[PATCH] i2c: mux: demux-pinctrl: 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 foo {
    int stuff;
    void *entry[];
};

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

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gust...@embeddedor.com>
---
 drivers/i2c/muxes/i2c-demux-pinctrl.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/muxes/i2c-demux-pinctrl.c 
b/drivers/i2c/muxes/i2c-demux-pinctrl.c
index 035032e20327..012b45e447c3 100644
--- a/drivers/i2c/muxes/i2c-demux-pinctrl.c
+++ b/drivers/i2c/muxes/i2c-demux-pinctrl.c
@@ -219,8 +219,8 @@ static int i2c_demux_pinctrl_probe(struct platform_device 
*pdev)
                return -EINVAL;
        }
 
-       priv = devm_kzalloc(&pdev->dev, sizeof(*priv)
-                          + num_chan * sizeof(struct i2c_demux_pinctrl_chan), 
GFP_KERNEL);
+       priv = devm_kzalloc(&pdev->dev, struct_size(priv, chan, num_chan),
+                           GFP_KERNEL);
 
        props = devm_kcalloc(&pdev->dev, num_chan, sizeof(*props), GFP_KERNEL);
 
-- 
2.20.1