On Mon, Oct 27, 2014 at 06:37:21PM +0100, Lennart Poettering wrote: > On Sun, 26.10.14 05:37, Zbigniew Jędrzejewski-Szmek (zbys...@in.waw.pl) wrote: > > > https://bugs.freedesktop.org/show_bug.cgi?id=73942 > > So in really old systemd versions I had a concept in place of never > printing to the console if there was a controlling process on it. The > kernel's concept of a controlling process we used as a somewhat > natural synchronization on the tty. However, this functionality has > pretty much been lost. > > I am not entirely sure what happened between all the reworks there, > but maybe we should just resurrect that scheme? Suppressing output on > the console if there's a controlling process would not just > automatically avoid mixing password queries with getty login prompts, > but also all other cases where some process wants exclusive ownership > of the tty. > > Using the controlling tty for this would be somewhat nice, as all > users of the tty would just work with it. Another idea could be to use > BSD locks on the /dev/console device node. Everybody with access on > the tty could take one of the logs. We would even have R/W locks then, > where the status output would just take a read lock, while things like > gettys and the password stuff would take a full write lock. I don't get this r/w distinction. In either case access has to be exclusive.
> Either solution appears nicer to me then explicitly hooking up PID 1 > with the ask-password stuff, in particularly, because we really should > look into moving hte ask-password onto kdbus and the kernel keyring, > and we hence shouldn't add cross-links to it now, where we already > know it should probably go away the way it currently is. > > The BSD lock scheme would be pretty much race-free afaics. The > controlling process stuff otoh would be race-ful, probably to the same > level as watching the ask-password stuff. > > Anyway, opinions on this? Like it. > I am slightly leaning towards the BSD lock solution I must say. In > particular as it is compatible with the story we kinda want to push > people using /dev/ttyS* towards, who really should use BSD locks too, > instead of the awful "LCK.." files... Zbyszek _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
