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mmc: 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
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: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20200226223125.GA20630@embeddedor
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
This commit is contained in:
Gustavo A. R. Silva 2020-02-26 16:31:25 -06:00 committed by Ulf Hansson
parent ea21e9b2b3
commit 1a91a36aba
9 changed files with 9 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/mmc/host/sdhci-acpi.c
View File

@ -75,7 +75,7 @@ struct sdhci_acpi_host {
bool use_runtime_pm;
bool is_intel;
bool reset_signal_volt_on_suspend;
unsigned long private[0] ____cacheline_aligned;
unsigned long private[] ____cacheline_aligned;
};
enum {

2
drivers/mmc/host/sdhci-cadence.c
View File

@ -68,7 +68,7 @@ struct sdhci_cdns_priv {
void __iomem *hrs_addr;
bool enhanced_strobe;
unsigned int nr_phy_params;
struct sdhci_cdns_phy_param phy_params[0];
struct sdhci_cdns_phy_param phy_params[];
};
struct sdhci_cdns_phy_cfg {

2
drivers/mmc/host/sdhci-pci.h
View File

@ -163,7 +163,7 @@ struct sdhci_pci_slot {
bool cd_override_level;
void (*hw_reset)(struct sdhci_host *host);
unsigned long private[0] ____cacheline_aligned;
unsigned long private[] ____cacheline_aligned;
};
struct sdhci_pci_chip {

2
drivers/mmc/host/sdhci-pltfm.h
View File

@ -25,7 +25,7 @@ struct sdhci_pltfm_host {
unsigned int clock;
u16 xfer_mode_shadow;
unsigned long private[0] ____cacheline_aligned;
unsigned long private[] ____cacheline_aligned;
};
#ifdef CONFIG_MMC_SDHCI_BIG_ENDIAN_32BIT_BYTE_SWAPPER

2
drivers/mmc/host/sdhci.h
View File

@ -614,7 +614,7 @@ struct sdhci_host {
u64 data_timeout;
unsigned long private[0] ____cacheline_aligned;
unsigned long private[] ____cacheline_aligned;
};
struct sdhci_ops {

2
drivers/mmc/host/vub300.c
View File

@ -95,7 +95,7 @@ struct sd_response_header {
u8 port_number;
u8 command_type;
u8 command_index;
u8 command_response[0];
u8 command_response[];
} __packed;
struct sd_status_header {

2
include/linux/mmc/host.h
View File

@ -468,7 +468,7 @@ struct mmc_host {
/* Host Software Queue support */
bool hsq_enabled;
unsigned long private[0] ____cacheline_aligned;
unsigned long private[] ____cacheline_aligned;
};
struct device_node;

2
include/linux/mmc/sdio_func.h
View File

@ -25,7 +25,7 @@ struct sdio_func_tuple {
struct sdio_func_tuple *next;
unsigned char code;
unsigned char size;
unsigned char data[0];
unsigned char data[];
};
/*

2
include/uapi/linux/mmc/ioctl.h
View File

@ -57,7 +57,7 @@ struct mmc_ioc_cmd {
*/
struct mmc_ioc_multi_cmd {
__u64 num_of_cmds;
struct mmc_ioc_cmd cmds[0];
struct mmc_ioc_cmd cmds[];
};
#define MMC_IOC_CMD _IOWR(MMC_BLOCK_MAJOR, 0, struct mmc_ioc_cmd)