Messages in this thread | | | From | Dmitry Torokhov <> | Subject | Re: patch bus_add_device-losing-an-error-return-from-the-probe-method.patch added to gregkh-2.6 tree | Date | Tue, 4 Apr 2006 21:35:40 -0400 |
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On Tuesday 04 April 2006 17:45, Greg KH wrote: > On Tue, Apr 04, 2006 at 05:28:48PM -0400, Dmitry Torokhov wrote: > > On 4/4/06, Greg KH <gregkh@suse.de> wrote: > > > > > > Hm, no, I unwound this mess, and found the following: > > > > > > - bus_add_device() calls device_attach() > > > - device_attach() calls bus_for_each_drv() for every driver on the bus > > > - bus_for_each_drv() walks all drivers on the bus and calls > > > __device_attach() for every individual driver > > > - __device_attach() calls driver_probe_device() for that driver and device > > > - driver_probe_device() calls down to the probe() function for the > > > driver, passing it that driver, if match() for the bus matches this > > > device. > > > - if that probe() function returns -ENODEV or -ENXIO[1] then the error > > > is ignored and 0 is returned, causing the loop to continue to try > > > more drivers > > > - if the probe() function returns any other error code, it is > > > propagated up, all the way back to bus_add_device. > > > > But why do we do that? probe() failing is driver's problem. The device > > is still there and should still be presented in sysfs. I don't think > > that we should stop if probe() fails - maybe next driver manages to > > bind itself. > > The device is still there. > > Ah, I see what you are saying now. Yeah, we should still add the > default attributes for the bus and create the bus link even if some > random driver had problems. But then, we should still propagate the > error back up, right? >
I don't think so because device creation did not fail. Otherwise how would you as a caller of device_register() distinguish between the following 2 scenarios:
- you got -ENOMEM (or other error code) because device creation indeed failed; - you got -ENOMEM because some odd driver could not allocate 4MB of memory.
IOW you trying to propagate driver error to device creation code...
Also result of device_register() should not depend on whether driver_register() was called earlier or not.
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