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mtd: rawnand: Replace zero-length array with flexible-array member

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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 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200226222722.GA18020@embeddedor
This commit is contained in:
Gustavo A. R. Silva 2020-02-26 16:27:22 -06:00 committed by Miquel Raynal
parent c6fbcb7013
commit 49f1c33076
6 changed files with 6 additions and 6 deletions
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2
drivers/mtd/nand/raw/denali.h
View file

@ -328,7 +328,7 @@ struct denali_chip {
struct nand_chip chip;
struct list_head node;
unsigned int nsels;
struct denali_chip_sel sels[0];
struct denali_chip_sel sels[];
};
/**

2
drivers/mtd/nand/raw/marvell_nand.c
View file

@ -334,7 +334,7 @@ struct marvell_nand_chip {
int addr_cyc;
int selected_die;
unsigned int nsels;
struct marvell_nand_chip_sel sels[0];
struct marvell_nand_chip_sel sels[];
};
static inline struct marvell_nand_chip *to_marvell_nand(struct nand_chip *chip)

2
drivers/mtd/nand/raw/meson_nand.c
View file

@ -118,7 +118,7 @@ struct meson_nfc_nand_chip {
u8 *data_buf;
__le64 *info_buf;
u32 nsels;
u8 sels[0];
u8 sels[];
};
struct meson_nand_ecc {

2
drivers/mtd/nand/raw/mtk_nand.c
View file

@ -131,7 +131,7 @@ struct mtk_nfc_nand_chip {
u32 spare_per_sector;
int nsels;
u8 sels[0];
u8 sels[];
/* nothing after this field */
};

2
drivers/mtd/nand/raw/nand_hynix.c
View file

@ -26,7 +26,7 @@
struct hynix_read_retry {
int nregs;
const u8 *regs;
u8 values[0];
u8 values[];
};
/**

2
drivers/mtd/nand/raw/sunxi_nand.c
View file

@ -195,7 +195,7 @@ struct sunxi_nand_chip {
u32 timing_cfg;
u32 timing_ctl;
int nsels;
struct sunxi_nand_chip_sel sels[0];
struct sunxi_nand_chip_sel sels[];
};
static inline struct sunxi_nand_chip *to_sunxi_nand(struct nand_chip *nand)