Re: [PATCH] irqdomain: remove debugfs_file from struct irq_domain

[Michael Walle]

Am 2021-02-17 22:50, schrieb Marc Zyngier:
> On Wed, 17 Feb 2021 20:10:50 +0000,
> Michael Walle <michael@xxxxxxxx> wrote:
> > Am 2021-02-17 21:02, schrieb Marc Zyngier:
> > > On 2021-02-17 19:57, Michael Walle wrote:
> > >> Hi Greg,
> > >>
> > >>> There's no need to keep around a dentry pointer to a simple file that
> > >>> debugfs itself can look up when we need to remove it from the system.
> > >>> So simplify the code by deleting the variable and cleaning up the
> > >>> logic
> > >>> around the debugfs file.
> > >>
> > >> This will generate the following oops on my board (arm64,
> > >> freescale/fsl-ls1028a-kontron-sl28-var3-ads2.dts). In debugfs_lookup()
> > >> debugfs_mount is NULL.
> > >
> > > That's odd. I gave it a go yesterday, and nothing blew up.
> > > Which makes me wonder whether I had the debug stuff enabled
> > > the first place...
> > >
> > > I've dropped the patch from -next for now until I figure it out
> > > (probably tomorrow).
> >
> > Mh, maybe its my .config, I've attached it. I also noticed that
> > the board boots just fine in our kernel-ci [1].
>
> I reproduced here. I had disabled GENERIC_IRQ_DEBUGFS for obscure
> reasons, and it caught fire as I re-enabled it.
>
> Adding this fixes it for me:
>
> diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
> index 367ff1c35f75..d8a14cf1a7b6 100644
> --- a/kernel/irq/irqdomain.c
> +++ b/kernel/irq/irqdomain.c
> @@ -1904,7 +1904,8 @@ static void debugfs_add_domain_dir(struct 
> irq_domain *d)
>
>  static void debugfs_remove_domain_dir(struct irq_domain *d)
>  {
> -	debugfs_remove(debugfs_lookup(d->name, domain_dir));
> +	if (domain_dir)
> +		debugfs_remove(debugfs_lookup(d->name, domain_dir));
>  }
>
>  void __init irq_domain_debugfs_init(struct dentry *root)
>
>
> Could you please check whether it works for you?

Works for me, too. Thanks.

-michael