Messages in this thread | | | Date | Tue, 4 Jul 2017 11:17:31 +0200 | From | Peter Zijlstra <> | Subject | Re: [tip:sched/core] sched/cputime: Refactor the cputime_adjust() code |
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On Fri, Jun 30, 2017 at 06:10:35AM -0700, tip-bot for Gustavo A. R. Silva wrote: > Commit-ID: 72298e5c92c50edd8cb7cfda4519483ce65fa166 > Gitweb: http://git.kernel.org/tip/72298e5c92c50edd8cb7cfda4519483ce65fa166 > Author: Gustavo A. R. Silva <garsilva@embeddedor.com> > AuthorDate: Thu, 29 Jun 2017 13:41:28 -0500 > Committer: Ingo Molnar <mingo@kernel.org> > CommitDate: Fri, 30 Jun 2017 09:37:59 +0200 > > sched/cputime: Refactor the cputime_adjust() code > > Address a Coverity false positive, which is caused by overly > convoluted code: > > Value assigned to variable 'utime' at line 619:utime = rtime; > is overwritten at line 642:utime = rtime - stime; before it > can be used. This makes such variable assignment useless. > > Remove this variable assignment and refactor the code related. > > Addresses-Coverity-ID: 1371643 > Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com> > Cc: Frans Klaver <fransklaver@gmail.com> > Cc: Frederic Weisbecker <fweisbec@gmail.com> > Cc: Linus Torvalds <torvalds@linux-foundation.org> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Rik van Riel <riel@redhat.com> > Cc: Stanislaw Gruszka <sgruszka@redhat.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Wanpeng Li <wanpeng.li@hotmail.com> > Link: http://lkml.kernel.org/r/20170629184128.GA5271@embeddedgus > Signed-off-by: Ingo Molnar <mingo@kernel.org> > --- > kernel/sched/cputime.c | 16 +++++----------- > 1 file changed, 5 insertions(+), 11 deletions(-) > > diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c > index aea3135..67c70e2 100644 > --- a/kernel/sched/cputime.c > +++ b/kernel/sched/cputime.c > @@ -615,19 +615,13 @@ static void cputime_adjust(struct task_cputime *curr, > * userspace. Once a task gets some ticks, the monotonicy code at > * 'update' will ensure things converge to the observed ratio. > */ > - if (stime == 0) { > - utime = rtime; > - goto update; > + if (stime != 0) { > + if (utime == 0) > + stime = rtime; > + else > + stime = scale_stime(stime, rtime, stime + utime); > } > > - if (utime == 0) { > - stime = rtime; > - goto update; > - } > - > - stime = scale_stime(stime, rtime, stime + utime); > - > -update: > /* > * Make sure stime doesn't go backwards; this preserves monotonicity > * for utime because rtime is monotonic.
Argh, no... That code was perfectly fine. The new code otoh is convoluted crap.
It had the form:
if (exception1) deal with exception1
if (execption2) deal with exception2
do normal stuff
Which is as simple and straight forward as it gets.
The new code otoh reads like:
if (!exception1) { if (exception2) deal with exception 2 else do normal stuff }
which is absolute shit.
So NAK on this.
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