[resend PATCH for 3.2] procfs: do not confuse jiffies with cputime64_t

[Michal Hocko <mhocko@suse.cz>]

Hmm, it seems that this bugfix (for 3.2) stalled. I guess that it is
primarily because it is multiarch fix.
I am sorry to bother you Andrew but could we push this through you,
please?

The full patch for reference:
---
>From 1fca39b21f3b344c90c30d98db6dcdcdc6815797 Mon Sep 17 00:00:00 2001
From: Andreas Schwab <schwab@linux-m68k.org>
Date: Mon, 12 Dec 2011 14:07:53 +0100
Subject: [PATCH] procfs: do not confuse jiffies with cputime64_t

get_{idle,iowait}_time are supposed to return cputime64_t values, not
jiffies.  Add usecs_to_cputime64 for this.

Signed-off-by: Andreas Schwab <schwab@linux-m68k.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
---
 arch/ia64/include/asm/cputime.h    |    1 +
 arch/powerpc/include/asm/cputime.h |    2 ++
 arch/s390/include/asm/cputime.h    |    2 ++
 fs/proc/stat.c                     |    4 ++--
 include/asm-generic/cputime.h      |    1 +
 5 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/ia64/include/asm/cputime.h b/arch/ia64/include/asm/cputime.h
index 6073b18..5a274af 100644
--- a/arch/ia64/include/asm/cputime.h
+++ b/arch/ia64/include/asm/cputime.h
@@ -60,6 +60,7 @@ typedef u64 cputime64_t;
  */
 #define cputime_to_usecs(__ct)		((__ct) / NSEC_PER_USEC)
 #define usecs_to_cputime(__usecs)	((__usecs) * NSEC_PER_USEC)
+#define usecs_to_cputime64(__usecs)	usecs_to_cputime(__usecs)
 
 /*
  * Convert cputime <-> seconds
diff --git a/arch/powerpc/include/asm/cputime.h b/arch/powerpc/include/asm/cputime.h
index 1cf20bd..98b7c4b 100644
--- a/arch/powerpc/include/asm/cputime.h
+++ b/arch/powerpc/include/asm/cputime.h
@@ -150,6 +150,8 @@ static inline cputime_t usecs_to_cputime(const unsigned long us)
 	return ct;
 }
 
+#define usecs_to_cputime64(us)		usecs_to_cputime(us)
+
 /*
  * Convert cputime <-> seconds
  */
diff --git a/arch/s390/include/asm/cputime.h b/arch/s390/include/asm/cputime.h
index 0814348..b9acaaa 100644
--- a/arch/s390/include/asm/cputime.h
+++ b/arch/s390/include/asm/cputime.h
@@ -87,6 +87,8 @@ usecs_to_cputime(const unsigned int m)
 	return (cputime_t) m * 4096;
 }
 
+#define usecs_to_cputime64(m)		usecs_to_cputime(m)
+
 /*
  * Convert cputime to milliseconds and back.
  */
diff --git a/fs/proc/stat.c b/fs/proc/stat.c
index 2a30d67..0855e6f 100644
--- a/fs/proc/stat.c
+++ b/fs/proc/stat.c
@@ -32,7 +32,7 @@ static cputime64_t get_idle_time(int cpu)
 		idle = kstat_cpu(cpu).cpustat.idle;
 		idle = cputime64_add(idle, arch_idle_time(cpu));
 	} else
-		idle = nsecs_to_jiffies64(1000 * idle_time);
+		idle = usecs_to_cputime64(idle_time);
 
 	return idle;
 }
@@ -46,7 +46,7 @@ static cputime64_t get_iowait_time(int cpu)
 		/* !NO_HZ so we can rely on cpustat.iowait */
 		iowait = kstat_cpu(cpu).cpustat.iowait;
 	else
-		iowait = nsecs_to_jiffies64(1000 * iowait_time);
+		iowait = usecs_to_cputime64(iowait_time);
 
 	return iowait;
 }
diff --git a/include/asm-generic/cputime.h b/include/asm-generic/cputime.h
index 62ce682..12a1764 100644
--- a/include/asm-generic/cputime.h
+++ b/include/asm-generic/cputime.h
@@ -40,6 +40,7 @@ typedef u64 cputime64_t;
  */
 #define cputime_to_usecs(__ct)		jiffies_to_usecs(__ct)
 #define usecs_to_cputime(__msecs)	usecs_to_jiffies(__msecs)
+#define usecs_to_cputime64(__msecs)	nsecs_to_jiffies64((__msecs) * 1000)
 
 /*
  * Convert cputime to seconds and back.
-- 
1.7.7.3


-- 
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9    
Czech Republic