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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: 935a2f776a ("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>
This commit is contained in:
Arnd Bergmann 2017-03-20 10:40:28 +01:00 committed by Chris Wilson
parent 24caf65593
commit 272bce17cc
1 changed files with 10 additions and 1 deletions
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11
drivers/gpu/drm/i915/selftests/scatterlist.c
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@ -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;
}