Re: [Xen-devel] [PATCH v3 2/7] xen/pciback: Don't deadlock when unbinding.

[David Vrabel <david.vrabel@xxxxxxxxxx>]

On 08/07/14 19:58, konrad@xxxxxxxxxx wrote:
> --- a/drivers/xen/xen-pciback/pci_stub.c
> +++ b/drivers/xen/xen-pciback/pci_stub.c
> @@ -277,10 +277,15 @@ void pcistub_put_pci_dev(struct pci_dev *dev)
>        * (so it's ready for the next domain)
>        */
>  
> -     /* This is OK - we are running from workqueue context
> -      * and want to inhibit the user from fiddling with 'reset'
> +     /* We might be holding the PCI lock (see comment at the top of the
> +      * function) - as such try lock and if we can't then don't worry -
> +      * as either:
> +      *  - we are 'unbind' in which case 'pcistub_device_release' gets
> +      *    called which does the locked version of this.
> +      *  - the toolstack has the smarts to do it and has done the
> +      *    reset on SysFS before assigning this device to another guest.
>        */
> -     pci_reset_function(dev);
> +     pci_try_reset_function(dev);

Why not use __pci_reset_function_locked() and ensure all callers of
pcistub_put_pci_dev() are holding the device lock?

>       pci_restore_state(dev);

If we didn't reset the device there is no need to restore its state.

David

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel