selftests: kvm: fix get_run_delay() ignoring fscanf() return warn

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>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

diff --git a/tools/testing/selftests/kvm/include/test_util.h b/tools/testing/selftests/kvm/include/test_util.h
index c7409b9..451fed5 100644 (file)
--- 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 f80dd38..a9107bf 100644 (file)
--- 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 51fe95a..2172d65 100644 (file)
--- 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];