[PATCH v2] raid6/test/test.c: bug fix: Specify aligned(alignment) attributes to the char arrays

From: Gayatri Kammela
Date: Mon Sep 26 2016 - 17:41:46 EST

Specifying the aligned attributes to the char data[NDISKS][PAGE_SIZE],
char recovi[PAGE_SIZE] and char recovi[PAGE_SIZE] arrays, so that all
malloc memory is page boundary aligned.

Without these alignment attributes, the test causes a segfault in
userspace when the NDISKS are changed to 4 from 16.

The RAID stripes will be page aligned anyway, so we want to test what
the kernel actually will execute.

Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
Signed-off-by: Gayatri Kammela <gayatri.kammela@xxxxxxxxx>
Reviewed-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
lib/raid6/test/test.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/lib/raid6/test/test.c b/lib/raid6/test/test.c
index 3bebbabdb510..b07f4d8e6b03 100644
--- a/lib/raid6/test/test.c
+++ b/lib/raid6/test/test.c
@@ -21,12 +21,13 @@

#define NDISKS 16 /* Including P and Q */

-const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
+const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(PAGE_SIZE)));
struct raid6_calls raid6_call;

char *dataptrs[NDISKS];
-char data[NDISKS][PAGE_SIZE];
-char recovi[PAGE_SIZE], recovj[PAGE_SIZE];
+char data[NDISKS][PAGE_SIZE] __attribute__((aligned(PAGE_SIZE)));
+char recovi[PAGE_SIZE] __attribute__((aligned(PAGE_SIZE)));
+char recovj[PAGE_SIZE] __attribute__((aligned(PAGE_SIZE)));

static void makedata(int start, int stop)