[PATCH] phy: samsung: Use struct_size() in devm_kzalloc()

From: Gustavo A. R. Silva
Date: Wed Jun 05 2019 - 16:25:44 EST

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 samsung_usb2_phy_driver {
struct samsung_usb2_phy_instance instances[0];

instance = devm_kzalloc(dev, sizeof(struct samsung_usb2_phy_driver) + count *
sizeof(struct samsung_usb2_phy_instance), GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:

instance = devm_kzalloc(dev, struct_size(instance, instances, count), GFP_KERNEL);

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
drivers/phy/samsung/phy-samsung-usb2.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/phy/samsung/phy-samsung-usb2.c b/drivers/phy/samsung/phy-samsung-usb2.c
index ea818866985a..4616ec829900 100644
--- a/drivers/phy/samsung/phy-samsung-usb2.c
+++ b/drivers/phy/samsung/phy-samsung-usb2.c
@@ -159,9 +159,8 @@ static int samsung_usb2_phy_probe(struct platform_device *pdev)
if (!cfg)
return -EINVAL;

- drv = devm_kzalloc(dev, sizeof(struct samsung_usb2_phy_driver) +
- cfg->num_phys * sizeof(struct samsung_usb2_phy_instance),
+ drv = devm_kzalloc(dev, struct_size(drv, instances, cfg->num_phys),
if (!drv)
return -ENOMEM;