[PATCH] selftests/mm/uffd: initialize char variable to Null

[Ankit Khushwaha]

In "uffd-stress.c" & "uffd-unit-tests.c". address of char variable having
garbage value (uninitialized) is passed to 'write' syscall triggers
warning.

        uffd-stress.c:246:39: warning: variable 'c' is uninitialized when
        passed  as a const pointer argument here
        [-Wuninitialized-const-pointer]

        uffd-unit-tests.c:581:31: warning: variable 'c' is uninitialized
        when passed as a const pointer argument here
        [-Wuninitialized-const-pointer]

so the fix is to assign char variable to '\0' to prevent writing of
garbage value.

Signed-off-by: Ankit Khushwaha <ankitkhushwaha.li...@gmail.com>
---
this warning is raised with clang version 21.1.5 (Fedora 21.1.5-1.fc43).
---
 tools/testing/selftests/mm/uffd-stress.c     | 2 +-
 tools/testing/selftests/mm/uffd-unit-tests.c | 8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/mm/uffd-stress.c 
b/tools/testing/selftests/mm/uffd-stress.c
index b51c89e1cd1a..700fbaa18d44 100644
--- a/tools/testing/selftests/mm/uffd-stress.c
+++ b/tools/testing/selftests/mm/uffd-stress.c
@@ -241,7 +241,7 @@ static int stress(struct uffd_args *args)
                        return 1;

        for (cpu = 0; cpu < gopts->nr_parallel; cpu++) {
-               char c;
+               char c = '\0';
                if (bounces & BOUNCE_POLL) {
                        if (write(gopts->pipefd[cpu*2+1], &c, 1) != 1)
                                err("pipefd write error");
diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c 
b/tools/testing/selftests/mm/uffd-unit-tests.c
index f917b4c4c943..f4807242c5b2 100644
--- a/tools/testing/selftests/mm/uffd-unit-tests.c
+++ b/tools/testing/selftests/mm/uffd-unit-tests.c
@@ -543,7 +543,7 @@ static void uffd_minor_test_common(uffd_global_test_opts_t 
*gopts, bool test_col
 {
        unsigned long p;
        pthread_t uffd_mon;
-       char c;
+       char c = '\0';
        struct uffd_args args = { 0 };
        args.gopts = gopts;

@@ -759,7 +759,7 @@ static void uffd_sigbus_test_common(uffd_global_test_opts_t 
*gopts, bool wp)
        pthread_t uffd_mon;
        pid_t pid;
        int err;
-       char c;
+       char c = '\0';
        struct uffd_args args = { 0 };
        args.gopts = gopts;

@@ -819,7 +819,7 @@ static void uffd_events_test_common(uffd_global_test_opts_t 
*gopts, bool wp)
        pthread_t uffd_mon;
        pid_t pid;
        int err;
-       char c;
+       char c = '\0';
        struct uffd_args args = { 0 };
        args.gopts = gopts;

@@ -1125,7 +1125,7 @@ uffd_move_test_common(uffd_global_test_opts_t *gopts,
 {
        unsigned long nr;
        pthread_t uffd_mon;
-       char c;
+       char c = '\0';
        unsigned long long count;
        struct uffd_args args = { 0 };
        char *orig_area_src = NULL, *orig_area_dst = NULL;
--
2.52.0