Re: PR/53998 CVS commit: src/sys/kern

[BERTRAND Joël <joel.bertrand%systella.fr@localhost>]

The following reply was made to PR kern/53998; it has been noted by GNATS.

From: =?UTF-8?Q?BERTRAND_Jo=c3=abl?= <joel.bertrand%systella.fr@localhost>
To: gnats-bugs%NetBSD.org@localhost, kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
        netbsd-bugs%netbsd.org@localhost
Cc: 
Subject: Re: PR/53998 CVS commit: src/sys/kern
Date: Thu, 28 Feb 2019 23:32:01 +0100

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 	Hello,
 
 	In attachement a quick and dirty program that shows sem_init() bugs. If
 I remove fork() in child thread, sem_init() runs fine.
 
 	Best regards,
 
 	JB
 
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 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <stdbool.h>
 #include <semaphore.h>
 #include <pthread.h>
 #include <string.h>
 
 #define NUMBER_OF_THREADS	8
 
 typedef struct
 {
 	pthread_t		tid;
 	volatile bool	active;
 	long long		i;
 	sem_t			s;
 } thread_arg_t;
 
 thread_arg_t targ[NUMBER_OF_THREADS];
 
 void *
 thread(void *arg)
 {
 	char			**arguments;
 
 	pid_t			pid;
 	thread_arg_t	*ta = arg;
 
 	if (sem_init(&(ta->s), 0, 0) != 0)
 	{
 		perror("sem_init()");
 		_exit(EXIT_FAILURE);
 	}
 
 	pid = fork();
 
 	if (pid < 0)
 	{
 		perror("fork()");
 		_exit(EXIT_FAILURE);
 	}
 	else if (pid == 0)
 	{
 		// Child
 
 		if ((arguments = malloc(3 * sizeof(char *))) == NULL)
 		{
 			perror("malloc()");
 			_exit(EXIT_FAILURE);
 		}
 
 		if ((arguments[0] = malloc(5 * sizeof(char *))) == NULL)
 		{
 			perror("malloc(0)");
 			_exit(EXIT_FAILURE);
 		}
 
 		if ((arguments[1] = malloc(40 * sizeof(char *))) == NULL)
 		{
 			perror("malloc(1)");
 			_exit(EXIT_FAILURE);
 		}
 
 		strcpy(arguments[0], "echo");
 		sprintf(arguments[1], "< %lld >", ta->i);
 		arguments[2] = NULL;
 
 		execvp(arguments[0], arguments);
 		perror("execvp()");
 		_exit(EXIT_FAILURE);
 	}
 
 	if (sem_destroy(&(ta->s)) != 0)
 	{
 		perror("sem_destroy()");
 		_exit(EXIT_FAILURE);
 	}
 
 	ta->active = false;
 	pthread_exit(NULL);
 }
 
 int
 main()
 {
 	int			i;
 	long long	nt;
 
 	for(nt = 0;;)
 	{
 		for(i = 0; i < NUMBER_OF_THREADS; i++)
 		{
 			if (targ[i].active == false)
 			{
 				break;
 			}
 		}
 
 		if (i < NUMBER_OF_THREADS)
 		{
 			printf("Free slot : %d (%lld threads)\n", i, ++nt);
 			targ[i].active = true;
 			targ[i].i = nt;
 
 			if (pthread_create(&(targ[i].tid), NULL, thread, &(targ[i])) != 0)
 			{
 				perror("pthread_create()");
 				exit(EXIT_FAILURE);
 			}
 
 			if (pthread_detach(targ[i].tid) != 0)
 			{
 				perror("pthread_detach()");
 				exit(EXIT_FAILURE);
 			}
 		}
 		else
 		{
 			usleep(1000);
 		}
 	}
 
 	exit(EXIT_SUCCESS);
 }
 
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