On Fri, Mar 26, 2021 at 01:53:59PM +0100, Rasmus Villemoes wrote:
> On 26/03/2021 12.38, Peter Zijlstra wrote:
>
> > Implement debugfs_create_str() to easily display names and such in
> > debugfs.
>
> Patches 7-9 don't seem to add any users of this. What's it for precisely?
It's used in patch 7, look close :)
>
> > +
> > +again:
> > + rcu_read_lock();
> > + str = rcu_dereference(*(char **)file->private_data);
> > + len = strlen(str) + 1;
> > +
> > + if (!copy || copy_len < len) {
> > + rcu_read_unlock();
> > + kfree(copy);
> > + copy = kmalloc(len + 1, GFP_KERNEL);
> > + if (!copy) {
> > + debugfs_file_put(dentry);
> > + return -ENOMEM;
> > + }
> > + copy_len = len;
> > + goto again;
> > + }
> > +
> > + strncpy(copy, str, len);
> > + copy[len] = '\n';
> > + copy[len+1] = '\0';
> > + rcu_read_unlock();
>
> As noted (accidentally off-list), this is broken. I think you want this
> on top
>
> - len = strlen(str) + 1;
> + len = strlen(str);
>
> - strncpy(copy, str, len);
> + memcpy(copy, str, len);
> copy[len] = '\n';
> - copy[len+1] = '\0';
>
> > +EXPORT_SYMBOL_GPL(debugfs_read_file_str);
>
> Why?
Because there is a user of it? Yes, it's not in a module, but to make
it easy, might as well export it now.
thanks,
greg k-h
