linux-kernel - [PATCH] leds: pwm: Use struct

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Date:   Thu, 29 Aug 2019 19:53:20 -0500
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Jacek Anaszewski <jacek.anaszewski@...il.com>,
        Pavel Machek <pavel@....cz>, Dan Murphy <dmurphy@...com>
Cc:     linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        Kees Cook <keescook@...omium.org>
Subject: [PATCH] leds: pwm: Use struct_size() helper

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 led_pwm_priv {
	...
        struct led_pwm_data leds[0];
};

Make use of the struct_size() helper instead of an open-coded version
in order to avoid any potential type mistakes.

So, replace the following function:

static inline size_t sizeof_pwm_leds_priv(int num_leds)
{
       return sizeof(struct led_pwm_priv) +
                     (sizeof(struct led_pwm_data) * num_leds);
}

with:

struct_size(priv, leds, count)

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
---
 drivers/leds/leds-pwm.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c
index d0e1f2710351..8b6965a563e9 100644
--- a/drivers/leds/leds-pwm.c
+++ b/drivers/leds/leds-pwm.c
@@ -65,12 +65,6 @@ static int led_pwm_set(struct led_classdev *led_cdev,
 	return 0;
 }
 
-static inline size_t sizeof_pwm_leds_priv(int num_leds)
-{
-	return sizeof(struct led_pwm_priv) +
-		      (sizeof(struct led_pwm_data) * num_leds);
-}
-
 static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
 		       struct led_pwm *led, struct fwnode_handle *fwnode)
 {
@@ -174,7 +168,7 @@ static int led_pwm_probe(struct platform_device *pdev)
 	if (!count)
 		return -EINVAL;
 
-	priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count),
+	priv = devm_kzalloc(&pdev->dev, struct_size(priv, leds, count),
 			    GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;
-- 
2.23.0