On Fri, 11 Dec 2020 17:45:45 +0100, Jaroslav Kysela wrote: > > Dne 11. 12. 20 v 9:38 Takashi Iwai napsal(a): > > Currently alsactl-restore tries to initialize the device when an error > > is found for restore action. But this isn't the right behavior in the > > case where the lock is held; it implies that another alsactl is > > running concurrently, hence you shouldn't initialize the card at the > > same time. The situation is found easily when two alsactls get > > started by both udev and systemd (note that those two invocations are > > the designed behavior, see /usr/lib/udev/rules.d/78-sound-cards.rules > > for details). > > > > This patch changes load_state() not to handle the initialization if > > the locking fails. > > The operation should serialize in this case (there's limit of 10 seconds which > should be enough to finish the initialization). The state_lock() function > should return -EBUSY when the file is locked (and I'm fine to change the > behaviour from 'init' to 'skip' for this lock state). > > It seems that -EEXIST is returned when the lock file exists, but the > open(file, O_CREAT|O_EXCL, 0644) caller has not enough priviledges to access > this file when another user owns the file. > > But alsactl from /lib/udev/rules.d/90-alsa-restore.rules and > /lib/systemd/system/alsa-restore.service should be run as root, right? Yes, it should be root. I also wondered how EEXIST comes, too. Maybe it's also the race between the first open(O_RDWR) and the second open(O_RDWR|O_CREAT|O_EXCL)? If so, it'd be better to go back again to the normal open(O_RDWR)? thanks, Takashi
