linux-kernel - Re: [PATCH] cpufreq: e_powersaver: Use struct

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Message-ID: <1645829.9I2fkU6ktd@aspire.rjw.lan>
Date:   Thu, 24 Jan 2019 11:34:28 +0100
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Viresh Kumar <viresh.kumar@...aro.org>,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] cpufreq: e_powersaver: Use struct_size() in kzalloc()

On Tuesday, January 8, 2019 6:00:56 AM CET Viresh Kumar wrote:
> On 07-01-19, 11:33, Gustavo A. R. Silva wrote:
> > One of the more common cases of allocation size calculations is finding the
> > size of a structure that has a zero-sized array at the end, along with memory
> > for some number of elements for that array. For example:
> > 
> > struct foo {
> >     int stuff;
> >     void *entry[];
> > };
> > 
> > instance = kzalloc(sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);
> > 
> > Instead of leaving these open-coded and prone to type mistakes, we can now
> > use the new struct_size() helper:
> > 
> > instance = kzalloc(struct_size(instance, entry, count), GFP_KERNEL);
> > 
> > This code was detected with the help of Coccinelle.
> > 
> > Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
> > ---
> >  drivers/cpufreq/e_powersaver.c | 5 ++---
> >  1 file changed, 2 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/cpufreq/e_powersaver.c b/drivers/cpufreq/e_powersaver.c
> > index 60bea302abbe..2d3ef208dd70 100644
> > --- a/drivers/cpufreq/e_powersaver.c
> > +++ b/drivers/cpufreq/e_powersaver.c
> > @@ -323,9 +323,8 @@ static int eps_cpu_init(struct cpufreq_policy *policy)
> >  		states = 2;
> >  
> >  	/* Allocate private data and frequency table for current cpu */
> > -	centaur = kzalloc(sizeof(*centaur)
> > -		    + (states + 1) * sizeof(struct cpufreq_frequency_table),
> > -		    GFP_KERNEL);
> > +	centaur = kzalloc(struct_size(centaur, freq_table, states + 1),
> > +			  GFP_KERNEL);
> >  	if (!centaur)
> >  		return -ENOMEM;
> >  	eps_cpu[0] = centaur;
> 
> Acked-by: Viresh Kumar <viresh.kumar@...aro.org>

Patch applied, thanks!