Re: [PATCH] Inform users about busy device assignment attempt

[Alexander Graf <agraf@suse.de>]

Daniel P. Berrange wrote:
> On Wed, Dec 09, 2009 at 07:04:13PM +0100, Alexander Graf wrote:
>   
>> When using -pcidevice on a device that is already in use by a kernel driver
>> all the user gets is the following (very useful) information:
>>
>>   Failed to assign device "04:00.0" : Device or resource busy
>>   Failed to deassign device "04:00.0" : Invalid argument
>>   Error initializing device pci-assign
>>
>> Since I usually prefer to have my computer do the thinking for me, I figured
>> it might be a good idea to check and see if a device is actually used by a
>> driver. If so, tell the user.
>>
>> So with this patch applied you get the following output:
>>
>>   Failed to assign device "04:00.0" : Device or resource busy
>>   *** The driver 'igb' is occupying your device 04:00.0.
>>   *** Try running "rmmod igb" on the commandline
>>   Failed to deassign device "04:00.0" : Invalid argument
>>   Error initializing device pci-assign
>>
>> That should keep people like me from doing the most obvious misuses :-).
>>     
>
> Unconditionally telling people to run rmmod is a pretty dangerous thing
> todo. If they typod and gave the PCI addr of their disk controller instead
> of the NIC, they'll be less than happy at the results of our recommended
> command to "fix" the error. Likewise if they have multiple devices using
> the same driver & just want to assign one of them. I think it is safer to
> just have the first bit of your proposed error message
>
>   "The device 04:00.0 is in use by the kernel driver 'igb'."
>
>
> NB 'rmmod' is not the ideal approach for PCI assignment. It is better
> to explicitly re-bind the device to 'pcistub' because that ensures that
> no other driver will ever be able to reclaim the device.
>   

Oh - mind to get into detail there? It'd be great if we could tell users
an even better way to unbind their device from the driver than rmmod :)

Alex