* [PATCH] eeprom: at24: use struct_size() in devm_kzalloc()
@ 2019-05-29 16:30 Gustavo A. R. Silva
2019-05-31 7:10 ` Bartosz Golaszewski
0 siblings, 1 reply; 2+ messages in thread
From: Gustavo A. R. Silva @ 2019-05-29 16:30 UTC (permalink / raw)
To: Bartosz Golaszewski, Arnd Bergmann, Greg Kroah-Hartman
Cc: linux-i2c, linux-kernel, 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;
struct boo entry[];
};
size = sizeof(struct foo) + count * sizeof(struct boo);
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, entry, count), GFP_KERNEL);
Notice that, in this case, variable at24_size is not necessary, hence it
is removed.
This code was detected with the help of Coccinelle.
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
drivers/misc/eeprom/at24.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index ba8e73812644..78ba6b1917a8 100644
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -568,7 +568,6 @@ static int at24_probe(struct i2c_client *client)
unsigned int i, num_addresses;
struct at24_data *at24;
struct regmap *regmap;
- size_t at24_size;
bool writable;
u8 test_byte;
int err;
@@ -652,8 +651,8 @@ static int at24_probe(struct i2c_client *client)
if (IS_ERR(regmap))
return PTR_ERR(regmap);
- at24_size = sizeof(*at24) + num_addresses * sizeof(struct at24_client);
- at24 = devm_kzalloc(dev, at24_size, GFP_KERNEL);
+ at24 = devm_kzalloc(dev, struct_size(at24, client, num_addresses),
+ GFP_KERNEL);
if (!at24)
return -ENOMEM;
--
2.21.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] eeprom: at24: use struct_size() in devm_kzalloc()
2019-05-29 16:30 [PATCH] eeprom: at24: use struct_size() in devm_kzalloc() Gustavo A. R. Silva
@ 2019-05-31 7:10 ` Bartosz Golaszewski
0 siblings, 0 replies; 2+ messages in thread
From: Bartosz Golaszewski @ 2019-05-31 7:10 UTC (permalink / raw)
To: Gustavo A. R. Silva; +Cc: Arnd Bergmann, Greg Kroah-Hartman, linux-i2c, LKML
śr., 29 maj 2019 o 18:30 Gustavo A. R. Silva <gustavo@embeddedor.com>
napisał(a):
>
> 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;
> struct boo entry[];
> };
>
> size = sizeof(struct foo) + count * sizeof(struct boo);
> 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, entry, count), GFP_KERNEL);
>
> Notice that, in this case, variable at24_size is not necessary, hence it
> is removed.
>
> This code was detected with the help of Coccinelle.
>
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> ---
> drivers/misc/eeprom/at24.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
> index ba8e73812644..78ba6b1917a8 100644
> --- a/drivers/misc/eeprom/at24.c
> +++ b/drivers/misc/eeprom/at24.c
> @@ -568,7 +568,6 @@ static int at24_probe(struct i2c_client *client)
> unsigned int i, num_addresses;
> struct at24_data *at24;
> struct regmap *regmap;
> - size_t at24_size;
> bool writable;
> u8 test_byte;
> int err;
> @@ -652,8 +651,8 @@ static int at24_probe(struct i2c_client *client)
> if (IS_ERR(regmap))
> return PTR_ERR(regmap);
>
> - at24_size = sizeof(*at24) + num_addresses * sizeof(struct at24_client);
> - at24 = devm_kzalloc(dev, at24_size, GFP_KERNEL);
> + at24 = devm_kzalloc(dev, struct_size(at24, client, num_addresses),
> + GFP_KERNEL);
> if (!at24)
> return -ENOMEM;
>
> --
> 2.21.0
>
Applied, thanks!
Bart
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