Patchwork cpufreq: e_powersaver: Use struct_size() in kzalloc()

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Submitter Gustavo A. R. Silva
Date Jan. 7, 2019, 5:33 p.m.
Message ID <20190107173343.GA4258@embeddedor>
Download mbox | patch
Permalink /patch/694139/
State New
Headers show

Comments

Gustavo A. R. Silva - Jan. 7, 2019, 5:33 p.m.
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@embeddedor.com>
---
 drivers/cpufreq/e_powersaver.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)
Viresh Kumar - Jan. 8, 2019, 5 a.m.
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@embeddedor.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@linaro.org>
Rafael J. Wysocki - Jan. 24, 2019, 10:34 a.m.
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@embeddedor.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@linaro.org>

Patch applied, thanks!
Gustavo A. R. Silva - Jan. 24, 2019, 5:33 p.m.
On 1/24/19 4:34 AM, Rafael J. Wysocki wrote:
> 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@embeddedor.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@linaro.org>
> 
> Patch applied, thanks!
> 

Thank you both, Viresh and Rafael.

--
Gustavo

Patch

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;