2011/4/14 John Calixto <[email protected]>:
[...]
> + /* DAT buffer */
> + __u32 data_ptr_size; /* size of the *pointer* */
> + __u64 data_ptr;
So... again... What's the problem with anonymous union of pointer and u64?
Example implementation:
struct mmc_ioc_cmd {
...
union {
void __user *data_ptr;
__u64 __data_ptr_storage;
};
};
static int mmc_blk_ioctl(struct block_device *bdev, fmode_t mode,
unsigned int cmd, unsigned long arg)
{
struct mmc_ioc_cmd blk;
if (cmd != MMC_IOC_CMD)
return -EINVAL;
copy_from_user((void __user *)arg, &blk) ...
return mmc_blk_ioctl_cmd(bdev, &blk);
}
static int mmc_blk_compat_ioctl(struct block_device *bdev, fmode_t
mode, unsigned int cmd, unsigned long arg)
{
struct mmc_ioc_cmd blk;
if (cmd != MMC_IOC_CMD)
return -EINVAL;
copy_from_user(compat_ptr(arg), &blk) ...
blk.data_ptr = compat_ptr(*(__u32 *)&blk.data_ptr);
return mmc_blk_ioctl_cmd(bdev, &blk);
}
Best Regards,
Michał Mirosław
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