Hi Arnd,
On 21 September 2017 at 20:56, Arnd Bergmann <arnd@xxxxxxxx> wrote:
> On Thu, Sep 21, 2017 at 8:18 AM, Baolin Wang <baolin.wang@xxxxxxxxxx> wrote:
>
>> - case SNDRV_RAWMIDI_IOCTL_STATUS:
>> +#if __BITS_PER_LONG == 32
>> + case SNDRV_RAWMIDI_IOCTL_STATUS32:
>> + {
>> + int err = 0;
>> + struct snd_rawmidi_status32 __user *status = argp;
>> + struct snd_rawmidi_status32 status32;
>> + struct snd_rawmidi_status64 status64;
>> +
>> + if (copy_from_user(&status32, argp,
>> + sizeof(struct snd_rawmidi_status32)))
>> + return -EFAULT;
>> + switch (status32.stream) {
>> + case SNDRV_RAWMIDI_STREAM_OUTPUT:
>> + if (rfile->output == NULL)
>> + return -EINVAL;
>> + err = snd_rawmidi_output_status(rfile->output, &status64);
>> + break;
>> + case SNDRV_RAWMIDI_STREAM_INPUT:
>> + if (rfile->input == NULL)
>> + return -EINVAL;
>> + err = snd_rawmidi_input_status(rfile->input, &status64);
>> + break;
>> + default:
>> + return -EINVAL;
>> + }
>> + if (err < 0)
>> + return err;
>> +
>> + if (put_user(status64.stream, &status->stream) ||
>> + put_user(status64.tstamp.tv_sec, &status->tstamp.tv_sec) ||
>> + put_user(status64.tstamp.tv_nsec, &status->tstamp.tv_nsec) ||
>> + put_user(status64.avail, &status->avail) ||
>> + put_user(status64.xruns, &status->xruns))
>> + return -EFAULT;
>> + return 0;
>> + }
>
> This follows the existing coding style for the other functions, but I think
> it would be nicer to express the last part as
>
> status32 = (struct snd_rawmidi_status32) {
> .stream = status->stream,
> .tstamp.tv_sec, &status->tstamp.tv_sec,
> .tstamp.tv_nsec, &status->tstamp.tv_nsec,
> .avail, &status->avail,
> .xruns, &status->xruns,
> };
> if (copy_to_user(status, &status32, sizeof(*status))
> return -EFAULT;
> return 0;
>
> It's completely equivalent, I just find my version easier to read, and
> it should produce slightly better object code.
>
> Maybe the maintainers have a preference, or there might be
> a good reason to use the series of put_user() instead.
I just saw there are not many put_user() will be used in this
function, but I agree with you and I like to change as you suggested.
--
Baolin.wang
Best Regards
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