linux-kernel - [PATCH RESEND 2/3] lib/test_string: avoid masking memset16/32/64 failures

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Date:   Mon, 6 May 2019 12:47:07 +0000
From:   Peter Rosin <peda@...ntia.se>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Peter Rosin <peda@...ntia.se>,
        Matthew Wilcox <willy@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH RESEND 2/3] lib/test_string: avoid masking memset16/32/64
 failures

If a memsetXX implementation is completely broken and fails in the first
iteration, when i, j, and k are all zero, the failure is masked as zero
is returned. Failing in the first iteration is perhaps the most likely
failure, so this makes the tests pretty much useless. Avoid the situation
by always setting a random unused bit in the result on failure.

Fixes: 03270c13c5ff ("lib/string.c: add testcases for memset16/32/64")
Signed-off-by: Peter Rosin <peda@...ntia.se>
---
 lib/test_string.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/lib/test_string.c b/lib/test_string.c
index 0fcdb82dca86..98a787e7a1fd 100644
--- a/lib/test_string.c
+++ b/lib/test_string.c
@@ -35,7 +35,7 @@ static __init int memset16_selftest(void)
 fail:
 	kfree(p);
 	if (i < 256)
-		return (i << 24) | (j << 16) | k;
+		return (i << 24) | (j << 16) | k | 0x8000;
 	return 0;
 }
 
@@ -71,7 +71,7 @@ static __init int memset32_selftest(void)
 fail:
 	kfree(p);
 	if (i < 256)
-		return (i << 24) | (j << 16) | k;
+		return (i << 24) | (j << 16) | k | 0x8000;
 	return 0;
 }
 
@@ -107,7 +107,7 @@ static __init int memset64_selftest(void)
 fail:
 	kfree(p);
 	if (i < 256)
-		return (i << 24) | (j << 16) | k;
+		return (i << 24) | (j << 16) | k | 0x8000;
 	return 0;
 }
 
-- 
2.11.0