Re: [PATCH v9 5/7] ACPI: APEI: EINJ: Create debugfs files to enter device id and syndrome

[Dan Carpenter]

On Wed, Jun 18, 2025 at 08:30:10AM -0700, Luck, Tony wrote:
> On Wed, Jun 18, 2025 at 06:21:39PM +0300, Dan Carpenter wrote:
> > On Thu, Jun 12, 2025 at 04:13:25PM -0700, Zaid Alali wrote:
> > > +static ssize_t u128_read(struct file *f, char __user *buf, size_t count, loff_t *off)
> > > +{
> > > +	char output[2 * COMPONENT_LEN + 1];
> > > +	u8 *data = f->f_inode->i_private;
> > > +	int i;
> > > +
> > > +	if (*off >= sizeof(output))
> > > +		return 0;
> > 
> > No need for this check.  simple_read_from_buffer() will do the
> > right thing.
> 
> True. But why waste cycles populating the output buffer
> when it will be ignored? The normal flow here is that
> a user will likely try to read a <stdio.h> sized buffer
> and get back 33 bytes. Then read again to find EOF. That
> second read doesn't need to do all the "sprintf()"s.
> 

Ah.  Okay, I didn't realize that.

regards,
dan carpenter