[PATCH] bitmap: Properly initialise destination bitmap for scatter & gather test

["Christophe Leroy (CS GROUP)" <chleroy@kernel.org>]

Erhard reports failure of bitmap tests on powerpc:

  test_bitmap: loaded.
  test_bitmap: [lib/test_bitmap.c:397] bitmaps contents differ: expected "1,3-4,9", got "1,3-4,9,65-71,73-79,81-87,89-95,97-99"
  test_bitmap: parselist('0-2047:128/256'):    912
  test_bitmap: scnprintf("%*pbl", '0-32767'):    5977
  test_bitmap: test_bitmap_read_perf:        1191082
  test_bitmap: test_bitmap_write_perf:        1270153
  test_bitmap: failed 1 out of 208655 tests

The happens mainly when CONFIG_INIT_STACK_ALL_PATTERN is set.

Commit 6b5a4b687367 ("bitmap: Add test for out-of-boundary
modifications for scatter & gather") extended the test to
out-of-boundary bits, but those bits where left uninitialised.

Properly initialise the entire result bitmap before the test.

Reported-by: Erhard Furtner <erhard_f@mailbox.org>
Closes: https://lore.kernel.org/all/ca3547ae-8b79-43a2-a758-23ec980bfd9a@mailbox.org
Fixes: 6b5a4b687367 ("bitmap: Add test for out-of-boundary modifications for scatter & gather")
Signed-off-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
---
 lib/test_bitmap.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c
index 69813c10e6c0..448c3eb48a4a 100644
--- a/lib/test_bitmap.c
+++ b/lib/test_bitmap.c
@@ -392,6 +392,7 @@ static void __init test_bitmap_sg(void)
 
 	/* Scatter/gather relationship */
 	bitmap_zero(bmap_tmp, 100);
+	bitmap_zero(bmap_res, 100);
 	bitmap_gather(bmap_tmp, bmap_scatter, sg_mask, nbits);
 	bitmap_scatter(bmap_res, bmap_tmp, sg_mask, nbits);
 	expect_eq_bitmap(bmap_scatter, bmap_res, 100);
-- 
2.54.0