[PATCH] better compat_jiffies_to_clock_t

By a suggestion from David Mosberger: use this new version of
compat_jiffies_to_clock_t, which is more appropriate on 64-bit hosts
that don't have overflow issues.

It does better rounding and will not fail if COMPAT_USER_HZ > HZ.

include/linux/compat.h

@@ -9,9 +9,11 @@
 #ifdef CONFIG_COMPAT
 
 #include <linux/stat.h>
+#include <linux/param.h>	/* for HZ */
 #include <asm/compat.h>
 
-#define compat_jiffies_to_clock_t(x)	((x) / (HZ / COMPAT_USER_HZ))
+#define compat_jiffies_to_clock_t(x)	\
+		(((unsigned long)(x) * COMPAT_USER_HZ) / HZ)
 
 struct compat_utimbuf {
 	compat_time_t		actime;