static int binder_update_page_range()

in binder_alloc.c [181:310]

• 106 lines of code
• 23 McCabe index (conditional complexity)

static int binder_update_page_range(struct binder_alloc *alloc, int allocate,
				    void __user *start, void __user *end)
{
	void __user *page_addr;
	unsigned long user_page_addr;
	struct binder_lru_page *page;
	struct vm_area_struct *vma = NULL;
	struct mm_struct *mm = NULL;
	bool need_mm = false;

	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
		     "%d: %s pages %pK-%pK\n", alloc->pid,
		     allocate ? "allocate" : "free", start, end);

	if (end <= start)
		return 0;

	trace_binder_update_page_range(alloc, allocate, start, end);

	if (allocate == 0)
		goto free_range;

	for (page_addr = start; page_addr < end; page_addr += PAGE_SIZE) {
		page = &alloc->pages[(page_addr - alloc->buffer) / PAGE_SIZE];
		if (!page->page_ptr) {
			need_mm = true;
			break;
		}
	}

	if (need_mm && mmget_not_zero(alloc->vma_vm_mm))
		mm = alloc->vma_vm_mm;

	if (mm) {
		mmap_read_lock(mm);
		vma = alloc->vma;
	}

	if (!vma && need_mm) {
		binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
				   "%d: binder_alloc_buf failed to map pages in userspace, no vma\n",
				   alloc->pid);
		goto err_no_vma;
	}

	for (page_addr = start; page_addr < end; page_addr += PAGE_SIZE) {
		int ret;
		bool on_lru;
		size_t index;

		index = (page_addr - alloc->buffer) / PAGE_SIZE;
		page = &alloc->pages[index];

		if (page->page_ptr) {
			trace_binder_alloc_lru_start(alloc, index);

			on_lru = list_lru_del(&binder_alloc_lru, &page->lru);
			WARN_ON(!on_lru);

			trace_binder_alloc_lru_end(alloc, index);
			continue;
		}

		if (WARN_ON(!vma))
			goto err_page_ptr_cleared;

		trace_binder_alloc_page_start(alloc, index);
		page->page_ptr = alloc_page(GFP_KERNEL |
					    __GFP_HIGHMEM |
					    __GFP_ZERO);
		if (!page->page_ptr) {
			pr_err("%d: binder_alloc_buf failed for page at %pK\n",
				alloc->pid, page_addr);
			goto err_alloc_page_failed;
		}
		page->alloc = alloc;
		INIT_LIST_HEAD(&page->lru);

		user_page_addr = (uintptr_t)page_addr;
		ret = vm_insert_page(vma, user_page_addr, page[0].page_ptr);
		if (ret) {
			pr_err("%d: binder_alloc_buf failed to map page at %lx in userspace\n",
			       alloc->pid, user_page_addr);
			goto err_vm_insert_page_failed;
		}

		if (index + 1 > alloc->pages_high)
			alloc->pages_high = index + 1;

		trace_binder_alloc_page_end(alloc, index);
	}
	if (mm) {
		mmap_read_unlock(mm);
		mmput(mm);
	}
	return 0;

free_range:
	for (page_addr = end - PAGE_SIZE; 1; page_addr -= PAGE_SIZE) {
		bool ret;
		size_t index;

		index = (page_addr - alloc->buffer) / PAGE_SIZE;
		page = &alloc->pages[index];

		trace_binder_free_lru_start(alloc, index);

		ret = list_lru_add(&binder_alloc_lru, &page->lru);
		WARN_ON(!ret);

		trace_binder_free_lru_end(alloc, index);
		if (page_addr == start)
			break;
		continue;

err_vm_insert_page_failed:
		__free_page(page->page_ptr);
		page->page_ptr = NULL;
err_alloc_page_failed:
err_page_ptr_cleared:
		if (page_addr == start)
			break;
	}
err_no_vma:
	if (mm) {
		mmap_read_unlock(mm);
		mmput(mm);
	}
	return vma ? -ENOMEM : -ESRCH;
}