( tail == __c11_atomic_load((_Atomic UInt32 *)&dataQueue->head, __ATOMIC_RELAXED) ) ) /* queue was emptied during enqueue() */
- {
- sendDataAvailableNotification();
- }
-
- return true;
+ UInt32 head;
+ UInt32 tail;
+ UInt32 newTail;
+ const UInt32 entrySize = dataSize + DATA_QUEUE_ENTRY_HEADER_SIZE;
+ IODataQueueEntry * entry;
+
+ // Force a single read of head and tail
+ // See rdar://problem/40780584 for an explanation of relaxed/acquire barriers
+ tail = __c11_atomic_load((_Atomic UInt32 *)&dataQueue->tail, __ATOMIC_RELAXED);
+ head = __c11_atomic_load((_Atomic UInt32 *)&dataQueue->head, __ATOMIC_ACQUIRE);
+
+ // Check for overflow of entrySize
+ if (dataSize > UINT32_MAX - DATA_QUEUE_ENTRY_HEADER_SIZE) {
+ return false;
+ }
+ // Check for underflow of (getQueueSize() - tail)
+ if (getQueueSize() < tail || getQueueSize() < head) {
+ return false;
+ }
+
+ if (tail >= head) {
+ // Is there enough room at the end for the entry?
+ if ((entrySize <= UINT32_MAX - tail) &&
+ ((tail + entrySize) <= getQueueSize())) {
+ entry = (IODataQueueEntry *)((UInt8 *)dataQueue->queue + tail);
+
+ entry->size = dataSize;
+ __nochk_memcpy(&entry->data, data, dataSize);
+
+ // The tail can be out of bound when the size of the new entry
+ // exactly matches the available space at the end of the queue.
+ // The tail can range from 0 to dataQueue->queueSize inclusive.
+
+ newTail = tail + entrySize;
+ } else if (head > entrySize) { // Is there enough room at the beginning?
+ // Wrap around to the beginning, but do not allow the tail to catch
+ // up to the head.
+
+ dataQueue->queue->size = dataSize;
+
+ // We need to make sure that there is enough room to set the size before
+ // doing this. The user client checks for this and will look for the size
+ // at the beginning if there isn't room for it at the end.
+
+ if ((getQueueSize() - tail) >= DATA_QUEUE_ENTRY_HEADER_SIZE) {
+ ((IODataQueueEntry *)((UInt8 *)dataQueue->queue + tail))->size = dataSize;
+ }
+
+ __nochk_memcpy(&dataQueue->queue->data, data, dataSize);
+ newTail = entrySize;
+ } else {
+ return false; // queue is full
+ }
+ } else {
+ // Do not allow the tail to catch up to the head when the queue is full.
+ // That's why the comparison uses a '>' rather than '>='.
+
+ if ((head - tail) > entrySize) {
+ entry = (IODataQueueEntry *)((UInt8 *)dataQueue->queue + tail);
+
+ entry->size = dataSize;
+ __nochk_memcpy(&entry->data, data, dataSize);
+ newTail = tail + entrySize;
+ } else {
+ return false; // queue is full
+ }
+ }
+
+ // Publish the data we just enqueued
+ __c11_atomic_store((_Atomic UInt32 *)&dataQueue->tail, newTail, __ATOMIC_RELEASE);
+
+ if (tail != head) {
+ //
+ // The memory barrier below paris with the one in ::dequeue
+ // so that either our store to the tail cannot be missed by
+ // the next dequeue attempt, or we will observe the dequeuer
+ // making the queue empty.
+ //
+ // Of course, if we already think the queue is empty,
+ // there's no point paying this extra cost.
+ //
+ __c11_atomic_thread_fence(__ATOMIC_SEQ_CST);
+ head = __c11_atomic_load((_Atomic UInt32 *)&dataQueue->head, __ATOMIC_RELAXED);
+ }
+
+ if (tail == head) {
+ // Send notification (via mach message) that data is now available.
