On Mon 05-09-22 17:51:37, Ammar Faizi wrote:
> On Mon, 5 Sep 2022 05:10:12 +0200, Oscar Salvador wrote:
> > +static int page_owner_threshold_show(struct seq_file *p, void *v)
> > +{
> > + seq_printf(p, "%lu\n", threshold);
>
> Remove a slipped leading 0x20 space here (before seq_printf()).
>
> > + return 0;
> > +}
> > +
> > +static ssize_t write_page_owner_threshold(struct file *file, const char __user *buf,
> > + size_t count, loff_t *pos)
> > +{
> > + char *kbuf;
> > + int ret = 0;
> > +
> > + count = min_t(size_t, count, PAGE_SIZE);
> > + kbuf = kmalloc(count, GFP_KERNEL);
> > + if (!kbuf)
> > + return -ENOMEM;
> > +
> > + if (copy_from_user(kbuf, buf, count)) {
> > + ret = -EFAULT;
> > + goto out;
> > + }
> > +
> > + kbuf[count - 1] = '\0';
> > +
> > + ret = kstrtoul(kbuf, 10, &threshold);
> > +
> > +out:
> > + kfree(kbuf);
> > + return ret ? ret : count;
> > +}
>
> Still the same comment on this, kmalloc() is not really needed here.
> Capping the size to PAGE_SIZE (usually 4K) is too big. `unsinged long`
> is 64-bit at most, this means the max val is 18446744073709551615
> (20 chars). The lifetime of @kbuf is very short as well, using a stack
> allocated array of chars is fine?
>
> Untested:
>
> static ssize_t write_page_owner_threshold(struct file *file, const char __user *buf,
> size_t count, loff_t *pos)
> {
> char kbuf[21];
> int ret;
>
> count = min_t(size_t, count, sizeof(kbuf));
> if (copy_from_user(kbuf, buf, count))
> return -EFAULT;
>
> kbuf[count - 1] = '\0';
> ret = kstrtoul(kbuf, 10, &threshold);
> return ret ? ret : count;
> }
Isn't there a proc_dointvec counterpart for debugfs?
--
Michal Hocko
SUSE Labs
