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From: <Mario.Limonciello@dell.com>
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Subject: RE: [PATCH v10 13/15] platform/x86: wmi: create userspace interface
 for drivers
Thread-Topic: [PATCH v10 13/15] platform/x86: wmi: create userspace interface
 for drivers
Thread-Index: AQHTSaaCj0RVfg0GfEGxUsoMb9lFc6LswqRQ
Date: Fri, 20 Oct 2017 13:54:54 +0000
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References: <cover.1508434513.git.mario.limonciello@dell.com>
 <175838453318108ae69be344c4d3a2b75c2edc69.1508434514.git.mario.limonciello@dell.com>
 <20171020132242.GB23973@kroah.com>
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> -----Original Message-----
> From: Greg KH [mailto:greg@kroah.com]
> Sent: Friday, October 20, 2017 8:23 AM
> To: Limonciello, Mario <Mario_Limonciello@Dell.com>
> Cc: dvhart@infradead.org; Andy Shevchenko <andy.shevchenko@gmail.com>;
> LKML <linux-kernel@vger.kernel.org>; platform-driver-x86@vger.kernel.org; Andy
> Lutomirski <luto@kernel.org>; quasisec@google.com; pali.rohar@gmail.com;
> rjw@rjwysocki.net; mjg59@google.com; hch@lst.de; Alan Cox
> <gnomes@lxorguk.ukuu.org.uk>
> Subject: Re: [PATCH v10 13/15] platform/x86: wmi: create userspace interface for
> drivers
> 
> On Thu, Oct 19, 2017 at 12:50:16PM -0500, Mario Limonciello wrote:
> > +static ssize_t wmi_char_read(struct file *filp, char __user *buffer,
> > +	size_t length, loff_t *offset)
> > +{
> > +	struct wmi_block *wblock = filp->private_data;
> > +	size_t count;
> > +
> > +	if (*offset != 0)
> > +		return 0;
> > +
> > +	count = sizeof(wblock->req_buf_size);
> > +	count = length < count ? length : count;
> > +
> > +	if (copy_to_user(buffer, &wblock->req_buf_size, count))
> > +		return -EFAULT;
> > +
> > +	*offset = count;
> > +	return count;
> 
> simple_read_from_buffer()?  Library functions are your friend :)
> 
Thanks, wasn't aware of it.