Re: [PATCH] Input: gpio_keys_polled - use struct_size() in devm_kzalloc()
From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Date: 2019-06-23 06:33:50
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On Wed, Jun 19, 2019 at 09:26:55AM -0500, Gustavo A. R. Silva wrote:
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 gpio_keys_polled_dev {
...
struct gpio_keys_button_data data[0];
};
size = sizeof(struct gpio_keys_polled_dev) + count * sizeof(struct gpio_keys_button_data);
instance = devm_kzalloc(dev, size, 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, data, 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 <redacted>Applied, thank you.
quoted hunk ↗ jump to hunk
--- drivers/input/keyboard/gpio_keys_polled.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)diff --git a/drivers/input/keyboard/gpio_keys_polled.c b/drivers/input/keyboard/gpio_keys_polled.c index edc7262103b9..c4087be0c2e0 100644 --- a/drivers/input/keyboard/gpio_keys_polled.c +++ b/drivers/input/keyboard/gpio_keys_polled.c@@ -235,7 +235,6 @@ static int gpio_keys_polled_probe(struct platform_device *pdev) struct gpio_keys_polled_dev *bdev; struct input_polled_dev *poll_dev; struct input_dev *input; - size_t size; int error; int i;@@ -250,9 +249,8 @@ static int gpio_keys_polled_probe(struct platform_device *pdev) return -EINVAL; } - size = sizeof(struct gpio_keys_polled_dev) + - pdata->nbuttons * sizeof(struct gpio_keys_button_data); - bdev = devm_kzalloc(dev, size, GFP_KERNEL); + bdev = devm_kzalloc(dev, struct_size(bdev, data, pdata->nbuttons), + GFP_KERNEL); if (!bdev) { dev_err(dev, "no memory for private data\n"); return -ENOMEM;-- 2.21.0
-- Dmitry