Re: [PATCH] libxl: do not try to detach pci device when none attached

[Marek Marczykowski <marmarek@mimuw.edu.pl>]

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On 10.06.2011 13:03, Stefano Stabellini wrote:
> On Fri, 10 Jun 2011, Marek Marczykowski wrote:
>> On 10.06.2011 12:44, Stefano Stabellini wrote:
>>> On Fri, 10 Jun 2011, Marek Marczykowski wrote:
>>>> # HG changeset patch
>>>> # User Marek Marczykowski <marmarek@mimuw.edu.pl>
>>>> # Date 1307662302 -7200
>>>> # Node ID 88f67b423c89f4bd604837b9eae2483dad5ebb0d
>>>> # Parent  4b392511ae0840fba66c40aa2788dc1ff402b6e8
>>>> libxl: do not try to detach pci device when none attached
>>>>
>>>> Fixes SEGV on domain destroy
>>>>
>>>> Signed-off-by: Marek Marczykowski <marmarek@mimuw.edu.pl>
>>>>
>>>> diff --git a/tools/libxl/libxl_pci.c b/tools/libxl/libxl_pci.c
>>>> --- a/tools/libxl/libxl_pci.c
>>>> +++ b/tools/libxl/libxl_pci.c
>>>> @@ -1039,6 +1039,8 @@ int libxl_device_pci_shutdown(libxl_ctx 
>>>>      rc = libxl_device_pci_list_assigned(ctx, &pcidevs, domid, &num);
>>>>      if ( rc )
>>>>          return rc;
>>>> +    if ( num == 0 )
>>>> +        return 0;
>>>>      for (i = 0; i < num; i++) {
>>>>          /* Force remove on shutdown since, on HVM, qemu will not always
>>>>           * respond to SCI interrupt because the guest kernel has shut down the
>>>
>>> Is the problem here that num is 0 and pcidevs is uninitialized?
>>> If so, would this patch solve the problem you are seeing?
>>
>> No, when there is no PCI devs, libxl_device_pci_list_assigned exists
>> earlier - before allocating memory for pcidevs.
> 
> Sorry, but I still don't understand.
> 
> If num is 0, it won't enter the following loop anyway, the only
> other operation in libxl_device_pci_shutdown is free(pcidevs) and
> pcidevs should be NULL so nothing bad should happen.

Ah, ok. So your patch should also works.

-- 
Pozdrawiam / Best Regards,
Marek Marczykowski         | RLU #390519
marmarek at mimuw edu pl   | xmpp:marmarek at staszic waw pl


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