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

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(a)redhat.com&gt; 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(a)linux.vnet.ibm.com&gt; >>>Reviewed-by: Bjoern Walk <bwalk(a)linux.vnet.ibm.com&gt; >>>Reviewed-by: Boris Fiuczynski <fiuczy(a)linux.vnet.ibm.com&gt; >>>--- >>> 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... >>>- * >>>- * 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