i386/79772: Setting thread stacksize to PTHREAD_STACK_MIN disables thread creation

[Bill Middleton]

>Number:         79772
>Category:       i386
>Synopsis:       Setting thread stacksize to PTHREAD_STACK_MIN disables thread creation
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-i386
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sun Apr 10 23:50:21 GMT 2005
>Closed-Date:
>Last-Modified:
>Originator:     Bill Middleton
>Release:        6.0-CURRENT
>Organization:
>Environment:
FreeBSD myhostname.com 6.0-CURRENT FreeBSD 6.0-CURRENT #0: Wed Apr  6 02:41:00 CEST 2005     flashdict at gmail.com:/u2/freebsd/src/sys/i386/compile/MYKERNEL  i386

>Description:
Setting stacksize to PTHREAD_STACK_MIN disables new thread creation with EAGAIN and strerror: Resource temporarily unavailable

This when linked against libthr or libpthread. libc_r works ok.
>How-To-Repeat:
Compile the following C program and link against each of the three libs.

void thread_main (void *arg)
{
        sleep (10);
}

int main () {
        static pthread_t t1,t2;
        static pthread_attr_t attr;
        int ret;
        size_t mysize;
        ret = pthread_attr_init (&attr);
        ret = pthread_attr_getstacksize (&attr, &mysize);
        printf("Current stacksize is %d\n",mysize);
        printf("Starting a new thread\n");
        pthread_create (&t1, &attr, thread_main, NULL);
        if(ret == 0)
                printf("Thread created ok\n");
        printf("Setting stacksize to PTHREAD_STACK_MIN: %d\n",PTHREAD_STACK_MIN);
        ret = pthread_attr_setstacksize (&attr, PTHREAD_STACK_MIN);
        if(ret == 0)
                printf("Stacksize changed ok\n");
        else
                printf("Couldn't set stacksize: %s",strerror (ret));
        ret = pthread_attr_getstacksize (&attr, &mysize);
        printf("New stacksize is %d\n",mysize);
        printf("Starting another new thread\n");
        ret = pthread_create (&t2, &attr, thread_main, NULL);
        if(ret == 0)
                printf("Thread created ok\n");
        else
                printf("Couldn't create thread: %s\n",strerror (ret));
}

>Fix:
      Heh.  I wish.
>Release-Note:
>Audit-Trail:
>Unformatted: