[PATCH] revert adjtimex changes

From: John Stultz, George Anzinger, Eric Piel

There was confusion over the definition of TICK_USEC.  TICK_USEC is
supposed to be based on USER_HZ, however a recent change caused TICK_USEC
to be based on HZ.  This broke the adjtimex() interface on systems where
USER_HZ != HZ.  This patch reverts the change to TICK_USEC, removes an
added mis-use of the value and fixes some incorrect comments that could
lead to this sort of confusion.

Also this patch resolves the related LTP adjtimex failures.

include/asm-i386/mach-pc9800/setup_arch_pre.h

@@ -25,8 +25,8 @@ static  inline void arch_setup_pc9800(void)
 {
 	CLOCK_TICK_RATE = PC9800_8MHz_P() ? 1996800 : 2457600;
 	printk(KERN_DEBUG "CLOCK_TICK_RATE = %d\n", CLOCK_TICK_RATE);
-	tick_usec = TICK_USEC; 		/* ACTHZ          period (usec) */
-	tick_nsec = TICK_NSEC;		/* USER_HZ period (nsec) */
+	tick_usec = TICK_USEC; 		/* USER_HZ period (usec) */
+	tick_nsec = TICK_NSEC;		/* ACTHZ period (nsec) */
 
 	pc9800_misc_flags = PC9800_MISC_FLAGS;
 #ifdef CONFIG_SMP

include/linux/time.h

@@ -130,7 +130,8 @@ static __inline__ unsigned long
 timeval_to_jiffies(struct timeval *value)
 {
 	unsigned long sec = value->tv_sec;
-	long usec = value->tv_usec + TICK_USEC - 1;
+	long usec = value->tv_usec 
+		+ ((TICK_NSEC + 1000UL/2) / 1000UL) - 1;
 
 	if (sec >= MAX_SEC_IN_JIFFIES){
 		sec = MAX_SEC_IN_JIFFIES;

include/linux/timex.h

@@ -176,7 +176,7 @@
 #define TICK_NSEC (SH_DIV (1000000UL * 1000, ACTHZ, 8))
 
 /* TICK_USEC is the time between ticks in usec assuming fake USER_HZ */
-#define TICK_USEC ((TICK_NSEC + 1000UL/2) / 1000UL)
+#define TICK_USEC ((1000000UL + USER_HZ/2) / USER_HZ)
 
 /* TICK_USEC_TO_NSEC is the time between ticks in nsec assuming real ACTHZ and	*/
 /* a value TUSEC for TICK_USEC (can be set bij adjtimex)		*/

kernel/timer.c

@@ -439,8 +439,8 @@ static inline void __run_timers(tvec_base_t *base)
 /*
  * Timekeeping variables
  */
-unsigned long tick_usec = TICK_USEC; 		/* ACTHZ   period (usec) */
-unsigned long tick_nsec = TICK_NSEC;		/* USER_HZ period (nsec) */
+unsigned long tick_usec = TICK_USEC; 		/* USER_HZ period (usec) */
+unsigned long tick_nsec = TICK_NSEC;		/* ACTHZ period (nsec) */
 
 /* 
  * The current time