linux-kernel - [PATCH 1/6] cputime: Fix nsecs_to

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Date:	Thu,  6 Mar 2014 18:56:36 +0100
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	LKML <linux-kernel@...r.kernel.org>
Cc:	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...nel.org>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH 1/6] cputime: Fix nsecs_to_cputime() return type cast

Even though nsec based cputime_t maps to u64, nsecs_to_cputime() must
return a cputime_t value. We want to enforce this kind of cast in order
to track down buggy manipulations of cputime_t such as direct access
of its values under wrong assumptions on its backend type (nsecs,
jiffies, etc...) by core code.

Cc: Ingo Molnar <mingo@...nel.org>
Cc: Marcelo Tosatti <mtosatti@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
---
 include/asm-generic/cputime_nsecs.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/asm-generic/cputime_nsecs.h b/include/asm-generic/cputime_nsecs.h
index 2c9e62c..768294f 100644
--- a/include/asm-generic/cputime_nsecs.h
+++ b/include/asm-generic/cputime_nsecs.h
@@ -44,7 +44,8 @@ typedef u64 __nocast cputime64_t;
 /*
  * Convert cputime <-> nanoseconds
  */
-#define nsecs_to_cputime(__nsecs)	((__force u64)(__nsecs))
+#define nsecs_to_cputime(__nsecs)	\
+	(__force cputime_t)(__nsecs)
 
 
 /*
-- 
1.8.3.1

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