static vm_fault_t uio_vma_fault()

in uio.c [669:708]

• 30 lines of code
• 4 McCabe index (conditional complexity)

static vm_fault_t uio_vma_fault(struct vm_fault *vmf)
{
	struct uio_device *idev = vmf->vma->vm_private_data;
	struct page *page;
	unsigned long offset;
	void *addr;
	vm_fault_t ret = 0;
	int mi;

	mutex_lock(&idev->info_lock);
	if (!idev->info) {
		ret = VM_FAULT_SIGBUS;
		goto out;
	}

	mi = uio_find_mem_index(vmf->vma);
	if (mi < 0) {
		ret = VM_FAULT_SIGBUS;
		goto out;
	}

	/*
	 * We need to subtract mi because userspace uses offset = N*PAGE_SIZE
	 * to use mem[N].
	 */
	offset = (vmf->pgoff - mi) << PAGE_SHIFT;

	addr = (void *)(unsigned long)idev->info->mem[mi].addr + offset;
	if (idev->info->mem[mi].memtype == UIO_MEM_LOGICAL)
		page = virt_to_page(addr);
	else
		page = vmalloc_to_page(addr);
	get_page(page);
	vmf->page = page;

out:
	mutex_unlock(&idev->info_lock);

	return ret;
}