Re: [PATCH] dmaengine: fsl-edma: use struct_size() in kzalloc()

Angelo Dureghello
2019-01-06T19:50:57Z

On Fri, Jan 04, 2019 at 03:25:45PM -0600, 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/fsl-edma-common.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/dma/fsl-edma-common.c b/drivers/dma/fsl-edma-common.c
> index 8876c4c1bb2c..fe529100674f 100644
> --- a/drivers/dma/fsl-edma-common.c
> +++ b/drivers/dma/fsl-edma-common.c
> @@ -339,9 +339,7 @@ static struct fsl_edma_desc *fsl_edma_alloc_desc(struct fsl_edma_chan *fsl_chan,
> struct fsl_edma_desc *fsl_desc;
> int i;
>
> - fsl_desc = kzalloc(sizeof(*fsl_desc) +
> - sizeof(struct fsl_edma_sw_tcd) *
> - sg_len, GFP_NOWAIT);
> + fsl_desc = kzalloc(struct_size(fsl_desc, tcd, sg_len), GFP_NOWAIT);
> if (!fsl_desc)
> return NULL;
>

Tested-by: Angelo Dureghello <angelo@sysam.it>

> --
> 2.20.1
>