[PATCH] drm/amd/powerplay/smu10_hwmgr: use struct_size() in kzalloc()

[PATCH] drm/amd/powerplay/smu10_hwmgr: 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;
    struct boo entry[];
};

size = sizeof(struct foo) + count * sizeof(struct boo);
instance = kzalloc(size, 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);

Notice that, in this case, variable table_size is not necessary, hence
it is removed.

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c b/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c
index 5273de3c5b98..0ad8fe4a6277 100644
--- a/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c
+++ b/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c
@@ -139,12 +139,10 @@ static int smu10_construct_max_power_limits_table(struct pp_hwmgr *hwmgr,
 static int smu10_init_dynamic_state_adjustment_rule_settings(
 							struct pp_hwmgr *hwmgr)
 {
-	uint32_t table_size =
-		sizeof(struct phm_clock_voltage_dependency_table) +
-		(7 * sizeof(struct phm_clock_voltage_dependency_record));
+	struct phm_clock_voltage_dependency_table *table_clk_vlt;
 
-	struct phm_clock_voltage_dependency_table *table_clk_vlt =
-					kzalloc(table_size, GFP_KERNEL);
+	table_clk_vlt = kzalloc(struct_size(table_clk_vlt, entries, 7),
+				GFP_KERNEL);
 
 	if (NULL == table_clk_vlt) {
 		pr_err("Can not allocate memory!\n");
-- 
2.20.1

Re: [PATCH] drm/amd/powerplay/smu10_hwmgr: use struct_size() in kzalloc()

[Alex Deucher]

On Tue, Feb 19, 2019 at 1:55 PM 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;
>     struct boo entry[];
> };
>
> size = sizeof(struct foo) + count * sizeof(struct boo);
> instance = kzalloc(size, 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);
>
> Notice that, in this case, variable table_size is not necessary, hence
> it is removed.
>
> This code was detected with the help of Coccinelle.
>
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

Applied this and the smu8 patch.  Thanks!

Alex

> ---
>  drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c b/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c
> index 5273de3c5b98..0ad8fe4a6277 100644
> --- a/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c
> +++ b/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c
> @@ -139,12 +139,10 @@ static int smu10_construct_max_power_limits_table(struct pp_hwmgr *hwmgr,
>  static int smu10_init_dynamic_state_adjustment_rule_settings(
>                                                         struct pp_hwmgr *hwmgr)
>  {
> -       uint32_t table_size =
> -               sizeof(struct phm_clock_voltage_dependency_table) +
> -               (7 * sizeof(struct phm_clock_voltage_dependency_record));
> +       struct phm_clock_voltage_dependency_table *table_clk_vlt;
>
> -       struct phm_clock_voltage_dependency_table *table_clk_vlt =
> -                                       kzalloc(table_size, GFP_KERNEL);
> +       table_clk_vlt = kzalloc(struct_size(table_clk_vlt, entries, 7),
> +                               GFP_KERNEL);
>
>         if (NULL == table_clk_vlt) {
>                 pr_err("Can not allocate memory!\n");
> --
> 2.20.1
>
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

Re: [PATCH] drm/amd/powerplay/smu10_hwmgr: use struct_size() in kzalloc()

[Gustavo A. R. Silva]

On 2/19/19 1:51 PM, Alex Deucher wrote:
> On Tue, Feb 19, 2019 at 1:55 PM 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;
>>     struct boo entry[];
>> };
>>
>> size = sizeof(struct foo) + count * sizeof(struct boo);
>> instance = kzalloc(size, 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);
>>
>> Notice that, in this case, variable table_size is not necessary, hence
>> it is removed.
>>
>> This code was detected with the help of Coccinelle.
>>
>> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> 
> Applied this and the smu8 patch.  Thanks!
> 
Great!

Thanks, Alex.

--
Gustavo