On Fri, Apr 09, 2010 at 07:13:24PM +0900, Isaku Yamahata wrote:
> When looking down child bus, it looked parent bridge's
> bus number.
> It should look child bridge's.
>
> Cc: Blue Swirl <blauwir...@gmail.com>
> Cc: "Michael S. Tsirkin" <m...@redhat.com>
> Signed-off-by: Isaku Yamahata <yamah...@valinux.co.jp>
> ---
> hw/pci.c | 4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/hw/pci.c b/hw/pci.c
> index 0dbca17..2f6907b 100644
> --- a/hw/pci.c
> +++ b/hw/pci.c
> @@ -1557,9 +1557,9 @@ PCIBus *pci_find_bus(PCIBus *bus, int bus_num)
>
> /* try child bus */
> QLIST_FOREACH(sec, &bus->child, sibling) {
> - if (!bus->parent_dev /* pci host bridge */
> + if (!sec->parent_dev /* pci host bridge */
I don't understand this first test. As far as I can tell
secondary bus must always have a device, as set by
pci_register_secondary_bus. Should this
rather be assert(sec->parent_dev)?
> || (pci_bus_num(sec) <= bus_num &&
And so the above should just use
sec->parent_dev->config[PCI_SECONDARY_BUS]
instead of a wrapper that tests sec->parent_dev.
> - bus_num <= bus->parent_dev->config[PCI_SUBORDINATE_BUS]) ) {
> + bus_num <= sec->parent_dev->config[PCI_SUBORDINATE_BUS]) ) {
> ret = pci_find_bus(sec, bus_num);
> if (ret) {
I think that in the above, we can just as well do
return pci_find_bus() - if multiple children claim
the same bus range, on real hardware only one
of them will claim the transaction.
> return ret;
I find the use of recursion here confusing.
Since as pointed out above this can be a tail recursion,
it can easily be converted to a loop.
How does the below look, for example?
Note: completely untested, likely broken:
diff --git a/hw/pci.c b/hw/pci.c
index b6abd67..e9d6def 100644
--- a/hw/pci.c
+++ b/hw/pci.c
@@ -1546,26 +1546,33 @@ static void pci_bridge_write_config(PCIDevice *d,
PCIBus *pci_find_bus(PCIBus *bus, int bus_num)
{
- PCIBus *sec, *ret;
+ PCIBus *sec;
+ bool found;
- if (!bus)
+ if (!bus) {
return NULL;
+ }
if (pci_bus_num(bus) == bus_num) {
return bus;
}
/* try child bus */
- QLIST_FOREACH(sec, &bus->child, sibling) {
- if (!bus->parent_dev /* pci host bridge */
- || (pci_bus_num(sec) <= bus_num &&
- bus_num <= bus->parent_dev->config[PCI_SUBORDINATE_BUS]) ) {
- ret = pci_find_bus(sec, bus_num);
- if (ret) {
- return ret;
+ do {
+ found = false;
+ QLIST_FOREACH(sec, &bus->child, sibling) {
+ assert(sec->parent_dev);
+ if (sec->parent_dev->config[PCI_SECONDARY_BUS] == bus_num) {
+ return sec;
+ }
+ if (sec->parent_dev->config[PCI_SECONDARY_BUS] < bus_num &&
+ bus_num <= sec->parent_dev->config[PCI_SUBORDINATE_BUS]) {
+ bus = sec;
+ found = true;
+ break;
}
}
- }
+ } while (found);
return NULL;
}
> --
> 1.6.6.1
>
