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;
struct boo entry[];
};
size = sizeof(struct foo) + count * sizeof(struct boo);
instance = kzalloc(size, 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);
Notice that, in this case, variable size is not necessary, hence
it is removed.
This code was detected with the help of Coccinelle.
Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
---
drivers/usb/dwc2/hcd.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
index dd82fa516f3f..3f087962f498 100644
--- a/drivers/usb/dwc2/hcd.c
+++ b/drivers/usb/dwc2/hcd.c
@@ -3981,10 +3981,8 @@ static struct dwc2_hcd_urb *dwc2_hcd_urb_alloc(struct dwc2_hsotg *hsotg,
gfp_t mem_flags)
{
struct dwc2_hcd_urb *urb;
- u32 size = sizeof(*urb) + iso_desc_count *
- sizeof(struct dwc2_hcd_iso_packet_desc);
- urb = kzalloc(size, mem_flags);
+ urb = kzalloc(struct_size(urb, iso_descs, iso_desc_count), mem_flags);
if (urb)
urb->packet_count = iso_desc_count;
return urb;
--
2.20.1
