Patch "selftests: kvm: fix get_run_delay() ignoring fscanf() return warn" has been added to the 5.14-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

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

to the 5.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     selftests-kvm-fix-get_run_delay-ignoring-fscanf-retu.patch
and it can be found in the queue-5.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit a22cb3b883e93537473c34f9f0cee00b8cb210fd
Author: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
Date:   Wed Sep 15 15:28:09 2021 -0600

    selftests: kvm: fix get_run_delay() ignoring fscanf() return warn
    
    [ Upstream commit f5013d412a43662b63f3d5f3a804d63213acd471 ]
    
    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@xxxxxxxxxxxxxxxxxxx>
    Acked-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
    Signed-off-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

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];