From 272bce17cc3ef4629e28c38324d81ca72a862115 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Mon, 20 Mar 2017 10:40:28 +0100 Subject: [PATCH] drm/i915: split out check for noncontiguous pfn range We get a warning with gcc-7 about a pointless comparison when using a linear memmap: drivers/gpu/drm/i915/selftests/scatterlist.c: In function 'alloc_table': drivers/gpu/drm/i915/selftests/scatterlist.c:219:66: error: self-comparison always evaluates to false [-Werror=tautological-compare] Splitting out the comparison into a separate function avoids the warning and makes it slightly more obvious what happens. Fixes: 935a2f776aa5 ("drm/i915: Add some selftests for sg_table manipulation") Signed-off-by: Arnd Bergmann Link: http://patchwork.freedesktop.org/patch/msgid/20170320094335.1266306-2-arnd@arndb.de Reviewed-by: Chris Wilson Signed-off-by: Chris Wilson --- drivers/gpu/drm/i915/selftests/scatterlist.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/selftests/scatterlist.c b/drivers/gpu/drm/i915/selftests/scatterlist.c index eb2cda8e2b9f..1cc5d2931753 100644 --- a/drivers/gpu/drm/i915/selftests/scatterlist.c +++ b/drivers/gpu/drm/i915/selftests/scatterlist.c @@ -189,6 +189,13 @@ static unsigned int random(unsigned long n, return 1 + (prandom_u32_state(rnd) % 1024); } +static inline bool page_contiguous(struct page *first, + struct page *last, + unsigned long npages) +{ + return first + npages == last; +} + static int alloc_table(struct pfn_table *pt, unsigned long count, unsigned long max, npages_fn_t npages_fn, @@ -216,7 +223,9 @@ static int alloc_table(struct pfn_table *pt, unsigned long npages = npages_fn(n, count, rnd); /* Nobody expects the Sparse Memmap! */ - if (pfn_to_page(pfn + npages) != pfn_to_page(pfn) + npages) { + if (!page_contiguous(pfn_to_page(pfn), + pfn_to_page(pfn + npages), + npages)) { sg_free_table(&pt->st); return -ENOSPC; } -- 2.20.1