linux-kernel - [PATCH] regulator: da9063: Replace zero-length array with flexible-array member

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Message-ID: <20200211234710.GA29532@embeddedor>
Date:   Tue, 11 Feb 2020 17:47:10 -0600
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Support Opensource <support.opensource@...semi.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>
Cc:     linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Subject: [PATCH] regulator: da9063: Replace zero-length array with
 flexible-array member

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
inadvertenly introduced[3] to the codebase from now on.

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@...eddedor.com>
---
 drivers/regulator/da9063-regulator.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/regulator/da9063-regulator.c b/drivers/regulator/da9063-regulator.c
index 2b0c7a85306a..368f8ad2a9f9 100644
--- a/drivers/regulator/da9063-regulator.c
+++ b/drivers/regulator/da9063-regulator.c
@@ -119,7 +119,7 @@ struct da9063_regulator {
 struct da9063_regulators {
 	unsigned				n_regulators;
 	/* Array size to be defined during init. Keep at end. */
-	struct da9063_regulator			regulator[0];
+	struct da9063_regulator			regulator[];
 };
 
 /* BUCK modes for DA9063 */
-- 
2.25.0