The following commit has been merged into the timers/urgent branch of tip:

Commit-ID: f7d5bcd35d427daac7e206b1073ca14f5db85c27 Gitweb: https://git.kernel.org/tip/f7d5bcd35d427daac7e206b1073ca14f5db85c27 Author: Nathan Chancellor nathan@kernel.org AuthorDate: Thu, 11 Apr 2024 11:45:40 -07:00 Committer: Thomas Gleixner tglx@linutronix.de CommitterDate: Fri, 12 Apr 2024 14:11:15 +02:00

selftests: kselftest: Mark functions that unconditionally call exit() as __noreturn

After commit 6d029c25b71f ("selftests/timers/posix_timers: Reimplement check_timer_distribution()"), clang warns:

tools/testing/selftests/timers/../kselftest.h:398:6: warning: variable 'major' is used uninitialized whenever '||' condition is true [-Wsometimes-uninitialized] 398 | if (uname(&info) || sscanf(info.release, "%u.%u.", &major, &minor) != 2) | ^~~~~~~~~~~~ tools/testing/selftests/timers/../kselftest.h:401:9: note: uninitialized use occurs here 401 | return major > min_major || (major == min_major && minor >= min_minor); | ^~~~~ tools/testing/selftests/timers/../kselftest.h:398:6: note: remove the '||' if its condition is always false 398 | if (uname(&info) || sscanf(info.release, "%u.%u.", &major, &minor) != 2) | ^~~~~~~~~~~~~~~ tools/testing/selftests/timers/../kselftest.h:395:20: note: initialize the variable 'major' to silence this warning 395 | unsigned int major, minor; | ^ | = 0

This is a false positive because if uname() fails, ksft_exit_fail_msg() will be called, which unconditionally calls exit(), a noreturn function. However, clang does not know that ksft_exit_fail_msg() will call exit() at the point in the pipeline that the warning is emitted because inlining has not occurred, so it assumes control flow will resume normally after ksft_exit_fail_msg() is called.

Make it clear to clang that all of the functions that call exit() unconditionally in kselftest.h are noreturn transitively by marking them explicitly with '__attribute__((__noreturn__))', which clears up the warning above and any future warnings that may appear for the same reason.

Fixes: 6d029c25b71f ("selftests/timers/posix_timers: Reimplement check_timer_distribution()") Reported-by: John Stultz jstultz@google.com Signed-off-by: Nathan Chancellor nathan@kernel.org Signed-off-by: Thomas Gleixner tglx@linutronix.de Acked-by: Shuah Khan skhan@linuxfoundation.org Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20240411-mark-kselftest-exit-funcs-noreturn-v1-1-b... Closes: https://lore.kernel.org/all/20240410232637.4135564-2-jstultz@google.com/ --- tools/testing/selftests/kselftest.h | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/kselftest.h b/tools/testing/selftests/kselftest.h index 973b18e..0591974 100644 --- a/tools/testing/selftests/kselftest.h +++ b/tools/testing/selftests/kselftest.h @@ -80,6 +80,9 @@ #define KSFT_XPASS 3 #define KSFT_SKIP 4

+#ifndef __noreturn +#define __noreturn __attribute__((__noreturn__)) +#endif #define __printf(a, b) __attribute__((format(printf, a, b)))

/* counters */ @@ -300,13 +303,13 @@ void ksft_test_result_code(int exit_code, const char *test_name, va_end(args); }

-static inline int ksft_exit_pass(void) +static inline __noreturn int ksft_exit_pass(void) { ksft_print_cnts(); exit(KSFT_PASS); }

-static inline int ksft_exit_fail(void) +static inline __noreturn int ksft_exit_fail(void) { ksft_print_cnts(); exit(KSFT_FAIL); @@ -333,7 +336,7 @@ static inline int ksft_exit_fail(void) ksft_cnt.ksft_xfail + \ ksft_cnt.ksft_xskip)

-static inline __printf(1, 2) int ksft_exit_fail_msg(const char *msg, ...) +static inline __noreturn __printf(1, 2) int ksft_exit_fail_msg(const char *msg, ...) { int saved_errno = errno; va_list args; @@ -348,19 +351,19 @@ static inline __printf(1, 2) int ksft_exit_fail_msg(const char *msg, ...) exit(KSFT_FAIL); }

-static inline int ksft_exit_xfail(void) +static inline __noreturn int ksft_exit_xfail(void) { ksft_print_cnts(); exit(KSFT_XFAIL); }

-static inline int ksft_exit_xpass(void) +static inline __noreturn int ksft_exit_xpass(void) { ksft_print_cnts(); exit(KSFT_XPASS); }

-static inline __printf(1, 2) int ksft_exit_skip(const char *msg, ...) +static inline __noreturn __printf(1, 2) int ksft_exit_skip(const char *msg, ...) { int saved_errno = errno; va_list args;