+ sendDataAvailableNotification();
+ }
+ return true;
}
-Boolean IOSharedDataQueue::dequeue(void *data, UInt32 *dataSize)
+Boolean
+IOSharedDataQueue::dequeue(void *data, UInt32 *dataSize)
{
- Boolean retVal = TRUE;
- IODataQueueEntry * entry = 0;
- UInt32 entrySize = 0;
- UInt32 headOffset = 0;
- UInt32 tailOffset = 0;
- UInt32 newHeadOffset = 0;
-
- if (!dataQueue) {
- return false;
- }
-
- // Read head and tail with acquire barrier
- tailOffset = __c11_atomic_load((_Atomic UInt32 *)&dataQueue->tail, __ATOMIC_RELAXED);
- headOffset = __c11_atomic_load((_Atomic UInt32 *)&dataQueue->head, __ATOMIC_ACQUIRE);
-
- if (headOffset != tailOffset) {
- IODataQueueEntry * head = 0;
- UInt32 headSize = 0;
- UInt32 queueSize = getQueueSize();
-
- if (headOffset > queueSize) {
- return false;
- }
-
- head = (IODataQueueEntry *)((char *)dataQueue->queue + headOffset);
- headSize = head->size;
-
- // we wrapped around to beginning, so read from there
- // either there was not even room for the header
- if ((headOffset > UINT32_MAX - DATA_QUEUE_ENTRY_HEADER_SIZE) ||
- (headOffset + DATA_QUEUE_ENTRY_HEADER_SIZE > queueSize) ||
- // or there was room for the header, but not for the data
- (headOffset + DATA_QUEUE_ENTRY_HEADER_SIZE > UINT32_MAX - headSize) ||
- (headOffset + headSize + DATA_QUEUE_ENTRY_HEADER_SIZE > queueSize)) {
- // Note: we have to wrap to the beginning even with the UINT32_MAX checks
- // because we have to support a queueSize of UINT32_MAX.
- entry = dataQueue->queue;
- entrySize = entry->size;
- if ((entrySize > UINT32_MAX - DATA_QUEUE_ENTRY_HEADER_SIZE) ||
- (entrySize + DATA_QUEUE_ENTRY_HEADER_SIZE > queueSize)) {
- return false;
- }
- newHeadOffset = entrySize + DATA_QUEUE_ENTRY_HEADER_SIZE;
- // else it is at the end
- } else {
- entry = head;
- entrySize = entry->size;
- if ((entrySize > UINT32_MAX - DATA_QUEUE_ENTRY_HEADER_SIZE) ||
- (entrySize + DATA_QUEUE_ENTRY_HEADER_SIZE > UINT32_MAX - headOffset) ||
- (entrySize + DATA_QUEUE_ENTRY_HEADER_SIZE + headOffset > queueSize)) {
- return false;
- }
- newHeadOffset = headOffset + entrySize + DATA_QUEUE_ENTRY_HEADER_SIZE;
- }
- }
-
- if (entry) {
- if (data) {
- if (dataSize) {
- if (entrySize <= *dataSize) {
- memcpy(data, &(entry->data), entrySize);
- __c11_atomic_store((_Atomic UInt32 *)&dataQueue->head, newHeadOffset, __ATOMIC_RELEASE);
- } else {
- retVal = FALSE;
- }
- } else {
- retVal = FALSE;
- }
- } else {
- __c11_atomic_store((_Atomic UInt32 *)&dataQueue->head, newHeadOffset, __ATOMIC_RELEASE);
- }
-
- if (dataSize) {
- *dataSize = entrySize;
- }
- } else {
- retVal = FALSE;
- }
-
- return retVal;
+ Boolean retVal = TRUE;
+ volatile IODataQueueEntry * entry = NULL;
+ UInt32 entrySize = 0;
+ UInt32 headOffset = 0;
+ UInt32 tailOffset = 0;
+ UInt32 newHeadOffset = 0;
+
+ if (!dataQueue || (data && !dataSize)) {
+ return false;
+ }
+
+ // Read head and tail with acquire barrier
+ // See rdar://problem/40780584 for an explanation of relaxed/acquire barriers
