Index: sys/proc.h
===================================================================
--- sys/proc.h	(revision 184109)
+++ sys/proc.h	(working copy)
@@ -500,8 +500,8 @@
 	u_char		p_pfsflags;	/* (c) Procfs flags. */
 	struct nlminfo	*p_nlminfo;	/* (?) Only used by/for lockd. */
 	struct kaioinfo	*p_aioinfo;	/* (c) ASYNC I/O info. */
-	struct thread	*p_singlethread;/* (c + j) If single threading this is it */
-	int		p_suspcount;	/* (j) Num threads in suspended mode. */
+	struct thread	*p_singlethread;/* (c) If single threading this is it */
+	int		p_suspcount;	/* (c) Num threads in suspended mode. */
 	struct thread	*p_xthread;	/* (c) Trap thread */
 	int		p_boundary_count;/* (c) Num threads at user boundary */
 	int		p_pendingcnt;	/* how many signals are pending */
Index: kern/kern_thread.c
===================================================================
--- kern/kern_thread.c	(revision 184109)
+++ kern/kern_thread.c	(working copy)
@@ -543,7 +543,6 @@
 			p->p_flag &= ~P_SINGLE_BOUNDARY;
 	}
 	p->p_flag |= P_STOPPED_SINGLE;
-	PROC_SLOCK(p);
 	p->p_singlethread = td;
 	if (mode == SINGLE_EXIT)
 		remaining = p->p_numthreads;
@@ -642,7 +641,6 @@
 		p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT);
 		thread_unthread(td);
 	}
-	PROC_SUNLOCK(p);
 	return (0);
 }
 
@@ -716,15 +714,16 @@
 		if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td))
 			sigqueue_flush(&td->td_sigqueue);
 
-		PROC_SLOCK(p);
 		thread_stopped(p);
 		/*
 		 * If the process is waiting for us to exit,
 		 * this thread should just suicide.
 		 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE.
 		 */
-		if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td))
+		if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) {
+			PROC_SLOCK(p);
 			thread_exit();
+		}
 		if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
 			if (p->p_numthreads == p->p_suspcount + 1) {
 				thread_lock(p->p_singlethread);
@@ -735,8 +734,8 @@
 					kick_proc0();
 			}
 		}
-		PROC_UNLOCK(p);
 		thread_lock(td);
+		PROC_UNLOCK(p);
 		/*
 		 * When a thread suspends, it just
 		 * gets taken off all queues.
@@ -746,7 +745,6 @@
 			p->p_boundary_count++;
 			td->td_flags |= TDF_BOUNDARY;
 		}
-		PROC_SUNLOCK(p);
 		mi_switch(SW_INVOL | SWT_SUSPEND, NULL);
 		if (return_instead == 0)
 			td->td_flags &= ~TDF_BOUNDARY;
@@ -766,25 +764,22 @@
 	p = td->td_proc;
 	KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
 	PROC_LOCK_ASSERT(p, MA_OWNED);
-	PROC_SLOCK_ASSERT(p, MA_OWNED);
 	/*
 	 * We implement thread_suspend_one in stages here to avoid
 	 * dropping the proc lock while the thread lock is owned.
 	 */
 	thread_stopped(p);
 	p->p_suspcount++;
-	PROC_UNLOCK(p);
 	thread_lock(td);
+	PROC_UNLOCK(p);
 	td->td_flags &= ~TDF_NEEDSUSPCHK;
 	TD_SET_SUSPENDED(td);
 	sched_sleep(td, 0);
-	PROC_SUNLOCK(p);
 	DROP_GIANT();
 	mi_switch(SW_VOL | SWT_SUSPEND, NULL);
 	thread_unlock(td);
 	PICKUP_GIANT();
 	PROC_LOCK(p);
-	PROC_SLOCK(p);
 }
 
 void
@@ -792,7 +787,6 @@
 {
 	struct proc *p = td->td_proc;
 
-	PROC_SLOCK_ASSERT(p, MA_OWNED);
 	THREAD_LOCK_ASSERT(td, MA_OWNED);
 	KASSERT(!TD_IS_SUSPENDED(td), ("already suspended"));
 	p->p_suspcount++;
@@ -806,7 +800,6 @@
 {
 	struct proc *p = td->td_proc;
 
-	PROC_SLOCK_ASSERT(p, MA_OWNED);
 	THREAD_LOCK_ASSERT(td, MA_OWNED);
 	KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended"));
 	TD_CLR_SUSPENDED(td);
@@ -824,7 +817,6 @@
 	int wakeup_swapper;
 
