static int virtio_mem_init_hotplug()

in virtio_mem.c [2456:2579]

• 89 lines of code
• 17 McCabe index (conditional complexity)

static int virtio_mem_init_hotplug(struct virtio_mem *vm)
{
	const struct range pluggable_range = mhp_get_pluggable_range(true);
	uint64_t unit_pages, sb_size, addr;
	int rc;

	/* bad device setup - warn only */
	if (!IS_ALIGNED(vm->addr, memory_block_size_bytes()))
		dev_warn(&vm->vdev->dev,
			 "The alignment of the physical start address can make some memory unusable.\n");
	if (!IS_ALIGNED(vm->addr + vm->region_size, memory_block_size_bytes()))
		dev_warn(&vm->vdev->dev,
			 "The alignment of the physical end address can make some memory unusable.\n");
	if (vm->addr < pluggable_range.start ||
	    vm->addr + vm->region_size - 1 > pluggable_range.end)
		dev_warn(&vm->vdev->dev,
			 "Some device memory is not addressable/pluggable. This can make some memory unusable.\n");

	/* Prepare the offline threshold - make sure we can add two blocks. */
	vm->offline_threshold = max_t(uint64_t, 2 * memory_block_size_bytes(),
				      VIRTIO_MEM_DEFAULT_OFFLINE_THRESHOLD);

	/*
	 * We want subblocks to span at least MAX_ORDER_NR_PAGES and
	 * pageblock_nr_pages pages. This:
	 * - Is required for now for alloc_contig_range() to work reliably -
	 *   it doesn't properly handle smaller granularity on ZONE_NORMAL.
	 */
	sb_size = max_t(uint64_t, MAX_ORDER_NR_PAGES,
			pageblock_nr_pages) * PAGE_SIZE;
	sb_size = max_t(uint64_t, vm->device_block_size, sb_size);

	if (sb_size < memory_block_size_bytes() && !force_bbm) {
		/* SBM: At least two subblocks per Linux memory block. */
		vm->in_sbm = true;
		vm->sbm.sb_size = sb_size;
		vm->sbm.sbs_per_mb = memory_block_size_bytes() /
				     vm->sbm.sb_size;

		/* Round up to the next full memory block */
		addr = max_t(uint64_t, vm->addr, pluggable_range.start) +
		       memory_block_size_bytes() - 1;
		vm->sbm.first_mb_id = virtio_mem_phys_to_mb_id(addr);
		vm->sbm.next_mb_id = vm->sbm.first_mb_id;
	} else {
		/* BBM: At least one Linux memory block. */
		vm->bbm.bb_size = max_t(uint64_t, vm->device_block_size,
					memory_block_size_bytes());

		if (bbm_block_size) {
			if (!is_power_of_2(bbm_block_size)) {
				dev_warn(&vm->vdev->dev,
					 "bbm_block_size is not a power of 2");
			} else if (bbm_block_size < vm->bbm.bb_size) {
				dev_warn(&vm->vdev->dev,
					 "bbm_block_size is too small");
			} else {
				vm->bbm.bb_size = bbm_block_size;
			}
		}

		/* Round up to the next aligned big block */
		addr = max_t(uint64_t, vm->addr, pluggable_range.start) +
		       vm->bbm.bb_size - 1;
		vm->bbm.first_bb_id = virtio_mem_phys_to_bb_id(vm, addr);
		vm->bbm.next_bb_id = vm->bbm.first_bb_id;

		/* Make sure we can add two big blocks. */
		vm->offline_threshold = max_t(uint64_t, 2 * vm->bbm.bb_size,
					      vm->offline_threshold);
	}

	dev_info(&vm->vdev->dev, "memory block size: 0x%lx",
		 memory_block_size_bytes());
	if (vm->in_sbm)
		dev_info(&vm->vdev->dev, "subblock size: 0x%llx",
			 (unsigned long long)vm->sbm.sb_size);
	else
		dev_info(&vm->vdev->dev, "big block size: 0x%llx",
			 (unsigned long long)vm->bbm.bb_size);

	/* create the parent resource for all memory */
	rc = virtio_mem_create_resource(vm);
	if (rc)
		return rc;

	/* use a single dynamic memory group to cover the whole memory device */
	if (vm->in_sbm)
		unit_pages = PHYS_PFN(memory_block_size_bytes());
	else
		unit_pages = PHYS_PFN(vm->bbm.bb_size);
	rc = memory_group_register_dynamic(vm->nid, unit_pages);
	if (rc < 0)
		goto out_del_resource;
	vm->mgid = rc;

	/*
	 * If we still have memory plugged, we have to unplug all memory first.
	 * Registering our parent resource makes sure that this memory isn't
	 * actually in use (e.g., trying to reload the driver).
	 */
	if (vm->plugged_size) {
		vm->unplug_all_required = true;
		dev_info(&vm->vdev->dev, "unplugging all memory is required\n");
	}

	/* register callbacks */
	vm->memory_notifier.notifier_call = virtio_mem_memory_notifier_cb;
	rc = register_memory_notifier(&vm->memory_notifier);
	if (rc)
		goto out_unreg_group;
	rc = register_virtio_mem_device(vm);
	if (rc)
		goto out_unreg_mem;

	return 0;
out_unreg_mem:
	unregister_memory_notifier(&vm->memory_notifier);
out_unreg_group:
	memory_group_unregister(vm->mgid);
out_del_resource:
	virtio_mem_delete_resource(vm);
	return rc;
}