Index: sys/sys/proc.h
===================================================================
--- sys/sys/proc.h
+++ sys/sys/proc.h
@@ -63,6 +63,7 @@
 #include <sys/signalvar.h>
 #ifndef _KERNEL
 #include <sys/time.h>			/* For structs itimerval, timeval. */
+#include <machine/atomic.h>		/* atomic_load_int/atomic_store_int */
 #else
 #include <sys/pcpu.h>
 #include <sys/systm.h>
@@ -540,7 +541,7 @@
 #define	TD_IS_SWAPPED(td)	((td)->td_inhibitors & TDI_SWAPPED)
 #define	TD_ON_LOCK(td)		((td)->td_inhibitors & TDI_LOCK)
 #define	TD_AWAITING_INTR(td)	((td)->td_inhibitors & TDI_IWAIT)
-#define	TD_IS_RUNNING(td)	((td)->td_state == TDS_RUNNING)
+#define	TD_IS_RUNNING(td)	(atomic_load_int(&(td)->td_state) == TDS_RUNNING)
 #define	TD_ON_RUNQ(td)		((td)->td_state == TDS_RUNQ)
 #define	TD_CAN_RUN(td)		((td)->td_state == TDS_CAN_RUN)
 #define	TD_IS_INHIBITED(td)	((td)->td_state == TDS_INHIBITED)
@@ -557,15 +558,15 @@
 	((td)->td_inhibitors & TDI_LOCK) != 0 ? "blocked" :		\
 	((td)->td_inhibitors & TDI_IWAIT) != 0 ? "iwait" : "yielding")
 
-#define	TD_SET_INHIB(td, inhib) do {			\
-	(td)->td_state = TDS_INHIBITED;			\
-	(td)->td_inhibitors |= (inhib);			\
+#define	TD_SET_INHIB(td, inhib) do {				\
+	atomic_store_int(&(td)->td_state, TDS_INHIBITED);	\
+	(td)->td_inhibitors |= (inhib);				\
 } while (0)
 
-#define	TD_CLR_INHIB(td, inhib) do {			\
-	if (((td)->td_inhibitors & (inhib)) &&		\
-	    (((td)->td_inhibitors &= ~(inhib)) == 0))	\
-		(td)->td_state = TDS_CAN_RUN;		\
+#define	TD_CLR_INHIB(td, inhib) do {				\
+	if (((td)->td_inhibitors & (inhib)) &&			\
+	    (((td)->td_inhibitors &= ~(inhib)) == 0))		\
+		atomic_store_int(&(td)->td_state, TDS_CAN_RUN);	\
 } while (0)
 
 #define	TD_SET_SLEEPING(td)	TD_SET_INHIB((td), TDI_SLEEPING)
@@ -581,9 +582,9 @@
 #define	TD_CLR_SUSPENDED(td)	TD_CLR_INHIB((td), TDI_SUSPENDED)
 #define	TD_CLR_IWAIT(td)	TD_CLR_INHIB((td), TDI_IWAIT)
 
-#define	TD_SET_RUNNING(td)	(td)->td_state = TDS_RUNNING
-#define	TD_SET_RUNQ(td)		(td)->td_state = TDS_RUNQ
-#define	TD_SET_CAN_RUN(td)	(td)->td_state = TDS_CAN_RUN
+#define	TD_SET_RUNNING(td)	atomic_store_int(&(td)->td_state, TDS_RUNNING)
+#define	TD_SET_RUNQ(td)		atomic_store_int(&(td)->td_state, TDS_RUNQ)
+#define	TD_SET_CAN_RUN(td)	atomic_store_int(&(td)->td_state, TDS_CAN_RUN)
 
 #define	TD_SBDRY_INTR(td) \
     (((td)->td_flags & (TDF_SEINTR | TDF_SERESTART)) != 0)