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

[Marc Hartmayer]

On Thu, Dec 08, 2016 at 01:48 PM +0100, Martin Kletzander <mkletzan at redhat.com> 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

Polite ping :) And is the internal error still working if we have a OOM?


--
Beste Grüße / Kind regards
   Marc Hartmayer

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