Am So., 23. Dez. 2018 um 19:09 Uhr schrieb Dmitry Torokhov <dmitry.torok...@gmail.com>:
[ also added Linus to CC on that one too ] > > On Sun, Dec 23, 2018 at 06:17:04PM +0100, Christian Brauner wrote: > > On Sun, Dec 23, 2018 at 05:49:54PM +0100, Marcus Meissner wrote: > > > Hi, > > > > > > I am the maintainer of libmtp and libgphoto2 > > > > > > Some months ago I was made aware of this bug: > > > https://bugs.kde.org/show_bug.cgi?id=387454 > > > > > > This was fallout identified to come from this kernel commit: > > > > > > commit 1455cf8dbfd06aa7651dcfccbadb7a093944ca65 > > > Author: Dmitry Torokhov <dmitry.torok...@gmail.com> > > > Date: Wed Jul 19 17:24:30 2017 -0700 > > > > Fwiw, the addition of {un}bind events has caused issues for > > systemd-udevd as well and is tracked here: > > https://github.com/systemd/systemd/issues/7587 > > I haven't been aware of this until yesterday and it seems that so far > > this hasn't been brought up on lkml until you did now. > > The fallout was caused by premature enabling of the new events in > systemd/udev by yours truly (even though the commit has Lennart's name > on it due to how it was merged): > > https://github.com/systemd/systemd/commit/9a39e1ce314d1a6f8a754f6dab040019239666a9 > > "Add handling for bind/unbind actions (#6720) > > Newer kernels will emit uevents with "bind" and "unbind" actions. These > uevents will be issued when driver is bound to or unbound from a device. > "Bind" events are helpful when device requires a firmware to operate > properly, and driver is unable to create a child device before firmware > is properly loaded. > > For some reason systemd validates actions and drops the ones it does not > know, instead of passing them on through as old udev did, so we need to > explicitly teach it about them." > > Similarly it is now papered over in systemd/udev until we make it > properly handle new events: > > https://github.com/systemd/systemd/commit/56c886dc7ed5b2bb0882ba85136f4070545bfc1b > > "sd-device: ignore bind/unbind events for now > > Until systemd/udev are ready for the new events and do not flush entire > device state on each new event received, we should ignore them." > And how about peoples still uses systemd < 235 and newer kernels ? > > > > > > If distributions would be using libmtp and libgphoto2 udev rules > > > that just triggered on "add" events, and not the new "bind" events, > > > the missing "attribute tagging" of the "bind" events would confused the > > > KDE Solid device detection and make the devices no longer detected. > > > > > > This did not affect distributions that rely on the newer "hwdb" > > > device detection method. > > > > > > I have released fixed libmtp and libgphoto2 versions in November, so > > > this is under control, but wanted to bring this up as a "kernel caused > > > userland breakage". > > Given that we explicitly enabled these new events in systemd/udev code > this is actually "userspace caused userspace breakage" case. I really do not agree with you here .. Is kernel -> userspace breakage and while userspace is trying to workaround even much more breaks. > > Still it is unfortunate that we did nit notice that my patch enabling > this functionality in systemd was premature. > > Thanks. > > -- > Dmitry BR, Gabriel