[PATCH v5] lib/eal: fix segfaults in exiting

[Zeng, ZhichaoX]

Hi Stephen,

> >
> > +static void mark_forked(void)
> > +{
> > +	is_forked++;
> > +}
> > +
> 
> This will end up counting application threads as well.
> 

I think it would be counted in the child process when 'fork()' is called,
and in the parent process, it would be zero.

> Also, it would need to be atomic.
> 

Thanks for your advice.

> >  /* Launch threads, called at application init(). */  int
> > rte_eal_init(int argc, char **argv) @@ -1324,6 +1331,8 @@
> > rte_eal_init(int argc, char **argv)
> >
> >  	eal_mcfg_complete();
> >
> > +	pthread_atfork(NULL, NULL, mark_forked);
> > +
> >  	return fctret;
> >  }
> 
> >  int
> >  rte_eal_cleanup(void)
> >  {
> > +	if (is_forked)
> > +		return 0;
> > +
> 
> rte_eal_cleanup is supposed to be called only once by application.

Yes. But in some case(e.g. debug_autotest of dpdk-test), it would fork
a child process to test 'rte_exit()', then it would call 'rte_eal_cleanup()'.
So 'is_forked' is introduced to avoid this situation.

Regards
Zhichao