Re: [PATCH] sched/numa: Fix divide by zero for sysctl_numa_balancing_scan_size.

[chris hyser]

On 3/29/23 21:51, Chen Yu wrote:
> On 2023-03-29 at 12:26:10 -0400, Chris Hyser wrote:
> > From: chris hyser <chris.hyser@xxxxxxxxxx>
> >
> > Commit 6419265899d9 ("sched/fair: Fix division by zero
> > sysctl_numa_balancing_scan_size") prevented a divide by zero by using
> > sysctl mechanisms to return EINVAL for a sysctl_numa_balancing_scan_size
> > value of zero. When moved from a sysctl to a debugfs file, this checking
> > was lost.
> >
> > This patch puts zero checking back in place.
> >
> > Signed-off-by: Chris Hyser <chris.hyser@xxxxxxxxxx>
> > ---
> >   kernel/sched/debug.c | 50 +++++++++++++++++++++++++++++++++++++++++++-
> >   1 file changed, 49 insertions(+), 1 deletion(-)
> >
> > diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
> > index 1637b65ba07a..dfd0fe6123ec 100644
> > --- a/kernel/sched/debug.c
> > +++ b/kernel/sched/debug.c
> > @@ -278,6 +278,54 @@ static const struct file_operations sched_dynamic_fops = {
> >   
> >   #endif /* CONFIG_PREEMPT_DYNAMIC */
> >   
> > +#ifdef CONFIG_NUMA_BALANCING
> > +
> > +static ssize_t sched_numa_scan_write(struct file *filp, const char __user *ubuf,
> > +				     size_t cnt, loff_t *ppos)
> > +{
> > +	char buf[16];
> > +	unsigned int scan_size;
> > +
> > +	if (cnt > 15)
> > +		cnt = 15;
> > +
> > +	if (copy_from_user(&buf, ubuf, cnt))
> > +		return -EFAULT;
> > +	buf[cnt] = '\0';
> > +
> > +	if (kstrtouint(buf, 10, &scan_size))
> > +		return -EINVAL;
> error code of kstrtouint() includes -ERANGE other than -EINVAL, how
> about return the error code directly?

Sure. I just sent out a v2.

-chrish

> thanks,
> Chenyu