Re: [PATCH] pinctrl: uniphier: Replace zero-length array with flexible-array member
From: Masahiro Yamada <masahiroy@kernel.org>
Date: 2020-02-18 01:25:34
Also in:
linux-gpio, lkml
On Tue, Feb 18, 2020 at 3:52 AM Gustavo A. R. Silva [off-list ref] wrote:
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 <redacted>Acked-by: Masahiro Yamada <redacted>
quoted hunk ↗ jump to hunk
--- drivers/pinctrl/uniphier/pinctrl-uniphier-core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/drivers/pinctrl/uniphier/pinctrl-uniphier-core.c b/drivers/pinctrl/uniphier/pinctrl-uniphier-core.c index 57babf31e320..ade348b49b31 100644 --- a/drivers/pinctrl/uniphier/pinctrl-uniphier-core.c +++ b/drivers/pinctrl/uniphier/pinctrl-uniphier-core.c@@ -29,7 +29,7 @@ struct uniphier_pinctrl_reg_region { struct list_head node; unsigned int base; unsigned int nregs; - u32 vals[0]; + u32 vals[]; }; struct uniphier_pinctrl_priv { --2.25.0
-- Best Regards Masahiro Yamada _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel