static int virtio_mem_sbm_plug_request()

in virtio_mem.c [1694:1755]

• 46 lines of code
• 12 McCabe index (conditional complexity)

static int virtio_mem_sbm_plug_request(struct virtio_mem *vm, uint64_t diff)
{
	const int mb_states[] = {
		VIRTIO_MEM_SBM_MB_KERNEL_PARTIAL,
		VIRTIO_MEM_SBM_MB_MOVABLE_PARTIAL,
		VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL,
	};
	uint64_t nb_sb = diff / vm->sbm.sb_size;
	unsigned long mb_id;
	int rc, i;

	if (!nb_sb)
		return 0;

	/* Don't race with onlining/offlining */
	mutex_lock(&vm->hotplug_mutex);

	for (i = 0; i < ARRAY_SIZE(mb_states); i++) {
		virtio_mem_sbm_for_each_mb(vm, mb_id, mb_states[i]) {
			rc = virtio_mem_sbm_plug_any_sb(vm, mb_id, &nb_sb);
			if (rc || !nb_sb)
				goto out_unlock;
			cond_resched();
		}
	}

	/*
	 * We won't be working on online/offline memory blocks from this point,
	 * so we can't race with memory onlining/offlining. Drop the mutex.
	 */
	mutex_unlock(&vm->hotplug_mutex);

	/* Try to plug and add unused blocks */
	virtio_mem_sbm_for_each_mb(vm, mb_id, VIRTIO_MEM_SBM_MB_UNUSED) {
		if (!virtio_mem_could_add_memory(vm, memory_block_size_bytes()))
			return -ENOSPC;

		rc = virtio_mem_sbm_plug_and_add_mb(vm, mb_id, &nb_sb);
		if (rc || !nb_sb)
			return rc;
		cond_resched();
	}

	/* Try to prepare, plug and add new blocks */
	while (nb_sb) {
		if (!virtio_mem_could_add_memory(vm, memory_block_size_bytes()))
			return -ENOSPC;

		rc = virtio_mem_sbm_prepare_next_mb(vm, &mb_id);
		if (rc)
			return rc;
		rc = virtio_mem_sbm_plug_and_add_mb(vm, mb_id, &nb_sb);
		if (rc)
			return rc;
		cond_resched();
	}

	return 0;
out_unlock:
	mutex_unlock(&vm->hotplug_mutex);
	return rc;
}