linux-kernel - Re: [PATCH 3/6] PCI: introduce pci_trim_stale

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Date:	Tue, 25 Jun 2013 20:56:25 +0300 (EEST)
From:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:	Andy Shevchenko <andy.shevchenko@...il.com>
Cc:	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Yinghai Lu <yinghai@...nel.org>, john.ronciak@...el.com,
	miles.j.penner@...el.com, bruce.w.allan@...el.com,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-pci@...r.kernel.org, x86@...nel.org
Subject: Re: [PATCH 3/6] PCI: introduce pci_trim_stale_devices()

Andy Shevchenko wrote:
> On Tue, Jun 25, 2013 at 7:22 PM, Mika Westerberg
> <mika.westerberg@...ux.intel.com> wrote:
> 
> > The new function stops and removes the device if it doesn't respond.
> > If the device responds and it's a bus we apply the function to all
> > subdevices recursively.
> >
> > It's useful for hotplug bus check case, when you need drop all unplugged
> > devices before looking for new ones.
> 
> One comment below.
> 
> > +void pci_trim_stale_devices(struct pci_dev *dev)
> > +{
> > +       struct pci_bus *bus = dev->subordinate;
> > +       struct pci_dev *child, *tmp;
> > +       bool alive;
> > +       u32 l;
> > +
> > +       /* check if the device responds */
> > +       alive = pci_bus_read_dev_vendor_id(dev->bus, dev->devfn, &l, 0);
> > +       if (!alive)
> > +               pci_stop_and_remove_bus_device(dev);
> > +
> > +       if (alive && bus)
> > +               list_for_each_entry_safe(child, tmp, &bus->devices, bus_list)
> > +                       pci_trim_stale_devices(child);
> 
> It's not a tail call anyway, so, what about
> 
>    if (!pci_bus_read_dev_vendor_id(dev->bus, dev->devfn, &l, 0)) {
>              pci_stop_and_remove_bus_device(dev);
>    } else if (bus) {
>              list_for_each_entry_safe(child, tmp, &bus->devices, bus_list)
>                      pci_trim_stale_devices(child);
>    }

Why? It looks uglier.


-- 
 Kirill A. Shutemov
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