linux-kernel - [PATCH] cputime: Fix timeval/timespec-->cputime conversion

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Date:	Tue, 2 Feb 2016 11:38:34 +0800
From:	zengtao <prime.zeng@...wei.com>
To:	<tglx@...utronix.de>, <arnd@...db.de>, <fweisbec@...il.com>
CC:	<linux-kernel@...r.kernel.org>
Subject: [PATCH] cputime: Fix timeval/timespec-->cputime conversion

The datatype __kernel_time_t is u32 on 32bit platform,
it will easily get overflow, so force u64 conversion.

Currently the following function will be affected:
1. setitimer()
2. timer_create/timer_settime()
3. sys_clock_nanosleep
And this will occur on MIPS32 and ARM32 with "Full dynticks CPU
time accounting" enabled, which is required for CONFIG_NO_HZ_FULL.

Signed-off-by: zengtao <prime.zeng@...wei.com>
---
 include/asm-generic/cputime_nsecs.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/asm-generic/cputime_nsecs.h b/include/asm-generic/cputime_nsecs.h
index 0419485..0f1c6f3 100644
--- a/include/asm-generic/cputime_nsecs.h
+++ b/include/asm-generic/cputime_nsecs.h
@@ -75,7 +75,7 @@ typedef u64 __nocast cputime64_t;
  */
 static inline cputime_t timespec_to_cputime(const struct timespec *val)
 {
-	u64 ret = val->tv_sec * NSEC_PER_SEC + val->tv_nsec;
+	u64 ret = (u64)val->tv_sec * NSEC_PER_SEC + val->tv_nsec;
 	return (__force cputime_t) ret;
 }
 static inline void cputime_to_timespec(const cputime_t ct, struct timespec *val)
@@ -91,7 +91,8 @@ static inline void cputime_to_timespec(const cputime_t ct, struct timespec *val)
  */
 static inline cputime_t timeval_to_cputime(const struct timeval *val)
 {
-	u64 ret = val->tv_sec * NSEC_PER_SEC + val->tv_usec * NSEC_PER_USEC;
+	u64 ret = (u64)val->tv_sec * NSEC_PER_SEC +
+			val->tv_usec * NSEC_PER_USEC;
 	return (__force cputime_t) ret;
 }
 static inline void cputime_to_timeval(const cputime_t ct, struct timeval *val)
-- 
1.9.1