cputime: Bring cputime -> nsecs conversion

We already have nsecs_to_cputime(). Now we need to be able to convert
the other way around in order to fix a bug on steal time accounting.

Cc: Ingo Molnar <mingo@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

include/asm-generic/cputime_jiffies.h

@@ -15,8 +15,10 @@ typedef u64 __nocast cputime64_t;
 
 
 /*
- * Convert nanoseconds to cputime
+ * Convert nanoseconds <-> cputime
  */
+#define cputime_to_nsecs(__ct)		\
+	jiffies_to_nsecs(cputime_to_jiffies(__ct))
 #define nsecs_to_cputime64(__nsec)	\
 	jiffies64_to_cputime64(nsecs_to_jiffies64(__nsec))
 #define nsecs_to_cputime(__nsec)	\

include/asm-generic/cputime_nsecs.h

@@ -44,6 +44,8 @@ typedef u64 __nocast cputime64_t;
 /*
  * Convert cputime <-> nanoseconds
  */
+#define cputime_to_nsecs(__ct)		\
+	(__force u64)(__ct)
 #define nsecs_to_cputime(__nsecs)	\
 	(__force cputime_t)(__nsecs)
 

include/linux/cputime.h

@@ -3,6 +3,11 @@
 
 #include <asm/cputime.h>
 
+#ifndef cputime_to_nsecs
+# define cputime_to_nsecs(__ct)	\
+	(cputime_to_usecs(__ct) * NSEC_PER_USEC)
+#endif
+
 #ifndef nsecs_to_cputime
 # define nsecs_to_cputime(__nsecs)	\
 	usecs_to_cputime((__nsecs) / NSEC_PER_USEC)