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Subject[PATCH 4/4] selftests: kvm: fix get_run_delay() ignoring fscanf() return warn
Date
Fix get_run_delay() to check fscanf() return value to get rid of the
following warning. When fscanf() fails return MIN_RUN_DELAY_NS from
get_run_delay(). Move MIN_RUN_DELAY_NS from steal_time.c to test_util.h
so get_run_delay() and steal_time.c can use it.

lib/test_util.c: In function ‘get_run_delay’:
lib/test_util.c:316:2: warning: ignoring return value of ‘fscanf’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
316 | fscanf(fp, "%ld %ld ", &val[0], &val[1]);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
---
tools/testing/selftests/kvm/include/test_util.h | 2 ++
tools/testing/selftests/kvm/lib/test_util.c | 4 +++-
tools/testing/selftests/kvm/steal_time.c | 1 -
3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/test_util.h b/tools/testing/selftests/kvm/include/test_util.h
index c7409b9b4e5b..451fed5ce8e7 100644
--- a/tools/testing/selftests/kvm/include/test_util.h
+++ b/tools/testing/selftests/kvm/include/test_util.h
@@ -95,6 +95,8 @@ struct vm_mem_backing_src_alias {
uint32_t flag;
};

+#define MIN_RUN_DELAY_NS 200000UL
+
bool thp_configured(void);
size_t get_trans_hugepagesz(void);
size_t get_def_hugetlb_pagesz(void);
diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
index f80dd38a38b2..a9107bfae402 100644
--- a/tools/testing/selftests/kvm/lib/test_util.c
+++ b/tools/testing/selftests/kvm/lib/test_util.c
@@ -313,7 +313,9 @@ long get_run_delay(void)

sprintf(path, "/proc/%ld/schedstat", syscall(SYS_gettid));
fp = fopen(path, "r");
- fscanf(fp, "%ld %ld ", &val[0], &val[1]);
+ /* Return MIN_RUN_DELAY_NS upon failure just to be safe */
+ if (fscanf(fp, "%ld %ld ", &val[0], &val[1]) < 2)
+ val[1] = MIN_RUN_DELAY_NS;
fclose(fp);

return val[1];
diff --git a/tools/testing/selftests/kvm/steal_time.c b/tools/testing/selftests/kvm/steal_time.c
index 51fe95a5c36a..2172d65b85e4 100644
--- a/tools/testing/selftests/kvm/steal_time.c
+++ b/tools/testing/selftests/kvm/steal_time.c
@@ -19,7 +19,6 @@

#define NR_VCPUS 4
#define ST_GPA_BASE (1 << 30)
-#define MIN_RUN_DELAY_NS 200000UL

static void *st_gva[NR_VCPUS];
static uint64_t guest_stolen_time[NR_VCPUS];
--
2.30.2
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