| Message ID | 20190529163052.GA29158@embeddedor |
|---|---|
| State | Accepted |
| Delegated to: | Bartosz Golaszewski |
| Headers | show |
| Series | eeprom: at24: use struct_size() in devm_kzalloc() | expand |
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
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;
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(-)