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Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Nathan Chancellor , Nick Desaulniers , Bill Wendling , Justin Stitt Cc: Shuah Khan , linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, Ankit Khushwaha Subject: [PATCH] selftests/mm/uffd: initialize char variable to Null Date: Wed, 26 Nov 2025 21:38:30 +0530 Message-ID: <20251126160830.52124-1-ankitkhushwaha.linux@gmail.com> X-Mailer: git-send-email 2.52.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 Reviewed-by: Mike Rapoport (Microsoft) --- 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/selft= ests/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 =3D 0; cpu < gopts->nr_parallel; cpu++) { - char c; + char c =3D '\0'; if (bounces & BOUNCE_POLL) { if (write(gopts->pipefd[cpu*2+1], &c, 1) !=3D 1) err("pipefd write error"); diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/s= elftests/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_opt= s_t *gopts, bool test_col { unsigned long p; pthread_t uffd_mon; - char c; + char c =3D '\0'; struct uffd_args args =3D { 0 }; args.gopts =3D gopts; @@ -759,7 +759,7 @@ static void uffd_sigbus_test_common(uffd_global_test_op= ts_t *gopts, bool wp) pthread_t uffd_mon; pid_t pid; int err; - char c; + char c =3D '\0'; struct uffd_args args =3D { 0 }; args.gopts =3D gopts; @@ -819,7 +819,7 @@ static void uffd_events_test_common(uffd_global_test_op= ts_t *gopts, bool wp) pthread_t uffd_mon; pid_t pid; int err; - char c; + char c =3D '\0'; struct uffd_args args =3D { 0 }; args.gopts =3D 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 =3D '\0'; unsigned long long count; struct uffd_args args =3D { 0 }; char *orig_area_src =3D NULL, *orig_area_dst =3D NULL; -- 2.52.0