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/**
* Copyright (c) 2010-2012 Broadcom. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions, and the following disclaimer,
* without modification.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The names of the above-listed copyright holders may not be used
* to endorse or promote products derived from this software without
* specific prior written permission.
*
* ALTERNATIVELY, this software may be distributed under the terms of the
* GNU General Public License ("GPL") version 2, as published by the Free
* Software Foundation.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "vchiq_util.h"
#include "vchiq_killable.h"
static inline int is_pow2(int i)
{
return i && !(i & (i - 1));
}
int vchiu_queue_init(VCHIU_QUEUE_T *queue, int size)
{
WARN_ON(!is_pow2(size));
queue->size = size;
queue->read = 0;
queue->write = 0;
queue->initialized = 1;
sema_init(&queue->pop, 0);
sema_init(&queue->push, 0);
queue->storage = kzalloc(size * sizeof(VCHIQ_HEADER_T *), GFP_KERNEL);
if (queue->storage == NULL) {
vchiu_queue_delete(queue);
return 0;
}
return 1;
}
void vchiu_queue_delete(VCHIU_QUEUE_T *queue)
{
kfree(queue->storage);
}
int vchiu_queue_is_empty(VCHIU_QUEUE_T *queue)
{
return queue->read == queue->write;
}
int vchiu_queue_is_full(VCHIU_QUEUE_T *queue)
{
return queue->write == queue->read + queue->size;
}
void vchiu_queue_push(VCHIU_QUEUE_T *queue, VCHIQ_HEADER_T *header)
{
if (!queue->initialized)
return;
while (queue->write == queue->read + queue->size) {
if (down_interruptible(&queue->pop) != 0) {
flush_signals(current);
}
}
/*
* Write to queue->storage must be visible after read from
* queue->read
*/
smp_mb();
queue->storage[queue->write & (queue->size - 1)] = header;
/*
* Write to queue->storage must be visible before write to
* queue->write
*/
smp_wmb();
queue->write++;
up(&queue->push);
}
VCHIQ_HEADER_T *vchiu_queue_peek(VCHIU_QUEUE_T *queue)
{
while (queue->write == queue->read) {
if (down_interruptible(&queue->push) != 0) {
flush_signals(current);
}
}
up(&queue->push); // We haven't removed anything from the queue.
/*
* Read from queue->storage must be visible after read from
* queue->write
*/
smp_rmb();
return queue->storage[queue->read & (queue->size - 1)];
}
VCHIQ_HEADER_T *vchiu_queue_pop(VCHIU_QUEUE_T *queue)
{
VCHIQ_HEADER_T *header;
while (queue->write == queue->read) {
if (down_interruptible(&queue->push) != 0) {
flush_signals(current);
}
}
/*
* Read from queue->storage must be visible after read from
* queue->write
*/
smp_rmb();
header = queue->storage[queue->read & (queue->size - 1)];
/*
* Read from queue->storage must be visible before write to
* queue->read
*/
smp_mb();
queue->read++;
up(&queue->pop);
return header;
}
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