Index: sys/proc.h
===================================================================
--- sys/proc.h	(revision 213714)
+++ sys/proc.h	(working copy)
@@ -353,7 +353,7 @@
 #define	TDF_NEEDRESCHED	0x00010000 /* Thread needs to yield. */
 #define	TDF_NEEDSIGCHK	0x00020000 /* Thread may need signal delivery. */
 #define	TDF_NOLOAD	0x00040000 /* Ignore during load avg calculations. */
-#define	TDF_TIDHASH	0x00080000 /* Thread is on hash table. */
+#define	TDF_UNUSED19	0x00080000 /* --available-- */
 #define	TDF_THRWAKEUP	0x00100000 /* Libthr thread must not suspend itself. */
 #define	TDF_UNUSED21	0x00200000 /* --available-- */
 #define	TDF_SWAPINREQ	0x00400000 /* Swapin request due to wakeup. */
Index: kern/kern_thread.c
===================================================================
--- kern/kern_thread.c	(revision 213714)
+++ kern/kern_thread.c	(working copy)
@@ -746,25 +746,23 @@
 		    (p->p_flag & P_SINGLE_BOUNDARY) && return_instead)
 			return (ERESTART);
 
-		/* If thread will exit, flush its pending signals */
-		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)) {
-			PROC_SUNLOCK(p);
 			PROC_UNLOCK(p);
 			tidhash_remove(td);
 			PROC_LOCK(p);
+			tdsigcleanup(td);
 			PROC_SLOCK(p);
+			thread_stopped(p);
 			thread_exit();
 		}
+
+		PROC_SLOCK(p);
+		thread_stopped(p);
 		if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
 			if (p->p_numthreads == p->p_suspcount + 1) {
 				thread_lock(p->p_singlethread);
@@ -981,12 +979,7 @@
 tidhash_add(struct thread *td)
 {
 	rw_wlock(&tidhash_lock);
-	thread_lock(td);
-	if ((td->td_flags & TDF_TIDHASH) == 0) {
-		LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash);
-		td->td_flags |= TDF_TIDHASH;
-	}
-	thread_unlock(td);
+	LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash);
 	rw_wunlock(&tidhash_lock);
 }
 
@@ -994,11 +987,6 @@
 tidhash_remove(struct thread *td)
 {
 	rw_wlock(&tidhash_lock);
-	thread_lock(td);
-	if ((td->td_flags & TDF_TIDHASH) != 0) {
-		LIST_REMOVE(td, td_hash);
-		td->td_flags &= ~TDF_TIDHASH;
-	}
-	thread_unlock(td);
+	LIST_REMOVE(td, td_hash);
 	rw_wunlock(&tidhash_lock);
 }
Index: kern/kern_thr.c
===================================================================
--- kern/kern_thr.c	(revision 213657)
+++ kern/kern_thr.c	(working copy)
@@ -37,6 +37,7 @@
 #include <sys/proc.h>
 #include <sys/posix4.h>
 #include <sys/resourcevar.h>
+#include <sys/rwlock.h>
 #include <sys/sched.h>
 #include <sys/sysctl.h>
 #include <sys/smp.h>
@@ -45,7 +46,6 @@
 #include <sys/systm.h>
 #include <sys/sysproto.h>
 #include <sys/signalvar.h>
-#include <sys/sx.h>
 #include <sys/ucontext.h>
 #include <sys/thr.h>
 #include <sys/rtprio.h>
@@ -285,23 +285,23 @@
 		kern_umtx_wake(td, uap->state, INT_MAX, 0);
 	}
 
-	tidhash_remove(td);
-
+	rw_wlock(&tidhash_lock);
 	PROC_LOCK(p);
-	tdsigcleanup(td);
-	PROC_SLOCK(p);
-
 	/*
 	 * Shutting down last thread in the proc.  This will actually
 	 * call exit() in the trampoline when it returns.
 	 */
 	if (p->p_numthreads != 1) {
+		LIST_REMOVE(td, td_hash);
+		rw_wunlock(&tidhash_lock);
+		tdsigcleanup(td);
+		PROC_SLOCK(p);
 		thread_stopped(p);
 		thread_exit();
 		/* NOTREACHED */
 	}
-	PROC_SUNLOCK(p);
 	PROC_UNLOCK(p);
+	rw_wunlock(&tidhash_lock);
 	return (0);
 }
 
Index: kern/init_main.c
===================================================================
--- kern/init_main.c	(revision 213657)
+++ kern/init_main.c	(working copy)
@@ -443,7 +443,6 @@
 	 */
 	LIST_INSERT_HEAD(&allproc, p, p_list);
 	LIST_INSERT_HEAD(PIDHASH(0), p, p_hash);
-	LIST_INSERT_HEAD(TIDHASH(0), td, td_hash);
 	mtx_init(&pgrp0.pg_mtx, "process group", NULL, MTX_DEF | MTX_DUPOK);
 	p->p_pgrp = &pgrp0;
 	LIST_INSERT_HEAD(PGRPHASH(0), &pgrp0, pg_hash);
@@ -462,6 +461,7 @@
 	STAILQ_INIT(&p->p_ktr);
 	p->p_nice = NZERO;
 	td->td_tid = PID_MAX + 1;
+	LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash);
 	td->td_state = TDS_RUNNING;
 	td->td_pri_class = PRI_TIMESHARE;
 	td->td_user_pri = PUSER;
Index: kern/kern_kthread.c
===================================================================
--- kern/kern_kthread.c	(revision 213657)
+++ kern/kern_kthread.c	(working copy)
@@ -34,6 +34,7 @@
 #include <sys/mutex.h>
 #include <sys/proc.h>
 #include <sys/resourcevar.h>
+#include <sys/rwlock.h>
 #include <sys/signalvar.h>
 #include <sys/sx.h>
 #include <sys/unistd.h>
@@ -315,17 +316,20 @@
 
 	p = curthread->td_proc;
 
-	tidhash_remove(curthread);
 
 	/* A module may be waiting for us to exit. */
 	wakeup(curthread);
+	rw_wlock(&tidhash_lock);
 	PROC_LOCK(p);
 	if (p->p_numthreads == 1) {
 		PROC_UNLOCK(p);
+		rw_wunlock(&tidhash_lock);
 		kproc_exit(0);
 
 		/* NOTREACHED. */
 	}
+	LIST_REMOVE(curthread, td_hash);
+	rw_wunlock(&tidhash_lock);
 	PROC_SLOCK(p);
 	thread_exit();
 }