From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Mon, 18 Jul 2016 09:07:35 +0200 From: Martin Schwidefsky Subject: Re: [patch] s390/smp: clean up a condition In-Reply-To: <20160714104022.GF18175@mwanda> References: <20160714104022.GF18175@mwanda> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Message-Id: <20160718090735.103390c9@mschwide> Sender: linux-kernel-owner@vger.kernel.org List-Archive: List-Post: To: Dan Carpenter Cc: Heiko Carstens , Michael Holzheu , Thomas Gleixner , Hendrik Brueckner , "Peter Zijlstra (Intel)" , Christian Borntraeger , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org List-ID: On Thu, 14 Jul 2016 13:40:22 +0300 Dan Carpenter wrote: > I can never remember precedence rules. Let's add some parenthesis so > this code is more clear. > > Signed-off-by: Dan Carpenter > --- > The original code is correct right? We didn't intend to say: > > sclp_max = sclp.max_cores * (sclp_max ?: nr_cpu_ids); > > diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c > index 5c8f7ca..35531fe 100644 > --- a/arch/s390/kernel/smp.c > +++ b/arch/s390/kernel/smp.c > @@ -887,7 +887,7 @@ void __init smp_fill_possible_mask(void) > > sclp_max = max(sclp.mtid, sclp.mtid_cp) + 1; > sclp_max = min(smp_max_threads, sclp_max); > - sclp_max = sclp.max_cores * sclp_max ?: nr_cpu_ids; > + sclp_max = (sclp.max_cores * sclp_max) ?: nr_cpu_ids; > possible = setup_possible_cpus ?: nr_cpu_ids; > possible = min(possible, sclp_max); > for (cpu = 0; cpu < possible && cpu < nr_cpu_ids; cpu++) > The code calculates the number of threads to use, then multiplies it with the number of cores to get the number of logical CPUs. If the product happens to be zero because the number of cores could not be determined, then nr_cpu_ids is going to be used. So the code is correct but with the parenthesis it is easier to read. Applied & thanks. -- blue skies, Martin. "Reality continues to ruin my life." - Calvin.