Re: [Xen-devel] [PATCH 3/9] xen/pciback: Check if the device is found instead of blindly assuming so.

From: Jan Beulich
Date: Fri Sep 30 2011 - 03:50:14 EST


>>> On 29.09.11 at 21:52, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> wrote:
> Just in case it is not found, don't try to dereference it.
>
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> ---
> drivers/xen/xen-pciback/pci_stub.c | 2 ++
> 1 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/xen/xen-pciback/pci_stub.c
> b/drivers/xen/xen-pciback/pci_stub.c
> index d985b65..55086e9 100644
> --- a/drivers/xen/xen-pciback/pci_stub.c
> +++ b/drivers/xen/xen-pciback/pci_stub.c
> @@ -222,6 +222,8 @@ void pcistub_put_pci_dev(struct pci_dev *dev)
> }
>
> spin_unlock_irqrestore(&pcistub_devices_lock, flags);
> + if (!found_psdev)
> + return;

If this happens, it's a bug (backend controller found the device, but
the generic backend code didn't), so I would say minimally a WARN_ON()
should be issued here.

Jan

>
> /*hold this lock for avoiding breaking link between
> * pcistub and xen_pcibk when AER is in processing




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