[PATCH] dmaengine: st_fdma: use struct_size() in kzalloc()

[PATCH] dmaengine: st_fdma: 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/dma/st_fdma.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/dma/st_fdma.c b/drivers/dma/st_fdma.c
index 07c20aa2e955..df6b73028ecb 100644
--- a/drivers/dma/st_fdma.c
+++ b/drivers/dma/st_fdma.c
@@ -243,8 +243,7 @@ static struct st_fdma_desc *st_fdma_alloc_desc(struct st_fdma_chan *fchan,
 	struct st_fdma_desc *fdesc;
 	int i;
 
-	fdesc = kzalloc(sizeof(*fdesc) +
-			sizeof(struct st_fdma_sw_node) * sg_len, GFP_NOWAIT);
+	fdesc = kzalloc(struct_size(fdesc, node, sg_len), GFP_NOWAIT);
 	if (!fdesc)
 		return NULL;
 
-- 
2.20.1


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Re: [PATCH] dmaengine: st_fdma: use struct_size() in kzalloc()

[Patrice CHOTARD]

Hi Gustavo

On 1/4/19 7:43 PM, 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/dma/st_fdma.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/dma/st_fdma.c b/drivers/dma/st_fdma.c
> index 07c20aa2e955..df6b73028ecb 100644
> --- a/drivers/dma/st_fdma.c
> +++ b/drivers/dma/st_fdma.c
> @@ -243,8 +243,7 @@ static struct st_fdma_desc *st_fdma_alloc_desc(struct st_fdma_chan *fchan,
>  	struct st_fdma_desc *fdesc;
>  	int i;
>  
> -	fdesc = kzalloc(sizeof(*fdesc) +
> -			sizeof(struct st_fdma_sw_node) * sg_len, GFP_NOWAIT);
> +	fdesc = kzalloc(struct_size(fdesc, node, sg_len), GFP_NOWAIT);
>  	if (!fdesc)
>  		return NULL;
>  
> 


Acked-by: Patrice Chotard <patrice.chotard@st.com>

Thanks
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Re: [PATCH] dmaengine: st_fdma: use struct_size() in kzalloc()

[Gustavo A. R. Silva]

On 1/7/19 2:50 AM, Patrice CHOTARD wrote:
> Hi Gustavo
> 
> On 1/4/19 7:43 PM, 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:
>>

[..]

>>
>> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
>> ---
>>   drivers/dma/st_fdma.c | 3 +--
>>   1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/drivers/dma/st_fdma.c b/drivers/dma/st_fdma.c
>> index 07c20aa2e955..df6b73028ecb 100644
>> --- a/drivers/dma/st_fdma.c
>> +++ b/drivers/dma/st_fdma.c
>> @@ -243,8 +243,7 @@ static struct st_fdma_desc *st_fdma_alloc_desc(struct st_fdma_chan *fchan,
>>   	struct st_fdma_desc *fdesc;
>>   	int i;
>>   
>> -	fdesc = kzalloc(sizeof(*fdesc) +
>> -			sizeof(struct st_fdma_sw_node) * sg_len, GFP_NOWAIT);
>> +	fdesc = kzalloc(struct_size(fdesc, node, sg_len), GFP_NOWAIT);
>>   	if (!fdesc)
>>   		return NULL;
>>   
>>
> 
> 
> Acked-by: Patrice Chotard <patrice.chotard@st.com>
> 

Thanks, Patrice.

--
Gustavo

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