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Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Nathan Chancellor , Nick Desaulniers , Bill Wendling , Justin Stitt , Shuah Khan , linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev Subject: Re: [PATCH] selftests/mm/uffd: initialize char variable to Null Message-ID: References: <20251126160830.52124-1-ankitkhushwaha.linux@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251126160830.52124-1-ankitkhushwaha.linux@gmail.com> X-Rspam-User: X-Rspamd-Queue-Id: 0FE35180009 X-Rspamd-Server: rspam11 X-Stat-Signature: s8cmphxichc5z5giiwq5ncuza6jr7s9c X-HE-Tag: 1764219991-4964 X-HE-Meta: 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 h6qnWhIW ViHjBwdMBkUNyYHJIXy930v4UMRO4yOSHI835lo6gI7aADm4z17OdvVOenE/vHxGx1Mt1oeG1wo4cMS5FePi5X7iBq3aDiSG2caLHVl3whPza2QjpKX824SaLURuARX8JvQ5cHckvVZ4I/Sy38cobt5i2YpfRghYIT+8lx6LLEBrx7keoqsbER5ub7iisq1womyFYPUTM/H5LgMbogqoYpyupheqoNj9yh3951Xudu+ZW3LdSULzA17NDN2Whxq/EnSeerqNgK9WFsDUUeDEpayxOQYTHIqusZlkUZ5U8qYb41i7gogomPT9AZjtQlvFso8yl+Wp/utn/09gLeXgJ1PgdliVLQe3DBdD1CL8ioiLA+a+UXDxYD5JfeQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Nov 26, 2025 at 09:38:30PM +0530, Ankit Khushwaha wrote: > 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/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 > -- Sincerely yours, Mike.