static int create_gpadl_header()

in channel.c [309:444]

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

static int create_gpadl_header(enum hv_gpadl_type type, void *kbuffer,
			       u32 size, u32 send_offset,
			       struct vmbus_channel_msginfo **msginfo)
{
	int i;
	int pagecount;
	struct vmbus_channel_gpadl_header *gpadl_header;
	struct vmbus_channel_gpadl_body *gpadl_body;
	struct vmbus_channel_msginfo *msgheader;
	struct vmbus_channel_msginfo *msgbody = NULL;
	u32 msgsize;

	int pfnsum, pfncount, pfnleft, pfncurr, pfnsize;

	pagecount = hv_gpadl_size(type, size) >> HV_HYP_PAGE_SHIFT;

	/* do we need a gpadl body msg */
	pfnsize = MAX_SIZE_CHANNEL_MESSAGE -
		  sizeof(struct vmbus_channel_gpadl_header) -
		  sizeof(struct gpa_range);
	pfncount = pfnsize / sizeof(u64);

	if (pagecount > pfncount) {
		/* we need a gpadl body */
		/* fill in the header */
		msgsize = sizeof(struct vmbus_channel_msginfo) +
			  sizeof(struct vmbus_channel_gpadl_header) +
			  sizeof(struct gpa_range) + pfncount * sizeof(u64);
		msgheader =  kzalloc(msgsize, GFP_KERNEL);
		if (!msgheader)
			goto nomem;

		INIT_LIST_HEAD(&msgheader->submsglist);
		msgheader->msgsize = msgsize;

		gpadl_header = (struct vmbus_channel_gpadl_header *)
			msgheader->msg;
		gpadl_header->rangecount = 1;
		gpadl_header->range_buflen = sizeof(struct gpa_range) +
					 pagecount * sizeof(u64);
		gpadl_header->range[0].byte_offset = 0;
		gpadl_header->range[0].byte_count = hv_gpadl_size(type, size);
		for (i = 0; i < pfncount; i++)
			gpadl_header->range[0].pfn_array[i] = hv_gpadl_hvpfn(
				type, kbuffer, size, send_offset, i);
		*msginfo = msgheader;

		pfnsum = pfncount;
		pfnleft = pagecount - pfncount;

		/* how many pfns can we fit */
		pfnsize = MAX_SIZE_CHANNEL_MESSAGE -
			  sizeof(struct vmbus_channel_gpadl_body);
		pfncount = pfnsize / sizeof(u64);

		/* fill in the body */
		while (pfnleft) {
			if (pfnleft > pfncount)
				pfncurr = pfncount;
			else
				pfncurr = pfnleft;

			msgsize = sizeof(struct vmbus_channel_msginfo) +
				  sizeof(struct vmbus_channel_gpadl_body) +
				  pfncurr * sizeof(u64);
			msgbody = kzalloc(msgsize, GFP_KERNEL);

			if (!msgbody) {
				struct vmbus_channel_msginfo *pos = NULL;
				struct vmbus_channel_msginfo *tmp = NULL;
				/*
				 * Free up all the allocated messages.
				 */
				list_for_each_entry_safe(pos, tmp,
					&msgheader->submsglist,
					msglistentry) {

					list_del(&pos->msglistentry);
					kfree(pos);
				}

				goto nomem;
			}

			msgbody->msgsize = msgsize;
			gpadl_body =
				(struct vmbus_channel_gpadl_body *)msgbody->msg;

			/*
			 * Gpadl is u32 and we are using a pointer which could
			 * be 64-bit
			 * This is governed by the guest/host protocol and
			 * so the hypervisor guarantees that this is ok.
			 */
			for (i = 0; i < pfncurr; i++)
				gpadl_body->pfn[i] = hv_gpadl_hvpfn(type,
					kbuffer, size, send_offset, pfnsum + i);

			/* add to msg header */
			list_add_tail(&msgbody->msglistentry,
				      &msgheader->submsglist);
			pfnsum += pfncurr;
			pfnleft -= pfncurr;
		}
	} else {
		/* everything fits in a header */
		msgsize = sizeof(struct vmbus_channel_msginfo) +
			  sizeof(struct vmbus_channel_gpadl_header) +
			  sizeof(struct gpa_range) + pagecount * sizeof(u64);
		msgheader = kzalloc(msgsize, GFP_KERNEL);
		if (msgheader == NULL)
			goto nomem;

		INIT_LIST_HEAD(&msgheader->submsglist);
		msgheader->msgsize = msgsize;

		gpadl_header = (struct vmbus_channel_gpadl_header *)
			msgheader->msg;
		gpadl_header->rangecount = 1;
		gpadl_header->range_buflen = sizeof(struct gpa_range) +
					 pagecount * sizeof(u64);
		gpadl_header->range[0].byte_offset = 0;
		gpadl_header->range[0].byte_count = hv_gpadl_size(type, size);
		for (i = 0; i < pagecount; i++)
			gpadl_header->range[0].pfn_array[i] = hv_gpadl_hvpfn(
				type, kbuffer, size, send_offset, i);

		*msginfo = msgheader;
	}

	return 0;
nomem:
	kfree(msgheader);
	kfree(msgbody);
	return -ENOMEM;
}