[LTP] [PATCH] fcntl37: test posix lock across execve

[Cyril Hrubis]

Hi!
> diff --git a/testcases/kernel/syscalls/fcntl/Makefile b/testcases/kernel/syscalls/fcntl/Makefile
> index ae37214..7a06aa7 100644
> --- a/testcases/kernel/syscalls/fcntl/Makefile
> +++ b/testcases/kernel/syscalls/fcntl/Makefile
> @@ -27,6 +27,9 @@ fcntl34_64: LDLIBS += -lpthread
>  fcntl36: LDLIBS += -lpthread
>  fcntl36_64: LDLIBS += -lpthread
>  
> +fcntl37: LDLIBS += -lpthread
> +fcntl37_64: LDLIBS += -lpthread

This is wrong, we should use CFLAGS += -pthread instead, also the rest
of the Makefile should be fixed as well.

>  include $(top_srcdir)/include/mk/testcases.mk
>  include $(abs_srcdir)/../utils/newer_64.mk

...

> +#include "lapi/fcntl.h"
> +#include "tst_safe_pthread.h"
> +#include "tst_test.h"
> +
> +static const char fname[] = "tst_lock_execve";
> +static const char flag_fname[] = "/tmp/execved";
                                       ^
				     You must not create files in random
				     places. Once you set the
				     .needs_tmpdir in the test structure
				     the test is executed with unique temporary
				     directory as working directory so
				     all you need to do for temporary
				     files is to work with relative filenames.

> +static void cleanup(void);
> +
> +static void *thread_fn(void *arg)
> +{
> +	int fd = *(int *)arg;
                   ^
		   This is broken, you have to use intptr_t

> +	tst_res(TINFO, "Thread running. fd %d", fd);
> +	/* Just need to be alive when execve. */
> +	sleep(5);
> +	SAFE_CLOSE(fd);
> +	return NULL;
> +}
> +
> +static void checklock(int fd)
> +{
> +	pid_t pid = SAFE_FORK();
> +	if (pid == 0) {
> +		struct flock flck = {
> +			.l_type = F_WRLCK,
> +			.l_whence = SEEK_SET,
> +			.l_start = 0,
> +			.l_len = 1,
> +		};
> +		SAFE_FCNTL(fd, F_GETLK, &flck);
> +		if (flck.l_type == F_UNLCK)
> +			tst_res(TFAIL, "Record lock gets lost after execve");
> +		else
> +			tst_res(TPASS, "Record lock survives execve");
> +		SAFE_CLOSE(fd);
> +		_exit(0);

Why _exit() ?

> +	}
> +	waitpid(pid, NULL, 0);

SAFE_WAITPID()

> +}

Also having the check in a separate function and calling it several
times makes it kind of hard for debugging. if one of the assertions
fails the error messages would be the same. Maybe we should pass a
string with describes assertion type to the function and use it
int the tst_res() messages.

> +static void test01(void)
> +{
> +	int fd, ret;
> +	struct stat stat_buf;
> +
> +	/*
> +	 * If tmp/tst_lock_execve exists, execve to run checklock.
> +	 */
> +	ret = stat(flag_fname, &stat_buf);
> +	if (ret == 0) {
> +		checklock(fd);
> +		cleanup();

You must not call the cleanup from the test. Cleanup function is called
from the test library.

> +		_exit(0);

Again why _exit() ?

> +	}

Don't do this.

You must not reexecute the testcase and put file flags into random
places. If you need execve() a test helper, you have to write simple
binary helper. See testcases/kernel/syscalls/creat/creat07_child.c

> +	/*
> +	 * If tmp/tst_lock_execve does not exist, initialize it.
> +	 */

Please no useless comments like this one.

> +	SAFE_OPEN(flag_fname, O_RDWR|O_CREAT, 0755);
> +	fd = SAFE_OPEN(fname, O_RDWR|O_CREAT, 0755);
> +	struct flock64 flck = {
> +		.l_type = F_WRLCK,
> +		.l_whence = SEEK_SET,
> +		.l_start  = 0,
> +		.l_len    = 1,
> +	};
> +	SAFE_FCNTL(fd, F_SETLK, &flck);
> +
> +	/*
> +	 * Creat thread and keep it running after placing posix
> +	 * write lock.
> +	 */

Please no useless comments.

> +	pthread_t th;
> +	SAFE_PTHREAD_CREATE(&th, NULL, thread_fn, (void *)&fd);
                                                    ^
						    Here as well, we
						    have to cast the fd
						    to intptr_t first.
> +	sleep(1);

Please no random sleeps() for thread synchronization, either use real
thread synchronization primitives or LTP checkpoint synchronization
library which is based on futexes.

See:
https://github.com/linux-test-project/ltp/wiki/Test-Writing-Guidelines#229-fork-and-parent-child-synchronization

> +	/*
> +	 * Clear CLOEXEC
> +	 */

Please no useless comments.

> +	int flags=SAFE_FCNTL(fd, F_GETFD);
> +	flags &= ~FD_CLOEXEC;
> +	SAFE_FCNTL(fd, F_SETFD, flags);
> +
> +	/*
> +	 * Get full path name of running programm then execve.
> +	 */

Please no useless comments.


> +	char prog_name[PATH_MAX];
> +	ret = readlink("/proc/self/exe", prog_name, PATH_MAX);
> +	char * const newargv[] = { prog_name, NULL, NULL };

This is far to complicated for no reason. The path to LTP test binaries
is in $PATH so you can execute any LTP binary just by it's name.
Absolute path is absolutely unneeded.

> +	tst_res(TINFO, "execve %s with %s locked", prog_name, fname);
> +	execve(prog_name, newargv, NULL);
> +	/*
> +	 * Failure info for debug
> +	 */

Please no useless comments.

> +	perror("execve ");

No perror() please. Any error messages should be printed via tst_res()
or tst_brk().

> +}
> +
> +static void cleanup(void)
> +{
> +	SAFE_UNLINK(flag_fname);
> +}
> +
> +static struct tst_test test = {
> +	.needs_tmpdir = 1,
> +	.forks_child = 1,
> +	.test_all = test01,
> +	.cleanup = cleanup,
> +};
> -- 
> 1.8.3.1
> 
> 
> -- 
> Mailing list info: https://lists.linux.it/listinfo/ltp

-- 
Cyril Hrubis
chrubis@suse.cz