[PATCH v2] kernel/power/hibernate.c: use 'u64' instead of 's64' to avoid warning

[Chen Gang <gang.chen.5i5j@gmail.com>]

For do_div(), it need 'u64' type, which means the outside must be sure
of 'start' is not bigger than 'stop', or it will report warning.

Even if 'start' was really bigger than 'stop', it would print incorrect
information, but for kernel, it still can continue, so use WARN_ON() is
enough.

The related warning (with allmodconfig for unicore32):

    CC      kernel/power/hibernate.o
  kernel/power/hibernate.c: In function ‘swsusp_show_speed’:
  kernel/power/hibernate.c:237: warning: comparison of distinct pointer types lacks a cast


Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
---
 kernel/power/hibernate.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index f4f2073..d5117d5 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -228,12 +228,13 @@ static void platform_recover(int platform_mode)
 void swsusp_show_speed(struct timeval *start, struct timeval *stop,
 			unsigned nr_pages, char *msg)
 {
-	s64 elapsed_centisecs64;
+	u64 elapsed_centisecs64;
 	int centisecs;
 	int k;
 	int kps;
 
 	elapsed_centisecs64 = timeval_to_ns(stop) - timeval_to_ns(start);
+	WARN_ON((s64)elapsed_centisecs64 < 0);
 	do_div(elapsed_centisecs64, NSEC_PER_SEC / 100);
 	centisecs = elapsed_centisecs64;
 	if (centisecs == 0)
-- 
1.9.2.459.g68773ac