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 <[email protected]> Acked-by: Paolo Bonzini <[email protected]> Signed-off-by: Shuah Khan <[email protected]>
blogic · Sep 16, 2021 · f5013d4 · f5013d4
1 parent 20175d5
commit f5013d4
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Showing 3 changed files with 5 additions and 2 deletions.
diff --git 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
@@ -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
@@ -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];