On Tue, Oct 16, 2007 at 10:55:54AM -0400, Alan Stern wrote:
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> On Tue, 16 Oct 2007, Dave Young wrote:
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> > > I finally duplicated this on one of my machines here at boot time, wi=
th
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> > > USB built into the kernel.  I'll work tomorrow on tracking this down
> > > further...
> > Hi,
> > I add some printk messages, dump_stack and some others, here is the
> > dmesg dump with debug info(lines begin with "hidave"):
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> Okay, good, the extra printk messages show exactly where the problem=20
> lies.
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> In usb_set_configuration(), each new interfaces is registered and then
> usb_create_sysfs_intf_files() gets called for that interface.  This
> makes sense, because obviously we can't create sysfs files for an
> interface before it is registered.
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> The problem is that during registration drivers get probed, and drivers=
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> sometimes call usb_set_interface() from their probe method.  This=20
> routine also calls usb_create_sysfs_intf_files(), and the result is=20
> that the sysfs files get created twice:
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> 	First by usb_set_interface, from the driver probe;
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> 	Then by usb_set_configuration, when registration is
> 	finished.
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> I can think of two possible ways around the problem.  One is to add a=20
> bit to the usb_interface structure, recording whether the sysfs files=20
> have been created.  The other is always to remove the files just before=
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> trying to create them.

I haven't looked at this code at all, but neither approach feels right to
me.

How does this work at all?  Even if you load a driver later, wouldn't it
call usb_set_interface(), which would call usb_create_sysfs_intf_files()
and hit the same issue?

Heck, why do both call usb_create_sysfs_intf_file()?  I would guess if
you're *changing* the active configuration you would need to do that, but
why in usb_set_interface() at all?

Matt

--=20
Matthew Dharm                              Home: mdharm-usb@one-eyed-alien.=
net=20
Maintainer, Linux USB Mass Storage Driver

I say, what are all those naked people doing?
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User Friendly, 12/14/1997