static int get_free_page_and_send()

in virtio_balloon.c [621:666]

• 32 lines of code
• 5 McCabe index (conditional complexity)

static int get_free_page_and_send(struct virtio_balloon *vb)
{
	struct virtqueue *vq = vb->free_page_vq;
	struct page *page;
	struct scatterlist sg;
	int err, unused;
	void *p;

	/* Detach all the used buffers from the vq */
	while (virtqueue_get_buf(vq, &unused))
		;

	page = alloc_pages(VIRTIO_BALLOON_FREE_PAGE_ALLOC_FLAG,
			   VIRTIO_BALLOON_HINT_BLOCK_ORDER);
	/*
	 * When the allocation returns NULL, it indicates that we have got all
	 * the possible free pages, so return -EINTR to stop.
	 */
	if (!page)
		return -EINTR;

	p = page_address(page);
	sg_init_one(&sg, p, VIRTIO_BALLOON_HINT_BLOCK_BYTES);
	/* There is always 1 entry reserved for the cmd id to use. */
	if (vq->num_free > 1) {
		err = virtqueue_add_inbuf(vq, &sg, 1, p, GFP_KERNEL);
		if (unlikely(err)) {
			free_pages((unsigned long)p,
				   VIRTIO_BALLOON_HINT_BLOCK_ORDER);
			return err;
		}
		virtqueue_kick(vq);
		spin_lock_irq(&vb->free_page_list_lock);
		balloon_page_push(&vb->free_page_list, page);
		vb->num_free_page_blocks++;
		spin_unlock_irq(&vb->free_page_list_lock);
	} else {
		/*
		 * The vq has no available entry to add this page block, so
		 * just free it.
		 */
		free_pages((unsigned long)p, VIRTIO_BALLOON_HINT_BLOCK_ORDER);
	}

	return 0;
}