[LTP] [PATCH/RFC] sem_post/8-1: improve "child blocked on semaphore" detection

[Cyril Hrubis]

Hi!
>  .../conformance/interfaces/sem_post/8-1.c          |  6 ++-
>  testcases/open_posix_testsuite/include/proc.h      | 61 ++++++++++++++++++++++
>  2 files changed, 65 insertions(+), 2 deletions(-)
>  create mode 100644 testcases/open_posix_testsuite/include/proc.h
> 
> diff --git a/testcases/open_posix_testsuite/conformance/interfaces/sem_post/8-1.c b/testcases/open_posix_testsuite/conformance/interfaces/sem_post/8-1.c
> index 08e94639acaf..d41a7e47ea91 100644
> --- a/testcases/open_posix_testsuite/conformance/interfaces/sem_post/8-1.c
> +++ b/testcases/open_posix_testsuite/conformance/interfaces/sem_post/8-1.c
> @@ -44,6 +44,7 @@
>  #include <sys/types.h>
>  #include <sys/wait.h>
>  #include <stdlib.h>
> +#include "proc.h"
>  
>  #define TEST "sem_post_8-1"
>  
> @@ -184,7 +185,8 @@ int main(void)
>  		usleep(100);
>  		sem_getvalue(sem_1, &val);
>  	} while (val != 1);
> -	usleep(100);
> +	tst_process_state_wait3(c_1, 'S', 2000);
> +	tst_process_state_wait3(c_2, 'S', 2000);
>  
>  	c_3 = fork();
>  	switch (c_3) {
> @@ -204,7 +206,7 @@ int main(void)
>  		usleep(100);
>  		sem_getvalue(sem_1, &val);
>  	} while (val != 0);
> -	usleep(100);
> +	tst_process_state_wait3(c_3, 'S', 2000);

So sem_1 semaphore is used just as a counter and we are fixing race
before the children decrement its value and lock on the second
semaphore, right?

The approach here seems reasonable, acked.

>  	/* Ok, let's release the lock */
>  	fprintf(stderr, "P: release lock\n");
> diff --git a/testcases/open_posix_testsuite/include/proc.h b/testcases/open_posix_testsuite/include/proc.h
> new file mode 100644
> index 000000000000..d58fb13549bd
> --- /dev/null
> +++ b/testcases/open_posix_testsuite/include/proc.h
> @@ -0,0 +1,61 @@
> +/*
> + * Copyright (c) 2017 Linux Test Project
> + *
> + * This program is free software;  you can redistribute it and/or modify
> + * it under the terms in version 2 of the GNU General Public License as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY;  without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
> + * the GNU General Public License for more details.
> + */
> +
> +#ifdef __linux__
> +# include <errno.h>
> +# include <string.h>
> +int tst_process_state_wait3(pid_t pid, const char state,
> +	unsigned long maxwait_ms)
> +{
> +	char proc_path[128], cur_state;
> +	int wait_step_ms = 10;
> +	unsigned long waited_ms = 0;
> +
> +	snprintf(proc_path, sizeof(proc_path), "/proc/%i/stat", pid);
> +
> +	for (;;) {
> +		FILE *f = fopen(proc_path, "r");
> +
> +		if (!f) {
> +			fprintf(stderr, "Failed to open '%s': %s\n",
> +				proc_path, strerror(errno));
> +			return 1;
> +		}
> +
> +		if (fscanf(f, "%*i %*s %c", &cur_state) != 1) {
> +			fclose(f);
> +			fprintf(stderr, "Failed to read '%s': %s\n",
> +				proc_path, strerror(errno));
> +			return 1;
> +		}
> +		fclose(f);
> +
> +		if (state == cur_state)
> +			return 0;
> +
> +		usleep(wait_step_ms * 1000);
> +		waited_ms += wait_step_ms;
> +
> +		if (waited_ms >= maxwait_ms) {
> +			fprintf(stderr, "Reached max wait time\n");
> +			return 1;
> +		}
> +	}
> +}
> +#else
> +int tst_process_state_wait3(pid_t pid, const char state,
> +	unsigned long maxwait_ms)
> +{
> +	usleep(maxwait_ms * 1000);

return 0; here?

We don't handle it anyway but missing return would produce a warning...

> +}
> +#endif
> -- 
> 1.8.3.1
> 
> 
> -- 
> Mailing list info: https://lists.linux.it/listinfo/ltp

-- 
Cyril Hrubis
chrubis@suse.cz