Add "clock_t_to_jiffies()" conversion function with

some rather minimal overflow protection. 

include/linux/times.h

@@ -11,6 +11,26 @@
 # define jiffies_to_clock_t(x) ((clock_t) jiffies_64_to_clock_t((u64) x))
 #endif
 
+static inline unsigned long clock_t_to_jiffies(unsigned long x)
+{
+#if (HZ % USER_HZ)==0
+	if (x >= ~0UL / (HZ / USER_HZ))
+		return ~0UL;
+	return x * (HZ / USER_HZ);
+#else
+	u64 jif;
+
+	/* Don't worry about loss of precision here .. */
+	if (x >= ~0UL / HZ * USER_HZ)
+		return ~0UL;
+
+	/* .. but do try to contain it here */
+	jif = x * (u64) HZ;
+	do_div(jif, USER_HZ);
+	return jif;
+#endif
+}
+
 static inline u64 jiffies_64_to_clock_t(u64 x)
 {
 #if (HZ % USER_HZ)==0