From 7fb9ee5db24a5892d3af8487de39d7b4a7fc2ea8 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Mon, 29 Jan 2018 10:28:40 +0000 Subject: [PATCH] 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: Geert Uytterhoeven Signed-off-by: Chris Wilson Cc: Matthew Auld Reviewed-by: Matthew Auld Link: https://patchwork.freedesktop.org/patch/msgid/20180129102840.19901-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/i915_gem_gtt.c | 69 ++++++++++++++--------------- 1 file changed, 33 insertions(+), 36 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c index be227512430a..b65426c0457d 100644 --- a/drivers/gpu/drm/i915/i915_gem_gtt.c +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c @@ -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; - } - - 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; - } - } + size = I915_GTT_PAGE_SIZE_64K; + gfp |= __GFP_NOWARN; } + gfp |= __GFP_ZERO | __GFP_RETRY_MAYFAIL; - if (!page) { - order = 0; - page = alloc_page(gfp | __GFP_ZERO); + do { + int order = get_order(size); + struct page *page; + dma_addr_t addr; + + 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; - vm->scratch_page.page = page; - vm->scratch_page.daddr = addr; - vm->scratch_page.order = order; + if (unlikely(!IS_ALIGNED(addr, size))) + goto unmap_page; - return 0; + 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) -- 2.30.2