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From: Frederic Weisbecker <fweisbec@gmail.com>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
	Ingo Molnar <mingo@kernel.org>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: [PATCH 1/6] cputime: Fix nsecs_to_cputime() return type cast
Date: Thu,  6 Mar 2014 18:56:36 +0100	[thread overview]
Message-ID: <1394128601-26034-2-git-send-email-fweisbec@gmail.com> (raw)
In-Reply-To: <1394128601-26034-1-git-send-email-fweisbec@gmail.com>

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@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.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


  reply	other threads:[~2014-03-06 17:58 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-03-06 17:56 [PATCH 0/6] cputime: Fixes and cleanups on steal time accounting Frederic Weisbecker
2014-03-06 17:56 ` Frederic Weisbecker [this message]
2014-03-06 18:57   ` [PATCH 1/6] cputime: Fix nsecs_to_cputime() return type cast Rik van Riel
2014-03-12  2:14     ` Frederic Weisbecker
2014-03-06 17:56 ` [PATCH 2/6] cputime: Default implementation of nsecs -> cputime conversion Frederic Weisbecker
2014-03-06 19:17   ` Rik van Riel
2014-03-06 17:56 ` [PATCH 3/6] cputime: Bring cputime -> nsecs conversion Frederic Weisbecker
2014-03-06 19:24   ` Rik van Riel
2014-03-06 17:56 ` [PATCH 4/6] cputime: Fix jiffies based cputime assumption on steal accounting Frederic Weisbecker
2014-03-06 19:36   ` Rik van Riel
2014-03-06 17:56 ` [RFC PATCH 5/6] sched: Remove needless round trip nsecs <-> tick conversion of steal time Frederic Weisbecker
2014-03-06 19:39   ` Rik van Riel
2014-03-06 17:56 ` [PATCH 6/6] arch: Remove stub cputime.h headers Frederic Weisbecker
2014-03-06 19:40   ` Rik van Riel
2014-03-12  2:09 [GIT PULL] timers updates for 3.15 Frederic Weisbecker
2014-03-12  2:09 ` [PATCH 1/6] cputime: Fix nsecs_to_cputime() return type cast Frederic Weisbecker

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