Commit ea2735ce authored by Carlos Llamas's avatar Carlos Llamas Committed by Greg Kroah-Hartman
Browse files

binder: refactor page range allocation 



Instead of looping through the page range twice to first determine if
the mmap lock is required, simply do it per-page as needed. Split out
all this logic into a separate binder_install_single_page() function.

Reviewed-by: default avatarAlice Ryhl <aliceryhl@google.com>
Signed-off-by: default avatarCarlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-17-cmllamas@google.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent cbc174a6

drivers/android/binder_alloc.c

+47 −60
Original line number Diff line number Diff line
@@ -199,14 +199,51 @@ static void binder_free_page_range(struct binder_alloc *alloc, 
	}

}



static int binder_install_single_page(struct binder_alloc *alloc,

				      struct binder_lru_page *lru_page,

				      unsigned long addr)

{

	struct page *page;

	int ret = 0;



	if (!mmget_not_zero(alloc->mm))

		return -ESRCH;



	mmap_write_lock(alloc->mm);

	if (!alloc->vma) {

		pr_err("%d: %s failed, no vma\n", alloc->pid, __func__);

		ret = -ESRCH;

		goto out;

	}



	page = alloc_page(GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO);

	if (!page) {

		pr_err("%d: failed to allocate page\n", alloc->pid);

		ret = -ENOMEM;

		goto out;

	}



	ret = vm_insert_page(alloc->vma, addr, page);

	if (ret) {

		pr_err("%d: %s failed to insert page at %lx with %d\n",

		       alloc->pid, __func__, addr, ret);

		__free_page(page);

		ret = -ENOMEM;

		goto out;

	}



	lru_page->page_ptr = page;

out:

	mmap_write_unlock(alloc->mm);

	mmput_async(alloc->mm);

	return ret;

}



static int binder_allocate_page_range(struct binder_alloc *alloc,

				      unsigned long start, unsigned long end)

{

	struct vm_area_struct *vma = NULL;

	struct binder_lru_page *page;

	struct mm_struct *mm = NULL;

	unsigned long page_addr;

	bool need_mm = false;



	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,

			   "%d: allocate pages %lx-%lx\n",
@@ -218,32 +255,9 @@ static int binder_allocate_page_range(struct binder_alloc *alloc, 
	trace_binder_update_page_range(alloc, true, start, end);



	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->mm))

		mm = alloc->mm;



	if (mm) {

		mmap_write_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;

		unsigned long index;

		bool on_lru;

		size_t index;

		int ret;



		index = (page_addr - alloc->buffer) / PAGE_SIZE;

		page = &alloc->pages[index];
@@ -258,26 +272,15 @@ static int binder_allocate_page_range(struct binder_alloc *alloc, 
			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 %lx\n",

			       alloc->pid, page_addr);

			goto err_alloc_page_failed;

		}



		page->alloc = alloc;

		INIT_LIST_HEAD(&page->lru);



		ret = vm_insert_page(vma, page_addr, page->page_ptr);

		ret = binder_install_single_page(alloc, page, page_addr);

		if (ret) {

			pr_err("%d: binder_alloc_buf failed to map page at %lx in userspace\n",

			       alloc->pid, page_addr);

			goto err_vm_insert_page_failed;

			binder_free_page_range(alloc, start, page_addr);

			return ret;

		}



		if (index + 1 > alloc->pages_high)
@@ -285,24 +288,8 @@ static int binder_allocate_page_range(struct binder_alloc *alloc, 


		trace_binder_alloc_page_end(alloc, index);

	}

	if (mm) {

		mmap_write_unlock(mm);

		mmput_async(mm);

	}

	return 0;



err_vm_insert_page_failed:

	__free_page(page->page_ptr);

	page->page_ptr = NULL;

err_alloc_page_failed:

err_page_ptr_cleared:

	binder_free_page_range(alloc, start, page_addr);

err_no_vma:

	if (mm) {

		mmap_write_unlock(mm);

		mmput_async(mm);

	}

	return vma ? -ENOMEM : -ESRCH;

	return 0;

}



static inline void binder_alloc_set_vma(struct binder_alloc *alloc,