On Sun, 18.01.15 04:21, Ivan Shapovalov (intelfx...@gmail.com) wrote: > Hi folks, > > I'm trying to fix this bug: > https://bugs.freedesktop.org/show_bug.cgi?id=88401 > > The initial problem (as reported) looks following: performing a reload > (maybe implicitly) re-starts alsa-restore.service if it is enabled. > > With a bit of debugging I've apparently found a root cause. Explanation > following. > > Suppose we have CUPS installed and org.cups.cupsd.{path,service} are > started. > > We enter manager_reload(), units are serialized, reset, re-read, > deserialized and then cold-plugged. (Note that e. g. unit_notify() has > special "protection" to avoid spawning jobs when a reload is in > progress.) > > So, if org.cups.cupsd.path is started, *it is almost first to be > cold-plugged*. The call chain is: > > unit_coldplug() > path_coldplug() > path_enter_waiting() // recheck == true > path_check_good() // returns true > path_enter_running() > manager_add_job() // at this point we're fucked up > > So, a job is enqueued for org.cups.cupsd.service. This is already wrong, > because a reload should never enqueue any jobs (IIUC). So, the job is > enqueued... remember that almost all units are inactive by now. Thus we > end up re-starting half a system (the whole basic.target) as > dependencies. > > Questions: > - is my analysis correct? > - if yes, then how to fix this? Maybe add a similar > "if (UNIT(p)->manager->n_reloading <= 0)" check to > path_enter_running() to avoid calling manager_add_job() during > reloading?
Hmm, how does this relate to the ALSA case? I mean, the alsa units don't use .path units, do they? So, in general I think .path units should trigger things on reload, but only those things that ar bound to "level", not those to "edge", if you follow what I mean. More specifically, I think that cups.path should trigger things, since its job is to make sure that cups.service is running as long as there's a file in /var/spool/cups/. PathExists=/PathExistsGlob=/DirectoryNotEmpty= are all of the "level" kind. As long as the condition they express is true they should ensure their service is running. PathChanged= and PathModified= OTOH are "edge" triggers, and they should only trigger something when a file is changed while we look at it, but not during coldplugging. During a reload, I hence believe it is OK if trigger units trigger new jobs. Anyway, I am not really sure I grok the relation to alsa-restore... Can you elaborate? Lennart -- Lennart Poettering, Red Hat _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
