From b1e34412998d628dfa8ba3da042bb60dee232b6c Mon Sep 17 00:00:00 2001 From: Alexey Dobriyan Date: Tue, 19 Aug 2025 21:19:17 +0300 Subject: proc: test lseek on /proc/net/dev This line in tools/testing/selftests/proc/read.c was added to catch oopses, not to verify lseek correctness: (void)lseek(fd, 0, SEEK_SET); Oh, well. Prevent more embarassement with simple test. Link: https://lkml.kernel.org/r/aKTCfMuRXOpjBXxI@p183 Signed-off-by: Alexey Dobriyan Signed-off-by: Andrew Morton --- tools/testing/selftests/proc/.gitignore | 1 + tools/testing/selftests/proc/Makefile | 1 + tools/testing/selftests/proc/proc-net-dev-lseek.c | 68 +++++++++++++++++++++++ 3 files changed, 70 insertions(+) create mode 100644 tools/testing/selftests/proc/proc-net-dev-lseek.c (limited to 'tools/testing/selftests') diff --git a/tools/testing/selftests/proc/.gitignore b/tools/testing/selftests/proc/.gitignore index 19bb333e2485..243f4537a670 100644 --- a/tools/testing/selftests/proc/.gitignore +++ b/tools/testing/selftests/proc/.gitignore @@ -7,6 +7,7 @@ /proc-loadavg-001 /proc-maps-race /proc-multiple-procfs +/proc-net-dev-lseek /proc-empty-vm /proc-pid-vm /proc-self-map-files-001 diff --git a/tools/testing/selftests/proc/Makefile b/tools/testing/selftests/proc/Makefile index 50aba102201a..2a9547630115 100644 --- a/tools/testing/selftests/proc/Makefile +++ b/tools/testing/selftests/proc/Makefile @@ -10,6 +10,7 @@ TEST_GEN_PROGS += fd-003-kthread TEST_GEN_PROGS += proc-2-is-kthread TEST_GEN_PROGS += proc-loadavg-001 TEST_GEN_PROGS += proc-maps-race +TEST_GEN_PROGS += proc-net-dev-lseek TEST_GEN_PROGS += proc-empty-vm TEST_GEN_PROGS += proc-pid-vm TEST_GEN_PROGS += proc-self-map-files-001 diff --git a/tools/testing/selftests/proc/proc-net-dev-lseek.c b/tools/testing/selftests/proc/proc-net-dev-lseek.c new file mode 100644 index 000000000000..742a3e804451 --- /dev/null +++ b/tools/testing/selftests/proc/proc-net-dev-lseek.c @@ -0,0 +1,68 @@ +/* + * Copyright (c) 2025 Alexey Dobriyan + * + * Permission to use, copy, modify, and distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ +#undef _GNU_SOURCE +#define _GNU_SOURCE +#undef NDEBUG +#include +#include +#include +#include +#include +#include +/* + * Test that lseek("/proc/net/dev/", 0, SEEK_SET) + * a) works, + * b) does what you think it does. + */ +int main(void) +{ + /* /proc/net/dev output is deterministic in fresh netns only. */ + if (unshare(CLONE_NEWNET) == -1) { + if (errno == ENOSYS || errno == EPERM) { + return 4; + } + return 1; + } + + const int fd = open("/proc/net/dev", O_RDONLY); + assert(fd >= 0); + + char buf1[4096]; + const ssize_t rv1 = read(fd, buf1, sizeof(buf1)); + /* + * Not "<=", this file can't be empty: + * there is header, "lo" interface with some zeroes. + */ + assert(0 < rv1); + assert(rv1 <= sizeof(buf1)); + + /* Believe it or not, this line broke one day. */ + assert(lseek(fd, 0, SEEK_SET) == 0); + + char buf2[4096]; + const ssize_t rv2 = read(fd, buf2, sizeof(buf2)); + /* Not "<=", see above. */ + assert(0 < rv2); + assert(rv2 <= sizeof(buf2)); + + /* Test that lseek rewinds to the beginning of the file. */ + assert(rv1 == rv2); + assert(memcmp(buf1, buf2, rv1) == 0); + + /* Contents of the file is not validated: this test is about lseek(). */ + + return 0; +} -- cgit v1.2.3 From 17bdc64c0d419b78bb400c221d36eaa391d16b3a Mon Sep 17 00:00:00 2001 From: Bala-Vignesh-Reddy Date: Wed, 20 Aug 2025 23:26:10 +0530 Subject: selftests: proc: mark vsyscall strings maybe-unused The str_vsyscall_* constants in proc-pid-vm.c triggers -Wunused-const-variable warnings with gcc-13.32 and clang 18.1. Define and apply __maybe_unused locally to suppress the warnings. No functional change Fixes compiler warning: warning: `str_vsyscall_*' defined but not used[-Wunused-const-variable] Link: https://lkml.kernel.org/r/20250820175610.83014-1-reddybalavignesh9979@gmail.com Signed-off-by: Bala-Vignesh-Reddy Cc: Shuah Khan Cc: Suren Baghdasaryan Signed-off-by: Andrew Morton --- tools/testing/selftests/proc/proc-pid-vm.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) (limited to 'tools/testing/selftests') diff --git a/tools/testing/selftests/proc/proc-pid-vm.c b/tools/testing/selftests/proc/proc-pid-vm.c index d04685771952..978cbcb3eb11 100644 --- a/tools/testing/selftests/proc/proc-pid-vm.c +++ b/tools/testing/selftests/proc/proc-pid-vm.c @@ -47,6 +47,10 @@ #include #include +#ifndef __maybe_unused +#define __maybe_unused __attribute__((__unused__)) +#endif + #include "../kselftest.h" static inline long sys_execveat(int dirfd, const char *pathname, char **argv, char **envp, int flags) @@ -218,12 +222,12 @@ static int make_exe(const uint8_t *payload, size_t len) * 2: vsyscall VMA is r-xp vsyscall=emulate */ static volatile int g_vsyscall; -static const char *str_vsyscall; +static const char *str_vsyscall __maybe_unused; -static const char str_vsyscall_0[] = ""; -static const char str_vsyscall_1[] = +static const char str_vsyscall_0[] __maybe_unused = ""; +static const char str_vsyscall_1[] __maybe_unused = "ffffffffff600000-ffffffffff601000 --xp 00000000 00:00 0 [vsyscall]\n"; -static const char str_vsyscall_2[] = +static const char str_vsyscall_2[] __maybe_unused = "ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]\n"; #ifdef __x86_64__ -- cgit v1.2.3