Patchwork [3/6] PCI: introduce pci_trim_stale_devices()

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Submitter Mika Westerberg
Date June 25, 2013, 4:22 p.m.
Message ID <1372177330-28013-4-git-send-email-mika.westerberg@linux.intel.com>
Download mbox | patch
Permalink /patch/254232/
State Superseded
Headers show

Comments

Mika Westerberg - June 25, 2013, 4:22 p.m.
From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>

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.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
 drivers/pci/remove.c | 20 ++++++++++++++++++++
 include/linux/pci.h  |  1 +
 2 files changed, 21 insertions(+)
Andy Shevchenko - June 25, 2013, 5:47 p.m.
On Tue, Jun 25, 2013 at 7:22 PM, Mika Westerberg
<mika.westerberg@linux.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);
   }

> +}

--
With Best Regards,
Andy Shevchenko
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Kirill A. Shutemov - June 25, 2013, 5:56 p.m.
Andy Shevchenko wrote:
> On Tue, Jun 25, 2013 at 7:22 PM, Mika Westerberg
> <mika.westerberg@linux.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.
Rafael J. Wysocki - June 28, 2013, 7:59 p.m.
On Tuesday, June 25, 2013 07:22:07 PM Mika Westerberg wrote:
> From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
> 
> 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.
> 
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

I think it'd be better to fold this into [4/6].  This way it would be clearer
what that patch did.

Thanks,
Rafael


> ---
>  drivers/pci/remove.c | 20 ++++++++++++++++++++
>  include/linux/pci.h  |  1 +
>  2 files changed, 21 insertions(+)
> 
> diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c
> index 8fc54b7..77b7a64 100644
> --- a/drivers/pci/remove.c
> +++ b/drivers/pci/remove.c
> @@ -112,6 +112,26 @@ void pci_stop_and_remove_bus_device(struct pci_dev *dev)
>  }
>  EXPORT_SYMBOL(pci_stop_and_remove_bus_device);
>  
> +/**
> + * pci_trim_stale_devices - remove stale device or any stale child
> + */
> +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);
> +}
> +
>  void pci_stop_root_bus(struct pci_bus *bus)
>  {
>  	struct pci_dev *child, *tmp;
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 3a24e4f..8f6e7a0 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -754,6 +754,7 @@ struct pci_dev *pci_dev_get(struct pci_dev *dev);
>  void pci_dev_put(struct pci_dev *dev);
>  void pci_remove_bus(struct pci_bus *b);
>  void pci_stop_and_remove_bus_device(struct pci_dev *dev);
> +void pci_trim_stale_devices(struct pci_dev *dev);
>  void pci_stop_root_bus(struct pci_bus *bus);
>  void pci_remove_root_bus(struct pci_bus *bus);
>  void pci_setup_cardbus(struct pci_bus *bus);
>

Patch

diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c
index 8fc54b7..77b7a64 100644
--- a/drivers/pci/remove.c
+++ b/drivers/pci/remove.c
@@ -112,6 +112,26 @@  void pci_stop_and_remove_bus_device(struct pci_dev *dev)
 }
 EXPORT_SYMBOL(pci_stop_and_remove_bus_device);
 
+/**
+ * pci_trim_stale_devices - remove stale device or any stale child
+ */
+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);
+}
+
 void pci_stop_root_bus(struct pci_bus *bus)
 {
 	struct pci_dev *child, *tmp;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 3a24e4f..8f6e7a0 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -754,6 +754,7 @@  struct pci_dev *pci_dev_get(struct pci_dev *dev);
 void pci_dev_put(struct pci_dev *dev);
 void pci_remove_bus(struct pci_bus *b);
 void pci_stop_and_remove_bus_device(struct pci_dev *dev);
+void pci_trim_stale_devices(struct pci_dev *dev);
 void pci_stop_root_bus(struct pci_bus *bus);
 void pci_remove_root_bus(struct pci_bus *bus);
 void pci_setup_cardbus(struct pci_bus *bus);