[libvirt] [PATCH] node_device: Check return value for udev_new()

[Boris Fiuczynski]

On 12/08/2016 01:48 PM, Martin Kletzander wrote:
> On Thu, Dec 01, 2016 at 01:52:03PM +0100, Marc Hartmayer wrote:
>> On Wed, Nov 30, 2016 at 04:25 PM +0100, Martin Kletzander
>> <mkletzan at redhat.com> wrote:
>>> On Wed, Nov 30, 2016 at 01:45:32PM +0100, Marc Hartmayer wrote:
>>>> The comment was actually wrong as
>>>> https://www.freedesktop.org/software/systemd/man/udev_new.html
>>>> mentions that on failure NULL is returned.
>>>>
>>>> Signed-off-by: Marc Hartmayer <mhartmay at linux.vnet.ibm.com>
>>>> Reviewed-by: Bjoern Walk <bwalk at linux.vnet.ibm.com>
>>>> Reviewed-by: Boris Fiuczynski <fiuczy at linux.vnet.ibm.com>
>>>> ---
>>>> src/node_device/node_device_udev.c | 10 ++++------
>>>> 1 file changed, 4 insertions(+), 6 deletions(-)
>>>>
>>>> diff --git a/src/node_device/node_device_udev.c
>>>> b/src/node_device/node_device_udev.c
>>>> index 4b81312..4b0a875 100644
>>>> --- a/src/node_device/node_device_udev.c
>>>> +++ b/src/node_device/node_device_udev.c
>>>> @@ -1491,13 +1491,11 @@ static int nodeStateInitialize(bool privileged,
>>>>     if (udevPCITranslateInit(privileged) < 0)
>>>>         goto cleanup;
>>>>
>>>> -    /*
>>>> -     *
>>>> http://www.kernel.org/pub/linux/utils/kernel/hotplug/libudev/libudev-udev.html#udev-new
>>>>
>>>> -     *
>>>> -     * indicates no return value other than success, so we don't check
>>>> -     * its return value.
>>>> -     */
>>>>     udev = udev_new();
>>>> +    if (!udev) {
>>>> +        virReportOOMError();
>>>> +        goto cleanup;
>>>> +    }
>>>
>>> Is that true for other udevs and not just systemd-udev?
>>
>> I'm not sure about other versions of udev but the NULL pointer is already
>> handled in udevStatInitialize() for udev_new() in a likewise manner.
>>
>>> Does it really mean just an OOM error?
>>
>> It fails for systemd-udev if malloc/calloc fails => this is most
>> likely a OOM error at this point.
>>
>>> Couldn't we add a proper error message?
>>
>> In udevStateInitialize() the error handling reports an internal error
>> but as the original error is caused by OOM I think we have to use
>> virReportOOMError().
>>
>
> OK, it doesn't make sense for it to return NULL anyway, so I'm OK with
> that, but I'd rather use internal error as we're not completely sure all
> udev implementations can fail only due to not enough memory.  Plus the
> internal error will give more information in the logs.
>
> Martin
Shouldn't the OOM error method already to be used if only one udev 
implementation could fail due to not enough memory?

>
>>
>> --
>> Beste Grüße / Kind regards
>>   Marc Hartmayer
>>
>> IBM Deutschland Research & Development GmbH
>> Vorsitzende des Aufsichtsrats: Martina Koederitz
>> Geschäftsführung: Dirk Wittkopp
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>>
>
>
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-- 
Mit freundlichen Grüßen/Kind regards
    Boris Fiuczynski

IBM Deutschland Research & Development GmbH
Vorsitzender des Aufsichtsrats: Martina Köderitz
Geschäftsführung: Dirk Wittkopp
Sitz der Gesellschaft: Böblingen
Registergericht: Amtsgericht Stuttgart, HRB 243294