Re: [PATCH v4 2/3] x86: pmc_atom: don't check for NULL twice

From: Andy Shevchenko
Date: Fri Nov 28 2014 - 04:49:41 EST


On Wed, 2014-11-19 at 12:36 +0100, Thomas Gleixner wrote:
> On Wed, 12 Nov 2014, Andy Shevchenko wrote:
>
> > debugfs_remove_recursive() is NULL-aware, thus, we may safely remove the check
> > here. There is no need to assing NULL to variable since it will be not used
> > anywhere.

Thanks for review, my comments below.

> >
> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> > Acked-by: Aubrey Li <aubrey.li@xxxxxxxxxxxxxxx>
> > ---
> > arch/x86/kernel/pmc_atom.c | 4 ----
> > 1 file changed, 4 deletions(-)
> >
> > diff --git a/arch/x86/kernel/pmc_atom.c b/arch/x86/kernel/pmc_atom.c
> > index 19b8efa..bcc91ea 100644
> > --- a/arch/x86/kernel/pmc_atom.c
> > +++ b/arch/x86/kernel/pmc_atom.c
> > @@ -202,11 +202,7 @@ static const struct file_operations pmc_sleep_tmr_ops = {
> >
> > static void pmc_dbgfs_unregister(struct pmc_dev *pmc)
> > {
> > - if (!pmc->dbgfs_dir)
> > - return;
> > -
> > debugfs_remove_recursive(pmc->dbgfs_dir);
> > - pmc->dbgfs_dir = NULL;
> > }
>
> So while the patch is correct per se, the whole function is useless.
>
> pmc_dbgfs_register()
>
> dir = debugfs_create_dir("pmc_atom", NULL);
>
> ....
> if (!f)
> goto err;
>
> pmc->dbgfs_dir = dir;
> return 0;
> err:
> pmc_dbgfs_unregister(pmc);
>
> So pmc->dbgfs_dir is always NULL when this is called....

Good catch, I add a new patch to address this.


> Aside of that, if DEBUGFS=n the code keeps pmc->regmap ioremapped for
> no reason.

pmc_hw_reg_setup() uses it. Aubrey, is it intended behaviour?

> Looking deeper:
>
> The pmc_power_off function is installed _BEFORE_ pmc_hw_reg_setup() is
> called, which might not be called if the ioremap fails ....

I don't see any problem here (pmc_power_off uses acpi_base_addr which is
independent to IO mapped space), though Aubrey may shed a light on this.

--
Andy Shevchenko <andriy.shevchenko@xxxxxxxxx>
Intel Finland Oy

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