[PATCH v2 3/3] selftests/mm: fix ternary operator precedence in ksm_tests

[Sayali Patil]

The KSM selftest uses conditional expressions to skip accesses to
merge_across_nodes on systems without NUMA support. However, the
ternary operator is combined with logical OR without parentheses:

a || numa_available() ? 0 : b || c

Due to operator precedence rules, this is parsed as:

(a || numa_available()) ? 0 : (b || c)

instead of the intended:

a || (numa_available() ? 0 : b) || c

Add parentheses around the conditional expressions to ensure the
correct evaluation order.

Fixes: 9aa1af954db0 ("selftests: vm: check numa_available() before operating 
"merge_across_nodes" in ksm_tests")
Signed-off-by: Sayali Patil <saya...@linux.ibm.com>
---
 tools/testing/selftests/mm/ksm_tests.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/mm/ksm_tests.c 
b/tools/testing/selftests/mm/ksm_tests.c
index 2ebbb544c671..5fd7792a0d47 100644
--- a/tools/testing/selftests/mm/ksm_tests.c
+++ b/tools/testing/selftests/mm/ksm_tests.c
@@ -288,8 +288,8 @@ static bool assert_ksm_pages_count(long dupl_page_count)
 static int ksm_save_def(struct ksm_sysfs *ksm_sysfs)
 {
        if (ksm_read_sysfs(KSM_FP("max_page_sharing"), 
&ksm_sysfs->max_page_sharing) ||
-           numa_available() ? 0 :
-               ksm_read_sysfs(KSM_FP("merge_across_nodes"), 
&ksm_sysfs->merge_across_nodes) ||
+           (numa_available() ? 0 :
+               ksm_read_sysfs(KSM_FP("merge_across_nodes"), 
&ksm_sysfs->merge_across_nodes)) ||
            ksm_read_sysfs(KSM_FP("sleep_millisecs"), 
&ksm_sysfs->sleep_millisecs) ||
            ksm_read_sysfs(KSM_FP("pages_to_scan"), &ksm_sysfs->pages_to_scan) 
||
            ksm_read_sysfs(KSM_FP("run"), &ksm_sysfs->run) ||
@@ -304,8 +304,8 @@ static int ksm_save_def(struct ksm_sysfs *ksm_sysfs)
 static int ksm_restore(struct ksm_sysfs *ksm_sysfs)
 {
        if (ksm_write_sysfs(KSM_FP("max_page_sharing"), 
ksm_sysfs->max_page_sharing) ||
-           numa_available() ? 0 :
-               ksm_write_sysfs(KSM_FP("merge_across_nodes"), 
ksm_sysfs->merge_across_nodes) ||
+           (numa_available() ? 0 :
+               ksm_write_sysfs(KSM_FP("merge_across_nodes"), 
ksm_sysfs->merge_across_nodes)) ||
            ksm_write_sysfs(KSM_FP("pages_to_scan"), ksm_sysfs->pages_to_scan) 
||
            ksm_write_sysfs(KSM_FP("run"), ksm_sysfs->run) ||
            ksm_write_sysfs(KSM_FP("sleep_millisecs"), 
ksm_sysfs->sleep_millisecs) ||
@@ -846,8 +846,8 @@ int main(int argc, char *argv[])
 
        if (ksm_write_sysfs(KSM_FP("run"), 2) ||
            ksm_write_sysfs(KSM_FP("sleep_millisecs"), 0) ||
-           numa_available() ? 0 :
-               ksm_write_sysfs(KSM_FP("merge_across_nodes"), 1) ||
+           (numa_available() ? 0 :
+               ksm_write_sysfs(KSM_FP("merge_across_nodes"), 1)) ||
            ksm_write_sysfs(KSM_FP("pages_to_scan"), page_count))
                ksft_exit_fail_msg("Cannot set up KSM tunables\n");
 
-- 
2.52.0