Index: sys/kern/kern_sig.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/kern_sig.c,v
retrieving revision 1.318
diff -u -r1.318 kern_sig.c
--- sys/kern/kern_sig.c	9 Dec 2005 08:29:29 -0000	1.318
+++ sys/kern/kern_sig.c	21 Dec 2005 08:29:43 -0000
@@ -2272,7 +2272,6 @@
 				goto out;
 			p->p_flag |= P_STOPPED_SIG;
 			p->p_xstat = sig;
-			p->p_xthread = td;
 			mtx_lock_spin(&sched_lock);
 			FOREACH_THREAD_IN_PROC(p, td0) {
 				if (TD_IS_SLEEPING(td0) &&
@@ -2599,7 +2598,6 @@
 				    &p->p_mtx.mtx_object, "Catching SIGSTOP");
 				p->p_flag |= P_STOPPED_SIG;
 				p->p_xstat = sig;
-				p->p_xthread = td;
 				mtx_lock_spin(&sched_lock);
 				FOREACH_THREAD_IN_PROC(p, td0) {
 					if (TD_IS_SLEEPING(td0) &&
Index: sys/kern/sys_process.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/sys_process.c,v
retrieving revision 1.133
diff -u -r1.133 sys_process.c
--- sys/kern/sys_process.c	8 Nov 2005 23:28:12 -0000	1.133
+++ sys/kern/sys_process.c	21 Dec 2005 08:29:43 -0000
@@ -637,7 +637,9 @@
 		}
 
 		/* not currently stopped */
-		if (!P_SHOULDSTOP(p) || p->p_suspcount != p->p_numthreads ||
+		if ((p->p_flag & (P_STOPPED_SIG | P_STOPPED_TRACE)) !=
+		     (P_STOPPED_SIG | P_STOPPED_TRACE) ||
+		    p->p_suspcount != p->p_numthreads  ||
 		    (p->p_flag & P_WAITED) == 0) {
 			error = EBUSY;
 			goto fail;
@@ -795,8 +797,14 @@
 		if (proctree_locked)
 			sx_xunlock(&proctree_lock);
 		/* deliver or queue signal */
-		if (P_SHOULDSTOP(p)) {
-			p->p_xstat = data;
+		if ((p->p_flag & P_STOPPED_TRACE) != 0) {
+			/*
+			 * We check flag P_STOPPED_TRACE to see if
+			 * it was stopped by debugger. If so, we can
+			 * exchange signal with the threads in the
+			 * process.
+			 */
+			KASSERT(p->p_xthread != NULL, ("NULL p_xthread"));
 			mtx_lock_spin(&sched_lock);
 			if (saved_pid <= PID_MAX) {
 				p->p_xthread->td_flags &= ~TDF_XSIG;
@@ -805,7 +813,12 @@
 				td2->td_flags &= ~TDF_XSIG;
 				td2->td_xsig = data;
 			}
-			p->p_xthread = NULL;
+			mtx_unlock_spin(&sched_lock);
+		}
+		p->p_xstat = data;
+		p->p_xthread = NULL;
+		if ((p->p_flag & (P_STOPPED_SIG | P_STOPPED_TRACE)) != 0) {
+			mtx_lock_spin(&sched_lock);
 			if (req == PT_DETACH) {
 				struct thread *td3;
 				FOREACH_THREAD_IN_PROC(p, td3)
@@ -818,15 +831,16 @@
 			 */
 			mtx_unlock_spin(&sched_lock);
 			thread_continued(p);
-			p->p_flag &= ~(P_STOPPED_TRACE|P_STOPPED_SIG);
+			p->p_flag &= ~(P_STOPPED_TRACE|P_STOPPED_SIG|P_WAITED);
 			mtx_lock_spin(&sched_lock);
 			thread_unsuspend(p);
 			mtx_unlock_spin(&sched_lock);
-		} else if (data) {
-			psignal(p, data);
 		}
-		PROC_UNLOCK(p);
 
+		if (data)
+			psignal(p, data);
+
+		PROC_UNLOCK(p);
 		return (0);
 
 	case PT_WRITE_I: