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

[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:

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 <gust...@embeddedor.com>
---
 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),
-                                                               GFP_KERNEL);
+       drv = devm_kzalloc(dev, struct_size(drv, instances, cfg->num_phys),
+                          GFP_KERNEL);
        if (!drv)
                return -ENOMEM;
 
-- 
2.21.0