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    SubjectRe: patch bus_add_device-losing-an-error-return-from-the-probe-method.patch added to gregkh-2.6 tree
    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.

    > - if the probe() function returns 0, the device is bound to the driver,
    > and it returns 0. Hm, looks like we continue to loop here too, we
    > could probably stop now that we have bound a driver to the device.
    >

    Could it be that logic is simply reversed?

    > So, I'm pretty sure that this is safe and should work just fine. To be
    > sure, let me go reboot my box with this change on it after I finish this
    > email :)
    >
    > Does that help?
    >
    > thanks,
    >
    > greg k-h
    >
    > [1] - stupid agp drivers (or some other video drivers) require this. I
    > need to go fix them up so they don't do this, if they haven't been
    > fixed already...
    >


    --
    Dmitry
    -
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