+ headOffset = __c11_atomic_load((_Atomic UInt32 *)&dataQueue->head, __ATOMIC_RELAXED);
+ tailOffset = __c11_atomic_load((_Atomic UInt32 *)&dataQueue->tail, __ATOMIC_ACQUIRE);
+
+ if (headOffset != tailOffset) {
+ volatile IODataQueueEntry * head = NULL;
+ UInt32 headSize = 0;
+ UInt32 queueSize = getQueueSize();
+
+ if (headOffset > queueSize) {
+ return false;
+ }
+
+ head = (IODataQueueEntry *)((char *)dataQueue->queue + headOffset);
+ headSize = head->size;
+
+ // we wrapped around to beginning, so read from there
+ // either there was not even room for the header
+ if ((headOffset > UINT32_MAX - DATA_QUEUE_ENTRY_HEADER_SIZE) ||
+ (headOffset + DATA_QUEUE_ENTRY_HEADER_SIZE > queueSize) ||
+ // or there was room for the header, but not for the data
+ (headOffset + DATA_QUEUE_ENTRY_HEADER_SIZE > UINT32_MAX - headSize) ||
+ (headOffset + headSize + DATA_QUEUE_ENTRY_HEADER_SIZE > queueSize)) {
+ // Note: we have to wrap to the beginning even with the UINT32_MAX checks
+ // because we have to support a queueSize of UINT32_MAX.
+ entry = dataQueue->queue;
+ entrySize = entry->size;
+ if ((entrySize > UINT32_MAX - DATA_QUEUE_ENTRY_HEADER_SIZE) ||
+ (entrySize + DATA_QUEUE_ENTRY_HEADER_SIZE > queueSize)) {
+ return false;
+ }
+ newHeadOffset = entrySize + DATA_QUEUE_ENTRY_HEADER_SIZE;
+ // else it is at the end
+ } else {
+ entry = head;
+ entrySize = entry->size;
+ if ((entrySize > UINT32_MAX - DATA_QUEUE_ENTRY_HEADER_SIZE) ||
+ (entrySize + DATA_QUEUE_ENTRY_HEADER_SIZE > UINT32_MAX - headOffset) ||
+ (entrySize + DATA_QUEUE_ENTRY_HEADER_SIZE + headOffset > queueSize)) {
+ return false;
+ }
+ newHeadOffset = headOffset + entrySize + DATA_QUEUE_ENTRY_HEADER_SIZE;
+ }
+ } else {
+ // empty queue
+ return false;
+ }
+
+ if (data) {
+ if (entrySize > *dataSize) {
+ // not enough space
+ return false;
+ }
+ __nochk_memcpy(data, (void *)entry->data, entrySize);
+ *dataSize = entrySize;
+ }
+
+ __c11_atomic_store((_Atomic UInt32 *)&dataQueue->head, newHeadOffset, __ATOMIC_RELEASE);
+
+ if (newHeadOffset == tailOffset) {
+ //
+ // If we are making the queue empty, then we need to make sure
+ // that either the enqueuer notices, or we notice the enqueue
+ // that raced with our making of the queue empty.
+ //
+ __c11_atomic_thread_fence(__ATOMIC_SEQ_CST);
+ }
+
+ return retVal;
}
-UInt32 IOSharedDataQueue::getQueueSize()
+UInt32
+IOSharedDataQueue::getQueueSize()
{
- if (!_reserved) {
- return 0;
- }
- return _reserved->queueSize;
+ if (!_reserved) {
+ return 0;
+ }
+ return _reserved->queueSize;
}
-Boolean IOSharedDataQueue::setQueueSize(UInt32 size)
+Boolean
+IOSharedDataQueue::setQueueSize(UInt32 size)
{
- if (!_reserved) {
- return false;
- }
- _reserved->queueSize = size;
- return true;
+ if (!_reserved) {
+ return false;
+ }
+ _reserved->queueSize = size;
+ return true;
}
OSMetaClassDefineReservedUnused(IOSharedDataQueue, 0);
projects / apple / xnu.git / blobdiff