PURPOSE of /tools/glibc/Regression/bz549813-dl-close-race-with-C-destructor
Description: Test for bz549813 (dl_close() race with C++ destructor)
Author: Petr Muller <pmuller@redhat.com>
Bug summary: dl_close() race with C++ destructor
Bugzilla link: https://bugzilla.redhat.com/show_bug.cgi?id=549813

Description:

This looks like a dup of

http://sources.redhat.com/bugzilla/show_bug.cgi?id=654


Create a pthread in the library init. In fini, cancel the pthread and then join. If the main thread does a dlclose(), the program hangs at pthread_join(). 
It is stuck in a futex. I tried the testcase from http://sources.redhat.com/bugzilla/show_bug.cgi?id=654 and that fails too. 

One thing that may be relevant is that if dlopen is called with RTLD_NODELETE, pthread_join will not hang.


main program->

#include <stdio.h> 
#include <dlfcn.h> 

int main(int argc, char *argv[]) {
	void *handle;

	handle =  dlopen("tiny.so",RTLD_NOW);
	if (handle) 
		printf("loaded shared library\n");
	else {
		printf("could not load shared library\n");
		return (-1);
	}	
	sleep(1);
	dlclose(handle);

}

the lib ->

#include <pthread.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <signal.h>
pthread_t t;


void *F(void *arg) {

	int old;
	if (pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, &old) == 0) {
		printf("> cancelability enabled.\n");
	}
	else {
		printf("> could not set cancelability\n");
		return (0);
	}

	sleep(2);
} /*end F */

int _init_rick (void) {

printf("in init\n");
    if (pthread_create(&t, NULL, (void *(*)(void *)) F, NULL) == 0) 
	printf("started thread\n");
else
	printf("could not start thread\n");

} /* end _init_rick */

int _fini_rick (void) {

	printf("in fini\n");

	printf("canceling thread\n");
	if (pthread_cancel(t) == 0)
		printf("canceled thread\n");
	else
		printf("could not cancel thread \n");
	
	printf("joining thread\n");
	if (pthread_join(t, NULL) == 0)
		printf("joined with thread\n");
	else
		printf("could not join with thread\n");


} /* end _fini_rick */