 	PROC_LOCK_ASSERT(p, MA_OWNED);
-	PROC_SLOCK_ASSERT(p, MA_OWNED);
 	wakeup_swapper = 0;
 	if (!P_SHOULDSTOP(p)) {
                 FOREACH_THREAD_IN_PROC(p, td) {
@@ -863,7 +855,6 @@
 	p = td->td_proc;
 	PROC_LOCK_ASSERT(p, MA_OWNED);
 	p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY);
-	PROC_SLOCK(p);
 	p->p_singlethread = NULL;
 	wakeup_swapper = 0;
 	/*
@@ -881,7 +872,6 @@
 			thread_unlock(td);
 		}
 	}
-	PROC_SUNLOCK(p);
 	if (wakeup_swapper)
 		kick_proc0();
 }
Index: kern/kern_thr.c
===================================================================
--- kern/kern_thr.c	(revision 184109)
+++ kern/kern_thr.c	(working copy)
@@ -283,7 +283,6 @@
 
 	PROC_LOCK(p);
 	sigqueue_flush(&td->td_sigqueue);
-	PROC_SLOCK(p);
 
 	/*
 	 * Shutting down last thread in the proc.  This will actually
@@ -291,10 +290,10 @@
 	 */
 	if (p->p_numthreads != 1) {
 		thread_stopped(p);
+		PROC_SLOCK(p);
 		thread_exit();
 		/* NOTREACHED */
 	}
-	PROC_SUNLOCK(p);
 	PROC_UNLOCK(p);
 	return (0);
 }
Index: kern/kern_sig.c
===================================================================
--- kern/kern_sig.c	(revision 184109)
+++ kern/kern_sig.c	(working copy)
@@ -2115,19 +2115,15 @@
 			 * Otherwise, process goes back to sleep state.
 			 */
 			p->p_flag &= ~P_STOPPED_SIG;
-			PROC_SLOCK(p);
 			if (p->p_numthreads == p->p_suspcount) {
-				PROC_SUNLOCK(p);
 				p->p_flag |= P_CONTINUED;
 				p->p_xstat = SIGCONT;
 				PROC_LOCK(p->p_pptr);
 				childproc_continued(p);
 				PROC_UNLOCK(p->p_pptr);
-				PROC_SLOCK(p);
 			}
 			if (action == SIG_DFL) {
 				thread_unsuspend(p);
-				PROC_SUNLOCK(p);
 				sigqueue_delete(sigqueue, sig);
 				goto out;
 			}
@@ -2136,14 +2132,12 @@
 				 * The process wants to catch it so it needs
 				 * to run at least one thread, but which one?
 				 */
-				PROC_SUNLOCK(p);
 				goto runfast;
 			}
 			/*
 			 * The signal is not ignored or caught.
 			 */
 			thread_unsuspend(p);
-			PROC_SUNLOCK(p);
 			goto out;
 		}
 
@@ -2167,12 +2161,10 @@
 		 * It may run a bit until it hits a thread_suspend_check().
 		 */
 		wakeup_swapper = 0;
-		PROC_SLOCK(p);
 		thread_lock(td);
 		if (TD_ON_SLEEPQ(td) && (td->td_flags & TDF_SINTR))
 			wakeup_swapper = sleepq_abort(td, intrval);
 		thread_unlock(td);
-		PROC_SUNLOCK(p);
 		if (wakeup_swapper)
 			kick_proc0();
 		goto out;
@@ -2193,7 +2185,6 @@
 				goto out;
 			p->p_flag |= P_STOPPED_SIG;
 			p->p_xstat = sig;
-			PROC_SLOCK(p);
 			sig_suspend_threads(td, p, 1);
 			if (p->p_numthreads == p->p_suspcount) {
 				/*
@@ -2204,10 +2195,8 @@
 				 * should never be equal to p_suspcount.
 				 */
 				thread_stopped(p);
-				PROC_SUNLOCK(p);
 				sigqueue_delete_proc(p, p->p_xstat);
-			} else
-				PROC_SUNLOCK(p);
+			}
 			goto out;
 		}
 	} else {
@@ -2222,12 +2211,8 @@
 	 */
 runfast:
 	tdsigwakeup(td, sig, action, intrval);
-	PROC_SLOCK(p);
 	thread_unsuspend(p);
-	PROC_SUNLOCK(p);
 out:
-	/* If we jump here, proc slock should not be owned. */
-	PROC_SLOCK_ASSERT(p, MA_NOTOWNED);
 	return (ret);
 }
 
@@ -2247,7 +2232,6 @@
 	PROC_LOCK_ASSERT(p, MA_OWNED);
 	prop = sigprop(sig);
 
