linux-kernel - Re: [PATCH tip/core/rcu 19/45] rcutorture: Print negatives for SRCU counter wraparound

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Date:	Wed, 7 May 2014 17:08:58 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	josh@...htriplett.org
Cc:	linux-kernel@...r.kernel.org, mingo@...nel.org,
	laijs@...fujitsu.com, dipankar@...ibm.com,
	akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
	niv@...ibm.com, tglx@...utronix.de, peterz@...radead.org,
	rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
	darren@...art.com, fweisbec@...il.com, oleg@...hat.com, sbw@....edu
Subject: Re: [PATCH tip/core/rcu 19/45] rcutorture: Print negatives for SRCU
 counter wraparound

On Wed, May 07, 2014 at 02:34:26PM -0700, josh@...htriplett.org wrote:
> On Mon, Apr 28, 2014 at 05:25:07PM -0700, Paul E. McKenney wrote:
> > From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
> > 
> > The srcu_torture_stats() function prints SRCU's per-CPU c[] array with
> > an unsigned format, which means that the number one less than zero is
> > a very large number.  This commit therefore prints this array with a
> > signed format in order to improve readability of the rcutorture output.
> > 
> > Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
> 
> Nit below; with that:
> Reviewed-by: Josh Triplett <josh@...htriplett.org>
> 
> >  kernel/rcu/rcutorture.c | 7 ++++---
> >  1 file changed, 4 insertions(+), 3 deletions(-)
> > 
> > diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
> > index 3845ea99ccd4..0141fcff6bb9 100644
> > --- a/kernel/rcu/rcutorture.c
> > +++ b/kernel/rcu/rcutorture.c
> > @@ -486,15 +486,16 @@ static void srcu_torture_barrier(void)
> >  
> >  static void srcu_torture_stats(char *page)
> >  {
> > +	long c0, c1;
> >  	int cpu;
> >  	int idx = srcu_ctl.completed & 0x1;
> >  
> >  	page += sprintf(page, "%s%s per-CPU(idx=%d):",
> >  		       torture_type, TORTURE_FLAG, idx);
> >  	for_each_possible_cpu(cpu) {
> > -		page += sprintf(page, " %d(%lu,%lu)", cpu,
> > -			       per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
> > -			       per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
> > +		c0 = (long)per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx];
> > +		c1 = (long)per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx];
> > +		page += sprintf(page, " %d(%ld,%ld)", cpu, c0, c1);
> 
> Nit: I'd suggest declaring the variables inside the loop, or not using
> intermediate variables at all.

Fair enough!  Can't see that I am gaining much by them.

							Thanx, Paul

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