On Thu, 2013-08-22 at 15:34 -0600, Bjorn Helgaas wrote:
> On Mon, Aug 19, 2013 at 2:04 PM, Alex Williamson
> <alex.williamson@xxxxxxxxxx> wrote:
> > We have a pci_walk_bus() interface, but it's exceptionally cumbersome
> > for the callback function to figure out if the device is relevant if
> > the caller is trying to walk all the devices in or below a slot. Add
> > a variant to walk only slot devices.
>
> Is it really exceptionally cumbersome? You can supply the top-level
> slot in the userdata. Can you then use something like this in the
> callback?
>
> bool dev_below_slot(struct pci_dev *dev, struct pci_slot *slot)
> {
> if (!dev)
> return false;
> if (dev->slot == slot)
> return true;
> return dev_below_slot(dev->bus->self, slot);
> }
Maybe I should have said it's ugly and inefficient rather than
cumbersome. This feels like a backwards way to do it, but if you don't
want a walk_slot interface, then it looks like this would work. Thanks,
Alex
> > Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
> > ---
> >
> > This allows me to use pci_walk_bus() and pci_walk_slot() instead of
> > rolling my own for iterating devices for bus/slot reset. Please
> > consider for 3.12 to go with the rest of the bus/slot infrastructure.
> >
> > drivers/pci/bus.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++++++
> > include/linux/pci.h | 2 ++
> > 2 files changed, 58 insertions(+)
> >
> > diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
> > index b1ff02a..316579a 100644
> > --- a/drivers/pci/bus.c
> > +++ b/drivers/pci/bus.c
> > @@ -283,6 +283,62 @@ void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
> > }
> > EXPORT_SYMBOL_GPL(pci_walk_bus);
> >
> > +/** pci_walk_slot - walk devices in/under slot, calling callback.
> > + * @slot slot whose devices should be walked
> > + * @cb callback to be called for each device found
> > + * @userdata arbitrary pointer to be passed to callback.
> > + *
> > + * Walk the given slot, including any bridged devices
> > + * on buses under this slot. Call the provided callback
> > + * on each device found.
> > + *
> > + * We check the return of @cb each time. If it returns anything
> > + * other than 0, we break out.
> > + *
> > + */
> > +void pci_walk_slot(struct pci_slot *slot, int (*cb)(struct pci_dev *, void *),
> > + void *userdata)
> > +{
> > + struct pci_dev *dev;
> > + struct pci_bus *bus;
> > + struct list_head *next;
> > + int retval;
> > +
> > + bus = slot->bus;
> > + down_read(&pci_bus_sem);
> > + next = slot->bus->devices.next;
> > + for (;;) {
> > + if (next == &bus->devices) {
> > + /* end of this bus, go up or finish */
> > + if (bus == slot->bus)
> > + break;
> > + next = bus->self->bus_list.next;
> > + bus = bus->self->bus;
> > + continue;
> > + }
> > + dev = list_entry(next, struct pci_dev, bus_list);
> > +
> > + /* skip anything on the top level bus not in our slot */
> > + if (dev->bus == slot->bus && dev->slot != slot) {
> > + next = dev->bus_list.next;
> > + continue;
> > + }
> > +
> > + if (dev->subordinate) {
> > + /* this is a pci-pci bridge, do its devices next */
> > + next = dev->subordinate->devices.next;
> > + bus = dev->subordinate;
> > + } else
> > + next = dev->bus_list.next;
> > +
> > + retval = cb(dev, userdata);
> > + if (retval)
> > + break;
> > + }
> > + up_read(&pci_bus_sem);
> > +}
> > +EXPORT_SYMBOL_GPL(pci_walk_slot);
> > +
> > struct pci_bus *pci_bus_get(struct pci_bus *bus)
> > {
> > if (bus)
> > diff --git a/include/linux/pci.h b/include/linux/pci.h
> > index daf40cd..cbb291b 100644
> > --- a/include/linux/pci.h
> > +++ b/include/linux/pci.h
> > @@ -1087,6 +1087,8 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
> >
> > void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
> > void *userdata);
> > +void pci_walk_slot(struct pci_slot *slot, int (*cb)(struct pci_dev *, void *),
> > + void *userdata);
> > int pci_cfg_space_size_ext(struct pci_dev *dev);
> > int pci_cfg_space_size(struct pci_dev *dev);
> > unsigned char pci_bus_max_busnr(struct pci_bus *bus);
> >
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