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

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Date:	Fri, 29 Jan 2016 09:46:03 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	"Zengtao (B)" <prime.zeng@...ilicon.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>,
	Frederic Weisbecker <fweisbec@...il.com>
Subject: Re: [PATCH] cputime: Fix timeval-->cputime conversion

On Friday 29 January 2016 03:12:37 Zengtao wrote:
> > -----Original Message-----
> > From: Arnd Bergmann [mailto:arnd@...db.de]
> > Sent: Thursday, January 28, 2016 7:52 PM
> > To: Thomas Gleixner
> > Cc: Zengtao (B); LKML; Frederic Weisbecker
> > Subject: Re: [PATCH] cputime: Fix timeval-->cputime conversion
> > 
> > On Thursday 28 January 2016 09:22:04 Thomas Gleixner wrote:
> > > Cc'ing Arnd
> > >
> > > On Thu, 28 Jan 2016, zengtao wrote:
> > >
> > > > The structure:
> > > > struct timeval {
> > > >       __kernel_time_t         tv_sec;         /* seconds */
> > > >       __kernel_suseconds_t    tv_usec;        /* microseconds */
> > > > };
> > > > both __kernel_time_t and __kernel_suseconds_t are short than u64
> > > > when it is 32bit platform, so force u64 conversion here.
> > > >
> > > > Signed-off-by: zengtao <prime.zeng@...wei.com>
> > >
> > > Reviewed-by: Thomas Gleixner <tglx@...utronix.de>
> > 
> > This seems to miss timespec_to_cputime(), which has the same problem,
> > so only setitimer() is fixed, but not nanosleep() or timer_settime().
> Yes, I have checked the code just now, the timespec_to_cputime() has the 
> same problem.I found the origin issue through setitimer().And I think the 
> timespec_to_cputime() only affects timer_settime(),by which means it affects 
> nanosleep? 

Reading that code again, I think it does not affect sys_nanosleep, but
it does affect sys_clock_nanosleep(CLOCK_PROCESS_CPUTIME_ID, ...)
along with timer_create/timer_settime with CLOCK_PROCESS_CPUTIME_ID.

	Arnd