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Commit 7fb9ee5d authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915: Simplify guard logic for setup_scratch_page() 



Older gcc is complaining it can't follow the guards and thinks that
addr may be used uninitialised

In the process, we can simplify down to one loop,
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-131 (-131)
Function                                     old     new   delta
setup_scratch_page                           545     414    -131

Reported-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: default avatarMatthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180129102840.19901-1-chris@chris-wilson.co.uk
parent 74c0167f

drivers/gpu/drm/i915/i915_gem_gtt.c

+33 −36
Original line number Diff line number Diff line
@@ -543,9 +543,7 @@ static void fill_page_dma_32(struct i915_address_space *vm, 
static int

setup_scratch_page(struct i915_address_space *vm, gfp_t gfp)

{

	struct page *page = NULL;

	dma_addr_t addr;

	int order;

	unsigned long size;



	/*

	 * In order to utilize 64K pages for an object with a size < 2M, we will
@@ -559,48 +557,47 @@ setup_scratch_page(struct i915_address_space *vm, gfp_t gfp) 
	 * TODO: we should really consider write-protecting the scratch-page and

	 * sharing between ppgtt

	 */

	size = I915_GTT_PAGE_SIZE_4K;

	if (i915_vm_is_48bit(vm) &&

	    HAS_PAGE_SIZES(vm->i915, I915_GTT_PAGE_SIZE_64K)) {

		order = get_order(I915_GTT_PAGE_SIZE_64K);

		page = alloc_pages(gfp | __GFP_ZERO | __GFP_NOWARN, order);

		if (page) {

			addr = dma_map_page(vm->dma, page, 0,

					    I915_GTT_PAGE_SIZE_64K,

					    PCI_DMA_BIDIRECTIONAL);

			if (unlikely(dma_mapping_error(vm->dma, addr))) {

				__free_pages(page, order);

				page = NULL;

		size = I915_GTT_PAGE_SIZE_64K;

		gfp |= __GFP_NOWARN;

	}

	gfp |= __GFP_ZERO | __GFP_RETRY_MAYFAIL;



			if (!IS_ALIGNED(addr, I915_GTT_PAGE_SIZE_64K)) {

				dma_unmap_page(vm->dma, addr,

					       I915_GTT_PAGE_SIZE_64K,

					       PCI_DMA_BIDIRECTIONAL);

				__free_pages(page, order);

				page = NULL;

			}

		}

	}

	do {

		int order = get_order(size);

		struct page *page;

		dma_addr_t addr;



	if (!page) {

		order = 0;

		page = alloc_page(gfp | __GFP_ZERO);

		page = alloc_pages(gfp, order);

		if (unlikely(!page))

			return -ENOMEM;

			goto skip;



		addr = dma_map_page(vm->dma, page, 0, PAGE_SIZE,

		addr = dma_map_page(vm->dma, page, 0, size,

				    PCI_DMA_BIDIRECTIONAL);

		if (unlikely(dma_mapping_error(vm->dma, addr))) {

			__free_page(page);

			return -ENOMEM;

		}

	}

		if (unlikely(dma_mapping_error(vm->dma, addr)))

			goto free_page;



		if (unlikely(!IS_ALIGNED(addr, size)))

			goto unmap_page;



		vm->scratch_page.page = page;

		vm->scratch_page.daddr = addr;

		vm->scratch_page.order = order;



		return 0;



unmap_page:

		dma_unmap_page(vm->dma, addr, size, PCI_DMA_BIDIRECTIONAL);

free_page:

		__free_pages(page, order);

skip:

		if (size == I915_GTT_PAGE_SIZE_4K)

			return -ENOMEM;



		size = I915_GTT_PAGE_SIZE_4K;

		gfp &= ~__GFP_NOWARN;

	} while (1);

}



static void cleanup_scratch_page(struct i915_address_space *vm)