dmaengine: st_fdma: use struct_size() in kzalloc()

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 <[email protected]>

---
 drivers/dma/st_fdma.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

drivers/dma/st_fdma.c +0 -0

index 07c20aa2e955..df6b73028ecb 100644

Hi Gustavo

Quoted 4 lines · 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:

Quoted 14 lines

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
  drivers/dma/st_fdma.c | 3 +--
  1 file changed, 1 insertion(+), 2 deletions(-)

drivers/dma/st_fdma.c +0 -0

index 07c20aa2e955..df6b73028ecb 100644
@@ -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;
 

drivers/dma/st_fdma.c static struct st_fdma_desc *st_fdma_alloc_desc(struct st_fdma_chan *fchan, · line 249

Quoted 7 lines

drivers/dma/st_fdma.c +1 -2

-	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 <[email protected]>