[03/12] usb: usbtmc: Add ioctls to set/get usb timeout

[Guido Kiener <guido@kiener-muenchen.de>]

Zitat von Andy Shevchenko <andy.shevchenko@gmail.com>:

> On Thu, May 17, 2018 at 8:03 PM, Guido Kiener  
> <guido@kiener-muenchen.de> wrote:
>> Add ioctls USBTMC_IOCTL_GET_TIMEOUT / USBTMC_IOCTL_SET_TIMEOUT to
>> get/set I/O timeout for specific file handle.
>
>
>
>
>> +static int usbtmc_ioctl_get_timeout(struct usbtmc_file_data *file_data,
>> +                               void __user *arg)
>> +{
>> +       __u32 timeout;
>> +
>> +       timeout = file_data->timeout;
>
> Why do you need __u32 on kernel side?
> Would plain u32 work?

It compiles and links with u32 and __u32 (and even double). AFAIK __u32 is for
user code and u32 for kernel code. So, correct is here what the  
maintainer says
or experienced kernel developers :-).
My opinion here is that put_user(..) and get_user(..) should always  
copy to the
same type to always have a safe copy operation from/to userland. So I prefer
__u32.

If you are sure that u32 is more correct here, then we use u32.

Best regards,

Guido

>
>> +
>> +       return put_user(timeout, (__u32 __user *)arg);
>> +}
>
>> +static int usbtmc_ioctl_set_timeout(struct usbtmc_file_data *file_data,
>> +                               void __user *arg)
>> +{
>> +       __u32 timeout;
>
> Ditto.
>
>> +       return 0;
>> +}
>
>
> --
> With Best Regards,
> Andy Shevchenko
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