コード例 #1
0
ファイル: ring_buffer.c プロジェクト: ayiyaliing/lis-next
/*
 *
 * hv_ringbuffer_write()
 *
 * Write to the ring buffer
 *
 */
int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info,
		    struct kvec *kv_list, u32 kv_count, bool *signal)
{
	int i = 0;
	u32 bytes_avail_towrite;
	u32 bytes_avail_toread;
	u32 totalbytes_towrite = 0;

	u32 next_write_location;
	u32 old_write;
	u64 prev_indices = 0;
	unsigned long flags;

	for (i = 0; i < kv_count; i++)
		totalbytes_towrite += kv_list[i].iov_len;

	totalbytes_towrite += sizeof(u64);

	spin_lock_irqsave(&outring_info->ring_lock, flags);

	hv_get_ringbuffer_availbytes(outring_info,
				&bytes_avail_toread,
				&bytes_avail_towrite);


	/* If there is only room for the packet, assume it is full. */
	/* Otherwise, the next time around, we think the ring buffer */
	/* is empty since the read index == write index */
	if (bytes_avail_towrite <= totalbytes_towrite) {
		spin_unlock_irqrestore(&outring_info->ring_lock, flags);
		return -EAGAIN;
	}

	/* Write to the ring buffer */
	next_write_location = hv_get_next_write_location(outring_info);

	old_write = next_write_location;

	for (i = 0; i < kv_count; i++) {
		next_write_location = hv_copyto_ringbuffer(outring_info,
						     next_write_location,
						     kv_list[i].iov_base,
						     kv_list[i].iov_len);
	}

	/* Set previous packet start */
	prev_indices = hv_get_ring_bufferindices(outring_info);

	next_write_location = hv_copyto_ringbuffer(outring_info,
					     next_write_location,
					     &prev_indices,
					     sizeof(u64));

	/* Issue a full memory barrier before updating the write index */
	mb();

	/* Now, update the write location */
	hv_set_next_write_location(outring_info, next_write_location);


	spin_unlock_irqrestore(&outring_info->ring_lock, flags);

	*signal = hv_need_to_signal(old_write, outring_info);
	return 0;
}
コード例 #2
0
ファイル: ring_buffer.c プロジェクト: 0x000000FF/Linux4Edison
	next_write_location = hv_copyto_ringbuffer(outring_info,
					     next_write_location,
					     &prev_indices,
					     sizeof(u64));

	/* Issue a full memory barrier before updating the write index */
	mb();

	/* Now, update the write location */
	hv_set_next_write_location(outring_info, next_write_location);


	spin_unlock_irqrestore(&outring_info->ring_lock, flags);

	*signal = hv_need_to_signal(old_write, outring_info);
	return 0;
}


/*
 *
 * hv_ringbuffer_peek()
 *
 * Read without advancing the read index
 *
 */
int hv_ringbuffer_peek(struct hv_ring_buffer_info *Inring_info,
		   void *Buffer, u32 buflen)
{
	u32 bytes_avail_towrite;