From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
To: Kukjin Kim <kgene@kernel.org>,
Krzysztof Kozlowski <krzk@kernel.org>,
Andi Shyti <andi@etezian.org>, Mark Brown <broonie@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
linux-samsung-soc@vger.kernel.org, linux-spi@vger.kernel.org,
linux-kernel@vger.kernel.org,
"Gustavo A. R. Silva" <gustavo@embeddedor.com>
Subject: [PATCH][next] spi: spi-s3c24xx: Replace zero-length array with flexible-array member
Date: Fri, 20 Mar 2020 18:25:56 -0500 [thread overview]
Message-ID: <20200320232556.GA24989@embeddedor.com> (raw)
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/spi/spi-s3c24xx.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/spi/spi-s3c24xx.c b/drivers/spi/spi-s3c24xx.c
index 2d6e37f25e2d..2cb3b611c294 100644
--- a/drivers/spi/spi-s3c24xx.c
+++ b/drivers/spi/spi-s3c24xx.c
@@ -227,7 +227,7 @@ static inline unsigned int hw_txbyte(struct s3c24xx_spi *hw, int count)
struct spi_fiq_code {
u32 length;
u32 ack_offset;
- u8 data[0];
+ u8 data[];
};
extern struct spi_fiq_code s3c24xx_spi_fiq_txrx;
--
2.23.0
next reply other threads:[~2020-03-20 23:25 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-20 23:25 Gustavo A. R. Silva [this message]
2020-03-22 20:46 ` [PATCH][next] spi: spi-s3c24xx: Replace zero-length array with flexible-array member Andi Shyti
2020-03-23 18:37 ` Applied "spi: spi-s3c24xx: Replace zero-length array with flexible-array member" to the spi tree Mark Brown
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