-	PROC_SLOCK(p);
 	thread_lock(td);
 	/*
 	 * Bring the priority of a thread up if we want it to get
@@ -2271,7 +2255,6 @@
 		 */
 		if ((prop & SA_CONT) && action == SIG_DFL) {
 			thread_unlock(td);
-			PROC_SUNLOCK(p);
 			sigqueue_delete(&p->p_sigqueue, sig);
 			/*
 			 * It may be on either list in this state.
@@ -2300,7 +2283,6 @@
 #endif
 	}
 out:
-	PROC_SUNLOCK(p);
 	thread_unlock(td);
 	if (wakeup_swapper)
 		kick_proc0();
@@ -2312,7 +2294,6 @@
 	struct thread *td2;
 
 	PROC_LOCK_ASSERT(p, MA_OWNED);
-	PROC_SLOCK_ASSERT(p, MA_OWNED);
 
 	FOREACH_THREAD_IN_PROC(p, td2) {
 		thread_lock(td2);
@@ -2344,11 +2325,9 @@
 
 	td->td_dbgflags |= TDB_XSIG;
 	td->td_xsig = sig;
-	PROC_SLOCK(p);
 	while ((p->p_flag & P_TRACED) && (td->td_dbgflags & TDB_XSIG)) {
 		if (p->p_flag & P_SINGLE_EXIT) {
 			td->td_dbgflags &= ~TDB_XSIG;
-			PROC_SUNLOCK(p);
 			return (sig);
 		}
 		/*
@@ -2370,7 +2349,6 @@
 			goto stopme;
 		}
 	}
-	PROC_SUNLOCK(p);
 	return (td->td_xsig);
 }
 
@@ -2511,10 +2489,8 @@
 				    &p->p_mtx.lock_object, "Catching SIGSTOP");
 				p->p_flag |= P_STOPPED_SIG;
 				p->p_xstat = sig;
-				PROC_SLOCK(p);
 				sig_suspend_threads(td, p, 0);
 				thread_suspend_switch(td);
-				PROC_SUNLOCK(p);
 				mtx_lock(&ps->ps_mtx);
 				break;
 			} else if (prop & SA_IGNORE) {
@@ -2556,18 +2532,15 @@
 	int n;
 
 	PROC_LOCK_ASSERT(p, MA_OWNED);
-	PROC_SLOCK_ASSERT(p, MA_OWNED);
 	n = p->p_suspcount;
 	if (p == curproc)
 		n++;
 	if ((p->p_flag & P_STOPPED_SIG) && (n == p->p_numthreads)) {
-		PROC_SUNLOCK(p);
 		p->p_flag &= ~P_WAITED;
 		PROC_LOCK(p->p_pptr);
 		childproc_stopped(p, (p->p_flag & P_TRACED) ?
 			CLD_TRAPPED : CLD_STOPPED);
 		PROC_UNLOCK(p->p_pptr);
-		PROC_SLOCK(p);
 	}
 }
  
Index: kern/subr_sleepqueue.c
===================================================================
--- kern/subr_sleepqueue.c	(revision 184109)
+++ kern/subr_sleepqueue.c	(working copy)
@@ -395,6 +395,8 @@
 		sleepq_switch(wchan, pri);
 		return (0);
 	}
+
+catch_sig:
 	thread_unlock(td);
 	mtx_unlock_spin(&sc->sc_lock);
 	CTR3(KTR_PROC, "sleepq catching signals: thread %p (pid %ld, %s)",
@@ -414,20 +416,19 @@
 			ret = ERESTART;
 		mtx_unlock(&ps->ps_mtx);
 	}
-	/*
-	 * Lock the per-process spinlock prior to dropping the PROC_LOCK
-	 * to avoid a signal delivery race.  PROC_LOCK, PROC_SLOCK, and
-	 * thread_lock() are currently held in tdsignal().
-	 */
-	PROC_SLOCK(p);
+	PROC_UNLOCK(p);
+
 	mtx_lock_spin(&sc->sc_lock);
-	PROC_UNLOCK(p);
 	thread_lock(td);
-	PROC_SUNLOCK(p);
-	if (ret == 0) {
-		sleepq_switch(wchan, pri);
-		return (0);
-	}
+	if (ret != 0)
+		goto out;
+	if ((td->td_flags & (TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK)) != 0)
+		goto catch_sig;
+
+	sleepq_switch(wchan, pri);
+	return (0);
+
+out:
 	/*
 	 * There were pending signals and this thread is still
 	 * on the sleep queue, remove it from the sleep queue.
Index: kern/sys_process.c
===================================================================
--- kern/sys_process.c	(revision 184109)
+++ kern/sys_process.c	(working copy)
@@ -795,10 +795,8 @@
 			 * you should use PT_SUSPEND to suspend it before
 			 * continuing process.
 			 */
-			PROC_SLOCK(p);
 			p->p_flag &= ~(P_STOPPED_TRACE|P_STOPPED_SIG|P_WAITED);
 			thread_unsuspend(p);
-			PROC_SUNLOCK(p);
 		} else {
 			if (data)
 				psignal(p, data);