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mtd: rawnand: sunxi: Use struct_size() in devm_kzalloc()

PATCH In review Gustavo A. R. Silva 2 participants 3 messages Jan 4, 2019

Subsystems (3)
Memory technology devices (MTD) Arm/Allwinner sunXi SoC support NAND flash
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Gustavo A. R. Silva

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#0 lore raw

PATCH 1/1 mtd: rawnand: sunxi: Use struct_size() in devm_kzalloc()

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 <[email protected]>
---
 drivers/mtd/nand/raw/sunxi_nand.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)
drivers/mtd/nand/raw/sunxi_nand.c +1 -4
index e828ee50a201..f66fffe663bf 100644
@@ -1870,10 +1870,7 @@ static int sunxi_nand_chip_init(struct device *dev, struct sunxi_nfc *nfc,
 		return -EINVAL;
 	}
 
-	chip = devm_kzalloc(dev,
-			    sizeof(*chip) +
-			    (nsels * sizeof(struct sunxi_nand_chip_sel)),
-			    GFP_KERNEL);
+	chip = devm_kzalloc(dev, struct_size(chip, sels, nsels), GFP_KERNEL);
 	if (!chip) {
 		dev_err(dev, "could not allocate chip\n");
 		return -ENOMEM;
Signature · 1 line
2.20.1
#1 lore raw

Hi Gustavo,

Quoted 29 lines · On Fri, 4 Jan 2019 11:26:37 -0600 "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 <[email protected]>
---
 drivers/mtd/nand/raw/sunxi_nand.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)
drivers/mtd/nand/raw/sunxi_nand.c +0 -0
index e828ee50a201..f66fffe663bf 100644
@@ -1870,10 +1870,7 @@ static int sunxi_nand_chip_init(struct device *dev, struct sunxi_nfc *nfc,
 		return -EINVAL;

drivers/mtd/nand/raw/sunxi_nand.c static int sunxi_nand_chip_init(struct device *dev, struct sunxi_nfc *nfc, · line 1876

Quoted 10 lines
drivers/mtd/nand/raw/sunxi_nand.c +1 -4
 	}
 
-	chip = devm_kzalloc(dev,
-			    sizeof(*chip) +
-			    (nsels * sizeof(struct sunxi_nand_chip_sel)),
-			    GFP_KERNEL);
+	chip = devm_kzalloc(dev, struct_size(chip, sels, nsels), GFP_KERNEL);
 	if (!chip) {
 		dev_err(dev, "could not allocate chip\n");
 		return -ENOMEM;

I posted the same patch a few days back [1].

[1]http://patchwork.ozlabs.org/patch/1013855/