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:
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@ -75,7 +75,7 @@ struct sdhci_acpi_host {
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bool use_runtime_pm;
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bool is_intel;
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bool reset_signal_volt_on_suspend;
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unsigned long private[0] ____cacheline_aligned;
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unsigned long private[] ____cacheline_aligned;
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};
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enum {
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@ -68,7 +68,7 @@ struct sdhci_cdns_priv {
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void __iomem *hrs_addr;
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bool enhanced_strobe;
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unsigned int nr_phy_params;
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struct sdhci_cdns_phy_param phy_params[0];
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struct sdhci_cdns_phy_param phy_params[];
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};
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struct sdhci_cdns_phy_cfg {
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@ -163,7 +163,7 @@ struct sdhci_pci_slot {
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bool cd_override_level;
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void (*hw_reset)(struct sdhci_host *host);
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unsigned long private[0] ____cacheline_aligned;
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unsigned long private[] ____cacheline_aligned;
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};
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struct sdhci_pci_chip {
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@ -25,7 +25,7 @@ struct sdhci_pltfm_host {
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unsigned int clock;
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u16 xfer_mode_shadow;
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unsigned long private[0] ____cacheline_aligned;
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unsigned long private[] ____cacheline_aligned;
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};
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#ifdef CONFIG_MMC_SDHCI_BIG_ENDIAN_32BIT_BYTE_SWAPPER
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@ -614,7 +614,7 @@ struct sdhci_host {
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u64 data_timeout;
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unsigned long private[0] ____cacheline_aligned;
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unsigned long private[] ____cacheline_aligned;
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};
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struct sdhci_ops {
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@ -95,7 +95,7 @@ struct sd_response_header {
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u8 port_number;
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u8 command_type;
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u8 command_index;
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u8 command_response[0];
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u8 command_response[];
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} __packed;
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struct sd_status_header {
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@ -468,7 +468,7 @@ struct mmc_host {
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/* Host Software Queue support */
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bool hsq_enabled;
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unsigned long private[0] ____cacheline_aligned;
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unsigned long private[] ____cacheline_aligned;
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};
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struct device_node;
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@ -25,7 +25,7 @@ struct sdio_func_tuple {
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struct sdio_func_tuple *next;
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unsigned char code;
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unsigned char size;
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unsigned char data[0];
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unsigned char data[];
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};
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/*
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@ -57,7 +57,7 @@ struct mmc_ioc_cmd {
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*/
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struct mmc_ioc_multi_cmd {
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__u64 num_of_cmds;
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struct mmc_ioc_cmd cmds[0];
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struct mmc_ioc_cmd cmds[];
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};
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#define MMC_IOC_CMD _IOWR(MMC_BLOCK_MAJOR, 0, struct mmc_ioc_cmd)
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