Commit 272bce17 authored Mar 20, 2017 by Arnd Bergmann Committed by Chris Wilson Mar 21, 2017

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: 935a2f77 ("drm/i915: Add some selftests for sg_table manipulation")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: http://patchwork.freedesktop.org/patch/msgid/20170320094335.1266306-2-arnd@arndb.de

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

parent 24caf655

drivers/gpu/drm/i915/selftests/scatterlist.c

+10 −1

Original line number	Diff line number	Diff line
		@@ -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;
		}