Re: [PATCH 13/13] libnvdimm, namespace: Publish page structure init state / control

[Matthew Wilcox <willy@xxxxxxxxxxxxx>]

On Thu, Jul 05, 2018 at 07:46:05AM -0700, Dan Williams wrote:
> On Thu, Jul 5, 2018 at 1:29 AM, Johannes Thumshirn <jthumshirn@xxxxxxx> wrote:
> > On Wed, Jul 04, 2018 at 11:50:13PM -0700, Dan Williams wrote:
> >> +static ssize_t memmap_state_store(struct device *dev,
> >> +             struct device_attribute *attr, const char *buf, size_t len)
> >> +{
> >> +     int i;
> >> +     struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
> >> +     struct memmap_async_state *async = &nd_pfn->async;
> >> +
> >> +     if (strcmp(buf, "sync") == 0)
> >> +             /* pass */;
> >> +     else if (strcmp(buf, "sync\n") == 0)
> >> +             /* pass */;
> >> +     else
> >> +             return -EINVAL;
> >
> > Hmm what about:
> >
> >         if (strncmp(buf, "sync", 4))
> >            return -EINVAL;
> >
> > This collapses 6 lines into 4.
> 
> ...but that also allows 'echo "syncAndThenSomeGarbage" >
> /sys/.../memmap_state' to succeed.

	if (strncmp(buf, "sync", 4))
		return -EINVAL;
	if (buf[4] != '\0' && buf[4] != '\n')
		return -EINVAL;