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

[Gustavo A. R. Silva]

On 1/6/19 1:40 PM, Angelo Dureghello wrote:
> 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@xxxxxxxxxxxxxx>
> > ---
> >   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@xxxxxxxx>

Thanks, Angelo.

--
Gustavo