The following reply was made to PR kern/32962; it has been noted by GNATS.

From: Andrew Doran <ad@netbsd.org>
To: matthew green <mrg@eterna.com.au>
Cc: yamt@netbsd.org, gnats-bugs@NetBSD.org
Subject: Re: PR/32962
Date: Thu, 2 Nov 2006 00:44:14 +0000

 The earlier message I sent doesn't seem to have made it into gnats,
 trying again.
 
 Andrew
 
 Index: kern/kern_lwp.c
 ===================================================================
 RCS file: /cvsroot/src/sys/kern/kern_lwp.c,v
 retrieving revision 1.48
 diff -u -r1.48 kern_lwp.c
 --- kern/kern_lwp.c	1 Nov 2006 10:17:58 -0000	1.48
 +++ kern/kern_lwp.c	1 Nov 2006 19:06:26 -0000
 @@ -661,8 +661,8 @@
  		l->l_stat = LSZOMB;
  		p = l->l_proc;
  		p->p_nzlwps++;
 -		KERNEL_UNLOCK();
  		wakeup(&p->p_nlwps);
 +		KERNEL_UNLOCK();
  	}
  }
  
 Index: kern/kern_sig.c
 ===================================================================
 RCS file: /cvsroot/src/sys/kern/kern_sig.c,v
 retrieving revision 1.235
 diff -u -r1.235 kern_sig.c
 --- kern/kern_sig.c	1 Nov 2006 10:17:58 -0000	1.235
 +++ kern/kern_sig.c	1 Nov 2006 19:06:28 -0000
 @@ -1494,6 +1494,8 @@
  	if (l->l_flag & L_SA && l->l_savp->savp_lwp != l)
  		return 0;
  
 +	KERNEL_PROC_LOCK(l);
 +
  	if (p->p_stat == SSTOP) {
  		/*
  		 * The process is stopped/stopping. Stop ourselves now that
 @@ -1514,6 +1516,7 @@
  		signum = firstsig(&ss);
  		if (signum == 0) {		 	/* no signal to send */
  			p->p_sigctx.ps_sigcheck = 0;
 +			KERNEL_PROC_UNLOCK(l);
  			return (0);
  		}
  							/* take the signal! */
 @@ -1655,6 +1658,7 @@
  						/* leave the signal for later */
  	sigaddset(&p->p_sigctx.ps_siglist, signum);
  	CHECKSIGS(p);
 +	KERNEL_PROC_UNLOCK(l);
  	return (signum);
  }
  
 Index: kern/kern_synch.c
 ===================================================================
 RCS file: /cvsroot/src/sys/kern/kern_synch.c,v
 retrieving revision 1.171
 diff -u -r1.171 kern_synch.c
 --- kern/kern_synch.c	1 Nov 2006 10:17:58 -0000	1.171
 +++ kern/kern_synch.c	1 Nov 2006 19:06:29 -0000
 @@ -112,6 +112,14 @@
  int	lbolt;			/* once a second sleep address */
  int	rrticks;		/* number of hardclock ticks per roundrobin() */
  
 +#if defined(MULTIPROCESSOR) || defined(LOCKDEBUG)
 +#define	XXX_SCHED_LOCK		simple_lock(&sched_lock)
 +#define	XXX_SCHED_UNLOCK	simple_unlock(&sched_lock)
 +#else
 +#define	XXX_SCHED_LOCK		/* nothing */
 +#define	XXX_SCHED_UNLOCK	/* nothing */
 +#endif
 +
  /*
   * Sleep queues.
   *
 @@ -535,22 +543,22 @@
  	 * stopped, p->p_wchan will be 0 upon return from CURSIG.
  	 */
  	if (catch) {
 -		SCHED_UNLOCK(s);
 +		XXX_SCHED_UNLOCK;
  		l->l_flag |= L_SINTR;
  		if (((sig = CURSIG(l)) != 0) ||
  		    ((p->p_flag & P_WEXIT) && p->p_nlwps > 1)) {
 -			SCHED_LOCK(s);
 +			XXX_SCHED_LOCK;
  			if (l->l_wchan != NULL)
  				unsleep(l);
  			l->l_stat = LSONPROC;
 -			SCHED_UNLOCK(s);
 +			XXX_SCHED_UNLOCK;
  			goto resume;
  		}
  		if (l->l_wchan == NULL) {
  			catch = 0;
  			goto resume;
  		}
 -		SCHED_LOCK(s);
 +		XXX_SCHED_LOCK;
  	} else
  		sig = 0;
  	l->l_stat = LSSLEEP;
 @@ -1017,6 +1025,13 @@
  	microtime(&l->l_cpu->ci_schedstate.spc_runtime);
  
  	/*
 +	 * Reacquire the kernel_lock now.  We do this after we've
 +	 * released the scheduler lock to avoid deadlock, and before
 +	 * we reacquire the interlock.
 +	 */
 +	KERNEL_LOCK_ACQUIRE_COUNT(hold_count);
 +
 +	/*
  	 * Check if the process exceeds its CPU resource allocation.
  	 * If over max, kill it.  In any case, if it has run for more
  	 * than 10 minutes, reduce priority to give others a chance.
 @@ -1039,13 +1054,6 @@
  		SCHED_UNLOCK(s);
  	}
  
 -	/*
 -	 * Reacquire the kernel_lock now.  We do this after we've
 -	 * released the scheduler lock to avoid deadlock, and before
 -	 * we reacquire the interlock.
 -	 */
 -	KERNEL_LOCK_ACQUIRE_COUNT(hold_count);
 -
  	return retval;
  }