On 06/18/2013 04:18 AM, Bjorn Helgaas wrote:
> On Sun, May 26, 2013 at 11:53:12PM +0800, Jiang Liu wrote:
>> Enhance EDAC drviers to use hotplug-safe iterators to walk PCI buses.
>>
>> Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxx>
>> Cc: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
>> Cc: Doug Thompson <dougthompson@xxxxxxxxxxxx> r
>> Cc: linux-edac@xxxxxxxxxxxxxxx
>> Cc: linux-kernel@xxxxxxxxxxxxxxx
>> ---
>> drivers/edac/i7core_edac.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/edac/i7core_edac.c b/drivers/edac/i7core_edac.c
>> index 0ec3e95..7146e10 100644
>> --- a/drivers/edac/i7core_edac.c
>> +++ b/drivers/edac/i7core_edac.c
>> @@ -1296,7 +1296,7 @@ static unsigned i7core_pci_lastbus(void)
>> int last_bus = 0, bus;
>> struct pci_bus *b = NULL;
>>
>> - while ((b = pci_find_next_bus(b)) != NULL) {
>> + for_each_pci_root_bus(b) {
>
> This doesn't look equivalent. Previously, we iterated over all PCI
> buses, so we returned the highest bus number seen anywhere. Now we
> only look at root buses, so we return the highest bus number of any
> root bus. But if that root bus has a bridge on it, obviously the
> bus on the other side has a higher number.
Hi Bjorn,
I think the name pci_find_next_bus() is misleading, it should be named
pci_find_next_root_bus() actually because it returns next root bus indeed.
>
> Even with that fix, a hot-add at the same time i7core_probe() runs
> could mean an incorrect result. This is all very i7 topology-dependent,
> so I don't think the PCI core can do anything more than avoid oopses
> from traversing lists incorrectly.
Yeah, it's very architecture specific. I think i7core_edac assume no PCI
root bus hotplug on i7 platforms because it's desktop or mobile processors.
>
> Bjorn
>
>> bus = b->number;
>> edac_dbg(0, "Found bus %d\n", bus);
>> if (bus > last_bus)
>> --
>> 1.8.1.2
>>
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