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PCI: Convert __pci_walk_bus() to be recursive

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The original implementation of __pci_walk_bus() chose a non-recursive walk,
presumably as a precaution on stack use. We do recursive bus walking in
other places though. For example:

  pci_bus_resettable()
  pci_stop_bus_device()
  pci_remove_bus_device()
  pci_bus_allocate_dev_resources()

So recursive pci bus walking is well tested and safe, and is easier to
follow.

Convert __pci_walk_bus() to be recursive to make it easier to introduce
finer grain locking in the future.

Link: https://lore.kernel.org/r/20241022224851.340648-5-kbusch@meta.com
Signed-off-by: Keith Busch <kbusch@kernel.org>
[bhelgaas: commit log]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
This commit is contained in:
Keith Busch 2024-10-22 15:48:50 -07:00 committed by Bjorn Helgaas
parent 4d6dcd6c2f
commit ee061da777
1 changed files with 12 additions and 26 deletions
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38
drivers/pci/bus.c
View File

@ -389,37 +389,23 @@ void pci_bus_add_devices(const struct pci_bus *bus)
}
EXPORT_SYMBOL(pci_bus_add_devices);
static void __pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
void *userdata)
static int __pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
void *userdata)
{
struct pci_dev *dev;
struct pci_bus *bus;
struct list_head *next;
int retval;
int ret = 0;
bus = top;
next = top->devices.next;
for (;;) {
if (next == &bus->devices) {
/* end of this bus, go up or finish */
if (bus == top)
break;
next = bus->self->bus_list.next;
bus = bus->self->bus;
continue;
}
dev = list_entry(next, struct pci_dev, bus_list);
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)
list_for_each_entry(dev, &top->devices, bus_list) {
ret = cb(dev, userdata);
if (ret)
break;
if (dev->subordinate) {
ret = __pci_walk_bus(dev->subordinate, cb, userdata);
if (ret)
break;
}
}
return ret;
}
/**