On Fri, Dec 28, 2007 at 03:03:22PM -0800, Andrew Morton wrote:
> On Fri, 28 Dec 2007 13:11:37 +0000 "Bahadir Balban" <[email protected]> wrote:
>
> > Hi,
> >
> > On ARM with PCI, I get this error since -rc2 (didn't try rc1):
> >
> > sysfs: duplicate filename 'bridge' can not be created
> > WARNING: at fs/sysfs/dir.c:424 sysfs_add_one()
> > [<c00287fc>] (dump_stack+0x0/0x14) from [<c00cbc64>] (sysfs_add_one+0x50/0xf4)
> > [<c00cbc14>] (sysfs_add_one+0x0/0xf4) from [<c00ccd30>]
> > (sysfs_create_link+0xec/0x184)
> > r6:cfca8b48 r5:cfca96c8 r4:cfc2fec0
> > [<c00ccc44>] (sysfs_create_link+0x0/0x184) from [<c0160b44>]
> > (pci_bus_add_devices+0xf0/0x144)
> > r7:cfc5a2d4 r6:cfc5a2d4 r5:cfc5a2c0 r4:cfcad800
> > [<c0160a54>] (pci_bus_add_devices+0x0/0x144) from [<c0160b30>]
> > (pci_bus_add_devices+0xdc/0x144)
> > r7:cfc5a3d4 r6:cfc5a3d4 r5:cfc5a3c0 r4:cfcadc00
> > [<c0160a54>] (pci_bus_add_devices+0x0/0x144) from [<c0160b30>]
> > (pci_bus_add_devices+0xdc/0x144)
> > r7:cfc5a4d4 r6:cfc5a4d4 r5:cfc5a4c0 r4:cfc5d400
> > [<c0160a54>] (pci_bus_add_devices+0x0/0x144) from [<c000a934>]
> > (pci_common_init+0x148/0x184)
> > r7:c035fd58 r6:cfc3e760 r5:c001e030 r4:cfc5a4c0
> >
> >
> > Any idea why?
> >
>
> (suitable cc added)
Looks to me as if the code added to pci_bus_add_devices() is off it's
rocker.
In brief, pci_bus_add_devices() is supposed to be callable given *any*
state of the bus, and it will add any new devices found in the bus tree
from the bus that it's called for downwards. (That's how I designed
that bit of PCI code - so it can cope with hotpluggable PCI bridges.)
It still does this. However, some bright spark decided to add sysfs
links to it - and break it. Now, whenever we descend into a subordinate
bus (and return to a higher level) we will try to create a sysfs symlink
even if the bus is one that we already registered.
So... that sysfs_create_link() call in there should not be unconditional.
It should _only_ ever do that call if list_empty(&dev->subordinate->node)
was true. IOW, we only create symlinks for subordinate bus that we don't
already know about.
It looks like it was introduced by Greg's "PCI: fix __must_check warnings"
but why a patch advertised _solely_ as a fix is adding additional sysfs
attributes I've no idea.
Something like the following should fix it. Bahadir - please test.
diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
index 9e5ea07..132a91f 100644
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -131,18 +131,21 @@ void pci_bus_add_devices(struct pci_bus *bus)
* it and then scan for unattached PCI devices.
*/
if (dev->subordinate) {
- if (list_empty(&dev->subordinate->node)) {
+ int new_bus = list_empty(&dev->subordinate->node);
+ if (new_bus) {
down_write(&pci_bus_sem);
list_add_tail(&dev->subordinate->node,
&dev->bus->children);
up_write(&pci_bus_sem);
}
pci_bus_add_devices(dev->subordinate);
- retval = sysfs_create_link(&dev->subordinate->class_dev.kobj,
- &dev->dev.kobj, "bridge");
- if (retval)
- dev_err(&dev->dev, "Error creating sysfs "
- "bridge symlink, continuing...\n");
+ if (new_bus) {
+ retval = sysfs_create_link(&dev->subordinate->class_dev.kobj,
+ &dev->dev.kobj, "bridge");
+ if (retval)
+ dev_err(&dev->dev, "Error creating sysfs "
+ "bridge symlink, continuing...\n");
+ }
}
}
}
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