When igt_random_offset() is a given a range of [0, PAGE_SIZE], it is
allowed to return 0. However, attempting to use a size of 0 for the
igt_lmem_write_cpu() byte poking, leads to call igt_random_offset() with
a range of [offset, offset + 0] and ask it to find a length of 4 within
it. This triggers the bug on that the requested length should fit within
the range!
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Matthew Auld <matthew.auld@xxxxxxxxx>
---
I feel into the same trap of not fixing up the random return of 0
---
drivers/gpu/drm/i915/selftests/intel_memory_region.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/selftests/intel_memory_region.c b/drivers/gpu/drm/i915/selftests/intel_memory_region.c
index 6e80d99048e4..54e683bb220b 100644
--- a/drivers/gpu/drm/i915/selftests/intel_memory_region.c
+++ b/drivers/gpu/drm/i915/selftests/intel_memory_region.c
@@ -522,9 +522,10 @@ static int igt_lmem_write_cpu(void *arg)
goto out_unpin;
}
- /* We want to throw in a random width/align */
- bytes[0] = igt_random_offset(&prng, 0, PAGE_SIZE, sizeof(u32),
- sizeof(u32));
+ /* A random multiple of u32, picked between [64, PAGE_SIZE - 64] */
+ bytes[0] = 1 + prandom_u32_state(&prng);
+ bytes[0] = round_up(bytes[0], 64) & (PAGE_SIZE - 1);
+ GEM_BUG_ON(!IS_ALIGNED(bytes[0], sizeof(u32)));
i = 0;
do {
--
2.20.1
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