Re: [linux-usb-devel] 2.6.6-rc1: cdc-acm still (differently) broken

[Alan Stern]

On Thu, 15 Apr 2004, Colin Leroy wrote:

> Like this one? It works. I'm a bit wondering, however, how comes 
> usb_interface_claimed() returns true, and the check in 
> usb_driver_claim_interface() passes?

While an interface is being probed, usb_interface_claimed() will always
return true for it.  That's because the probing code sets
interface->dev.driver (which is what usb_interface_claimed() tests) before
calling the probe function.  If the probe fails then interface->dev.driver
will be reset.  This all happens inside bus_match() in drivers/base/bus.c.

For the same reason, the test of (dev->driver) in 
usb_driver_claim_interface() -- that is the test you meant, isn't it? -- 
passes (i.e., yields a true value).

Alan Stern

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