[PATCH] set_task_state() UP memory barriers

This fixes the UP set_task_state and set_current_state in 2.5.43 to
ensure that we don't re-order loads around the store for setting
task->state.

This patch is from Nicolas Pitre, nico@cam.org

(As a side note - 2.4.10 also contains the same problem, but 2.2
contain the memory barrier.)

include/asm-arm/system.h

@@ -52,6 +52,8 @@ extern asmlinkage void __backtrace(void);
 #define mb() __asm__ __volatile__ ("" : : : "memory")
 #define rmb() mb()
 #define wmb() mb()
+#define set_mb(var, value)  do { var = value; mb(); } while (0)
+#define set_wmb(var, value) do { var = value; wmb(); } while (0)
 #define nop() __asm__ __volatile__("mov\tr0,r0\t@ nop\n\t");
 
 #define prepare_to_switch()    do { } while(0)

include/asm-cris/system.h

@@ -150,6 +150,8 @@ static inline unsigned long __xchg(unsigned long x, void * ptr, int size)
 #define mb() __asm__ __volatile__ ("" : : : "memory")
 #define rmb() mb()
 #define wmb() mb()
+#define set_mb(var, value)  do { var = value; mb(); } while (0)
+#define set_wmb(var, value) do { var = value; wmb(); } while (0)
 
 #ifdef CONFIG_SMP
 #define smp_mb()        mb()

include/asm-parisc/system.h

@@ -120,6 +120,8 @@ static inline void set_eiem(unsigned long val)
 
 #define mb()  __asm__ __volatile__ ("sync" : : :"memory")
 #define wmb() mb()
+#define set_mb(var, value)  do { var = value; mb(); } while (0)
+#define set_wmb(var, value) do { var = value; wmb(); } while (0)
 
 extern unsigned long __xchg(unsigned long, unsigned long *, int);
 

include/linux/sched.h

@@ -106,23 +106,13 @@ extern unsigned long nr_uninterruptible(void);
 
 #define __set_task_state(tsk, state_value)		\
 	do { (tsk)->state = (state_value); } while (0)
-#ifdef CONFIG_SMP
 #define set_task_state(tsk, state_value)		\
 	set_mb((tsk)->state, (state_value))
-#else
-#define set_task_state(tsk, state_value)		\
-	__set_task_state((tsk), (state_value))
-#endif
 
 #define __set_current_state(state_value)			\
 	do { current->state = (state_value); } while (0)
-#ifdef CONFIG_SMP
 #define set_current_state(state_value)		\
 	set_mb(current->state, (state_value))
-#else
-#define set_current_state(state_value)		\
-	__set_current_state(state_value)
-#endif
 
 /*
  * Scheduling policies