Re: [libvirt] [PATCH] udev: only report a warning if udev_enumerate_scan_devices fails

On 2/13/19 7:38 AM, Marc Hartmayer wrote: > Even if an error is reported by `udev_enumerate_scan_devices`, > e.g. because a driver of a device has an bug, we can still enumerate > all other devices. Additionally the documentation of > udev_enumerate_scan_devices says that on success an integer >= 0 is > returned (see man udev_enumerate_scan_devices(3)). > > Reviewed-by: Bjoern Walk <bwalk(a)linux.ibm.com&gt; > Signed-off-by: Marc Hartmayer <mhartmay(a)linux.ibm.com&gt; > --- > src/node_device/node_device_udev.c | 9 ++------- > 1 file changed, 2 insertions(+), 7 deletions(-) > Interesting - looking at many examples of udev_enumerate_scan_devices usage shows a lack of testing the return value and as is done here just using @udev_enumerate to add devices after the call. Eventually found some source code for enumerator_scan_devices_tags which I believe is what device_enumerator_scan_devices would call due to what our AddMatches does. It seems that code works until it finds an error, but still would return a partially enumerated list.

Long way of saying I think this is fine... However, now @ret = -1 doesn't ever get changed, so the caller would still fail. So it's a nice way to test your other patch ;-)

> diff --git a/src/node_device/node_device_udev.c b/src/node_device/node_device_udev.c > index 299f55260129..90168eb8a969 100644 > --- a/src/node_device/node_device_udev.c > +++ b/src/node_device/node_device_udev.c > @@ -1480,13 +1480,8 @@ udevEnumerateDevices(struct udev *udev) > if (udevEnumerateAddMatches(udev_enumerate) < 0) > goto cleanup; > > - ret = udev_enumerate_scan_devices(udev_enumerate); > - if (ret != 0) { > - virReportError(VIR_ERR_INTERNAL_ERROR, > - _("udev scan devices returned %d"), > - ret); > - goto cleanup; > - } > + if (udev_enumerate_scan_devices(udev_enumerate) < 0) > + VIR_WARN("udev scan devices failed"); Either before or after this, set ret = 0... or change the default from -1 to 0 and only change if the AddMatches fails.

I think the other patch would still be necessary since if udevEnumerateAddMatches fails, then wouldn't the issue of setting threadQuit still exist? > > udev_list_entry_foreach(list_entry, > udev_enumerate_get_list_entry(udev_enumerate)) { > BTW: Using udevProcessDeviceListEntry as the 'example' of not failing if an element of udev_enumerate is problematic, I think logically if we don't get a full list we'd be OK to continue as well.

John