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

Gustavo A. R. Silva
2019-01-06T20:34:01Z

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@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>
>

Thanks, Angelo.

--
Gustavo