static void hot_add_req()

in hv_balloon.c [982:1065]

• 50 lines of code
• 10 McCabe index (conditional complexity)

static void hot_add_req(struct work_struct *dummy)
{
	struct dm_hot_add_response resp;
#ifdef CONFIG_MEMORY_HOTPLUG
	unsigned long pg_start, pfn_cnt;
	unsigned long rg_start, rg_sz;
#endif
	struct hv_dynmem_device *dm = &dm_device;

	memset(&resp, 0, sizeof(struct dm_hot_add_response));
	resp.hdr.type = DM_MEM_HOT_ADD_RESPONSE;
	resp.hdr.size = sizeof(struct dm_hot_add_response);

#ifdef CONFIG_MEMORY_HOTPLUG
	pg_start = dm->ha_wrk.ha_page_range.finfo.start_page;
	pfn_cnt = dm->ha_wrk.ha_page_range.finfo.page_cnt;

	rg_start = dm->ha_wrk.ha_region_range.finfo.start_page;
	rg_sz = dm->ha_wrk.ha_region_range.finfo.page_cnt;

	if ((rg_start == 0) && (!dm->host_specified_ha_region)) {
		unsigned long region_size;
		unsigned long region_start;

		/*
		 * The host has not specified the hot-add region.
		 * Based on the hot-add page range being specified,
		 * compute a hot-add region that can cover the pages
		 * that need to be hot-added while ensuring the alignment
		 * and size requirements of Linux as it relates to hot-add.
		 */
		region_size = (pfn_cnt / HA_CHUNK) * HA_CHUNK;
		if (pfn_cnt % HA_CHUNK)
			region_size += HA_CHUNK;

		region_start = (pg_start / HA_CHUNK) * HA_CHUNK;

		rg_start = region_start;
		rg_sz = region_size;
	}

	if (do_hot_add)
		resp.page_count = process_hot_add(pg_start, pfn_cnt,
						rg_start, rg_sz);

	dm->num_pages_added += resp.page_count;
#endif
	/*
	 * The result field of the response structure has the
	 * following semantics:
	 *
	 * 1. If all or some pages hot-added: Guest should return success.
	 *
	 * 2. If no pages could be hot-added:
	 *
	 * If the guest returns success, then the host
	 * will not attempt any further hot-add operations. This
	 * signifies a permanent failure.
	 *
	 * If the guest returns failure, then this failure will be
	 * treated as a transient failure and the host may retry the
	 * hot-add operation after some delay.
	 */
	if (resp.page_count > 0)
		resp.result = 1;
	else if (!do_hot_add)
		resp.result = 1;
	else
		resp.result = 0;

	if (!do_hot_add || resp.page_count == 0) {
		if (!allow_hibernation)
			pr_err("Memory hot add failed\n");
		else
			pr_info("Ignore hot-add request!\n");
	}

	dm->state = DM_INITIALIZED;
	resp.hdr.trans_id = atomic_inc_return(&trans_id);
	vmbus_sendpacket(dm->dev->channel, &resp,
			sizeof(struct dm_hot_add_response),
			(unsigned long)NULL,
			VM_PKT_DATA_INBAND, 0);
}