| Message ID | 20200214172022.GA27490@embeddedor |
|---|---|
| State | New |
| Headers | show |
| Series | Input: tca6416-keypad - replace zero-length array with flexible-array member | expand |
diff --git a/drivers/input/keyboard/tca6416-keypad.c b/drivers/input/keyboard/tca6416-keypad.c index 2a14769de637..21758767ccf0 100644 --- a/drivers/input/keyboard/tca6416-keypad.c +++ b/drivers/input/keyboard/tca6416-keypad.c @@ -33,7 +33,7 @@ MODULE_DEVICE_TABLE(i2c, tca6416_id); struct tca6416_drv_data { struct input_dev *input; - struct tca6416_button data[0]; + struct tca6416_button data[]; }; struct tca6416_keypad_chip { @@ -48,7 +48,7 @@ struct tca6416_keypad_chip { int irqnum; u16 pinmask; bool use_polling; - struct tca6416_button buttons[0]; + struct tca6416_button buttons[]; }; static int tca6416_write_reg(struct tca6416_keypad_chip *chip, int reg, u16 val)
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> --- drivers/input/keyboard/tca6416-keypad.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)