linux-kernel - Re: [PATCH 1/1] lib/test_vmalloc: do not create cpumask

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Date:   Fri, 19 Apr 2019 13:06:56 +0200
From:   Uladzislau Rezki <urezki@...il.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     "Uladzislau Rezki (Sony)" <urezki@...il.com>,
        Roman Gushchin <guro@...com>, Michal Hocko <mhocko@...e.com>,
        Matthew Wilcox <willy@...radead.org>, linux-mm@...ck.org,
        LKML <linux-kernel@...r.kernel.org>,
        Thomas Garnier <thgarnie@...gle.com>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...ymobile.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Joel Fernandes <joelaf@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...e.hu>, Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH 1/1] lib/test_vmalloc: do not create cpumask_t variable
 on stack

On Thu, Apr 18, 2019 at 03:10:33PM -0700, Andrew Morton wrote:
> On Thu, 18 Apr 2019 21:39:25 +0200 "Uladzislau Rezki (Sony)" <urezki@...il.com> wrote:
> 
> > On my "Intel(R) Xeon(R) W-2135 CPU @ 3.70GHz" system(12 CPUs)
> > i get the warning from the compiler about frame size:
> > 
> > <snip>
> > warning: the frame size of 1096 bytes is larger than 1024 bytes
> > [-Wframe-larger-than=]
> > <snip>
> > 
> > the size of cpumask_t depends on number of CPUs, therefore just
> > make use of cpumask_of() in set_cpus_allowed_ptr() as a second
> > argument.
> > 
> > ...
> L
> > --- a/lib/test_vmalloc.c
> > +++ b/lib/test_vmalloc.c
> > @@ -383,14 +383,14 @@ static void shuffle_array(int *arr, int n)
> >  static int test_func(void *private)
> >  {
> >  	struct test_driver *t = private;
> > -	cpumask_t newmask = CPU_MASK_NONE;
> >  	int random_array[ARRAY_SIZE(test_case_array)];
> >  	int index, i, j, ret;
> >  	ktime_t kt;
> >  	u64 delta;
> >  
> > -	cpumask_set_cpu(t->cpu, &newmask);
> > -	set_cpus_allowed_ptr(current, &newmask);
> > +	ret = set_cpus_allowed_ptr(current, cpumask_of(t->cpu));
> > +	if (ret < 0)
> > +		pr_err("Failed to set affinity to %d CPU\n", t->cpu);
> >  
> >  	for (i = 0; i < ARRAY_SIZE(test_case_array); i++)
> >  		random_array[i] = i;
> 
> lgtm.
> 
> While we're in there...
> 
> 
> From: Andrew Morton <akpm@...ux-foundation.org>
> Subject: lib/test_vmalloc.c:test_func(): eliminate local `ret'
> 
> Local 'ret' is unneeded and was poorly named: the variable `ret' generally
> means the "the value which this function will return".
> 
> Cc: Roman Gushchin <guro@...com>
> Cc: Uladzislau Rezki <urezki@...il.com>
> Cc: Michal Hocko <mhocko@...e.com>
> Cc: Matthew Wilcox <willy@...radead.org>
> Cc: Thomas Garnier <thgarnie@...gle.com>
> Cc: Oleksiy Avramchenko <oleksiy.avramchenko@...ymobile.com>
> Cc: Steven Rostedt <rostedt@...dmis.org>
> Cc: Joel Fernandes <joelaf@...gle.com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...e.hu>
> Cc: Tejun Heo <tj@...nel.org>
> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
> ---
> 
>  lib/test_vmalloc.c |    8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
> 
> --- a/lib/test_vmalloc.c~a
> +++ a/lib/test_vmalloc.c
> @@ -384,12 +384,11 @@ static int test_func(void *private)
>  {
>  	struct test_driver *t = private;
>  	int random_array[ARRAY_SIZE(test_case_array)];
> -	int index, i, j, ret;
> +	int index, i, j;
>  	ktime_t kt;
>  	u64 delta;
>  
> -	ret = set_cpus_allowed_ptr(current, cpumask_of(t->cpu));
> -	if (ret < 0)
> +	if (set_cpus_allowed_ptr(current, cpumask_of(t->cpu)) < 0)
>  		pr_err("Failed to set affinity to %d CPU\n", t->cpu);
>  
>  	for (i = 0; i < ARRAY_SIZE(test_case_array); i++)
> @@ -415,8 +414,7 @@ static int test_func(void *private)
>  
>  		kt = ktime_get();
>  		for (j = 0; j < test_repeat_count; j++) {
> -			ret = test_case_array[index].test_func();
> -			if (!ret)
> +			if (!test_case_array[index].test_func())
>  				per_cpu_test_data[t->cpu][index].test_passed++;
>  			else
>  				per_cpu_test_data[t->cpu][index].test_failed++;
> _
> 
Agree with your slight update.

Thank you!

--
Vlad Rezki