Re: BUG: NTPL: waitpid() doesn't return?

From: bert hubert (ahu_at_ds9a.nl)
Date: 01/31/04

  • Next message: john moser: "ACPI -- Workaround for broken DSDT" 
    Date:	Sat, 31 Jan 2004 20:19:23 +0100
To: Matthias Urlichs <smurf@smurf.noris.de>

    [Added Ingo & NPTL list]

    [Matthias reports that threads forking multiple programs and running waitpid
     on them has problems]

    On Sat, Jan 31, 2004 at 07:15:19PM +0100, Matthias Urlichs wrote:

    > > If they do not wait for a specific pid, the kernel is right. The kernel has
    > > no way of knowing which process a specific waitpid is waiting for otherwise!
    > >
    > Please check my original mail again. The thread _is_ waiting for a
    > specific pid.

    I can't reproduce this with 2.6.1, can you check if this works as intended
    on your system? Should output:

    Thread 0 Launched pid 10967
    Thread 1 Launched pid 10971
    Thread 1 waitpid for 10971 returned for 10971, status: 1
    Thread 0 waitpid for 10967 returned for 10967, status: 3

    This is with NPTL 0.60 (Debian Unstable).

    ./sleep program:

    #!/bin/sh
    sleep $1
    exit $1

    testcase.c:

    #include <stdio.h>
    #include <sys/types.h>
    #include <sys/wait.h>
    #include <unistd.h>
    #include <pthread.h>
    #include <stdlib.h>

    void unixDie(const char* what)
    {
      perror(what);
      exit(1);
    }
    int s_counter;
    void *func(void *p)
    {
      pid_t pid;
      int status;
      int counter=s_counter++;

      pid=fork();
      if(pid<0)
        unixDie("doing fork");
      if(!pid) {
        char *arguments[]={"./sleep","",0};
        char str[10];
        sprintf(str,"%d",(int)p);
        arguments[1]=str;

        if(execve(arguments[0],arguments,0))
          unixDie("doing execve");
      }
      if(pid) {
        pid_t ret;
        printf("Thread %d Launched pid %d\n", counter, pid);
        ret=waitpid(pid, &status, 0);
        if(ret<0)
          unixDie("waitpid");

        printf("Thread %d waitpid for %d returned for %d, status: %d\n",counter, pid, ret, WEXITSTATUS(status));
      }

      return 0;
    }

    int main(int argc, char **argv)
    {
      pthread_t t1, t2;
      pthread_create(&t1, 0, func,(void*)3);
      sleep(1);
      pthread_create(&t2, 0, func,(void*)1);

      pthread_join(t2,0);
      pthread_join(t1,0);
      return 0;
    } 

    -- 
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