[PATCH] md-linear: use struct_size() in kzalloc()

[PATCH] md-linear: use struct_size() in kzalloc()

[Gustavo A. R. Silva]

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/md/md-linear.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/md/md-linear.c b/drivers/md/md-linear.c
index d45c697c0ebe..5998d78aa189 100644
--- a/drivers/md/md-linear.c
+++ b/drivers/md/md-linear.c
@@ -96,8 +96,7 @@ static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks)
 	int i, cnt;
 	bool discard_supported = false;
 
-	conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(struct dev_info),
-			GFP_KERNEL);
+	conf = kzalloc(struct_size(conf, disks, raid_disks), GFP_KERNEL);
 	if (!conf)
 		return NULL;
 
-- 
2.20.1

Re: [PATCH] md-linear: use struct_size() in kzalloc()

[Song Liu]

On Mon, Jan 7, 2019 at 10:35 AM Gustavo A. R. Silva
<gustavo@embeddedor.com> 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>

Acked-by: Song Liu <songliubraving@fb.com>

> ---
>  drivers/md/md-linear.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/md/md-linear.c b/drivers/md/md-linear.c
> index d45c697c0ebe..5998d78aa189 100644
> --- a/drivers/md/md-linear.c
> +++ b/drivers/md/md-linear.c
> @@ -96,8 +96,7 @@ static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks)
>         int i, cnt;
>         bool discard_supported = false;
>
> -       conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(struct dev_info),
> -                       GFP_KERNEL);
> +       conf = kzalloc(struct_size(conf, disks, raid_disks), GFP_KERNEL);
>         if (!conf)
>                 return NULL;
>
> --
> 2.20.1
>

Re: [PATCH] md-linear: use struct_size() in kzalloc()

[Gustavo A. R. Silva]

Hi all,

Friendly ping:

Who can take this?

Thanks
--
Gustavo

On 1/7/19 5:01 PM, Song Liu wrote:
> On Mon, Jan 7, 2019 at 10:35 AM Gustavo A. R. Silva
> <gustavo@embeddedor.com> 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>
> 
> Acked-by: Song Liu <songliubraving@fb.com>
> 
>> ---
>>  drivers/md/md-linear.c | 3 +--
>>  1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/drivers/md/md-linear.c b/drivers/md/md-linear.c
>> index d45c697c0ebe..5998d78aa189 100644
>> --- a/drivers/md/md-linear.c
>> +++ b/drivers/md/md-linear.c
>> @@ -96,8 +96,7 @@ static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks)
>>         int i, cnt;
>>         bool discard_supported = false;
>>
>> -       conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(struct dev_info),
>> -                       GFP_KERNEL);
>> +       conf = kzalloc(struct_size(conf, disks, raid_disks), GFP_KERNEL);
>>         if (!conf)
>>                 return NULL;
>>
>> --
>> 2.20.1
>>

Re: [PATCH] md-linear: use struct_size() in kzalloc()

[Song Liu]

I will take it, and send pull request.

Thanks,
Song

On Tue, Jan 29, 2019 at 9:22 AM Gustavo A. R. Silva
<gustavo@embeddedor.com> wrote:
>
> Hi all,
>
> Friendly ping:
>
> Who can take this?
>
> Thanks
> --
> Gustavo
>
> On 1/7/19 5:01 PM, Song Liu wrote:
> > On Mon, Jan 7, 2019 at 10:35 AM Gustavo A. R. Silva
> > <gustavo@embeddedor.com> 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>
> >
> > Acked-by: Song Liu <songliubraving@fb.com>
> >
> >> ---
> >>  drivers/md/md-linear.c | 3 +--
> >>  1 file changed, 1 insertion(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/md/md-linear.c b/drivers/md/md-linear.c
> >> index d45c697c0ebe..5998d78aa189 100644
> >> --- a/drivers/md/md-linear.c
> >> +++ b/drivers/md/md-linear.c
> >> @@ -96,8 +96,7 @@ static struct linear_conf *linear_conf(struct mddev *mddev, int raid_disks)
> >>         int i, cnt;
> >>         bool discard_supported = false;
> >>
> >> -       conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(struct dev_info),
> >> -                       GFP_KERNEL);
> >> +       conf = kzalloc(struct_size(conf, disks, raid_disks), GFP_KERNEL);
> >>         if (!conf)
> >>                 return NULL;
> >>
> >> --
> >> 2.20.1
> >>

Re: [PATCH] md-linear: use struct_size() in kzalloc()

[Gustavo A. R. Silva]

On 1/29/19 4:10 PM, Song Liu wrote:
> I will take it, and send pull request.
> 

Thank you, Song.

--
Gustavo