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@xxxxxxxxxxxxxx>
> ---
>  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@xxxxxx>

Thanks