svn commit: r218967 - head/sys/kern

[Kostik Belousov]

On Wed, Feb 23, 2011 at 12:56:25PM +0000, John Baldwin wrote:
> Author: jhb
> Date: Wed Feb 23 12:56:25 2011
> New Revision: 218967
> URL: http://svn.freebsd.org/changeset/base/218967
> 
> Log:
>   Fix off-by-one error in check against max_threads_per_proc.
>   
>   Submitted by:	arundel
>   MFC after:	1 week
> 
> Modified:
>   head/sys/kern/kern_thr.c
> 
> Modified: head/sys/kern/kern_thr.c
> ==============================================================================
> --- head/sys/kern/kern_thr.c	Wed Feb 23 10:28:37 2011	(r218966)
> +++ head/sys/kern/kern_thr.c	Wed Feb 23 12:56:25 2011	(r218967)
> @@ -153,7 +153,7 @@ create_thread(struct thread *td, mcontex
>  	p = td->td_proc;
>  
>  	/* Have race condition but it is cheap. */
> -	if (p->p_numthreads >= max_threads_per_proc) {
> +	if (p->p_numthreads > max_threads_per_proc) {
>  		++max_threads_hits;
>  		return (EPROCLIM);
>  	}

I do not think there was off by one error. The create_thread() function
is called to create new thread, and before the process thread counter
is incremented in thread_link(). The old test tried to not allow more
then max_threads_per_proc threads in a process, now it allows to
create max_threads_per_proc.

My guess is that the reference to mentioned pthread_vfork_test failed
because reporter set kern.threads.max_threads_per_proc to 100. The
test actually tries to create 101 threads, 1 main + 100 new.
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