[LAU] JACK hangs on openSUSE Tumbleweed

Hi *!

I've come across a mysterious problem - since a few days ago (openSUSE
Tumbleweed is a rolling release), JACK hangs during startup. If you
start it with QJackCtl, it will kill it after a while, but if you start
it from the console and strace it, you can see it hangs waiting for a futex:
[...]
sched_get_priority_min(SCHED_FIFO) = 1
sched_get_priority_max(SCHED_FIFO) = 99
mmap(NULL, 8392704, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANONYMOUS|MAP_STACK, -1, 0) = 0x7f9e76cfe000
mprotect(0x7f9e76cfe000, 4096, PROT_NONE) = 0
clone(child_stack=0x7f9e774fdfb0,
flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID,
parent_tidptr=0x7f9e774fe9d0, tls=0x7f9e774fe700,
child_tidptr=0x7f9e774fe9d0) = 4627
sched_setscheduler(4627, SCHED_FIFO, { 1 }) = 0
futex(0x7f9e774fed18, FUTEX_WAKE_PRIVATE, 1) = 1
munmap(0x7f9e7ba87000, 227354) = 0
futex(0x7f9e776ff078, FUTEX_WAKE_PRIVATE, 1) = 1
futex(0x7f9e774fe9d0, FUTEX_WAIT, 4627, NULL) = ? ERESTARTSYS (To be
restarted if SA_RESTART is set)
--- SIGWINCH {si_signo=SIGWINCH, si_code=SI_KERNEL} ---
futex(0x7f9e774fe9d0, FUTEX_WAIT, 4627, NULL

and hangs forever after.
It seems to be after acquiring SCHED_FIFO, but just to be sure I
verified that I'm still in group audio, and we still have
@audio - rtprio 95
@audio - memlock 3000000
in /etc/security/limits.conf.

The problem started at the same time kernel 3.19.3 came out for
Tumbleweed, but downgrading to older kernels in the 3.19 series or as
far back as 3.17 doesn't restore jack functionality. So it must be
something in userspace.

Other people have seen this [1] and solved it with the nuclear option,
i.e. downgrading to 13.2, which means a massive userspace rollback.

I wonder if someone could offer some advice as to where else to look...

I did the usual checkup regarding double installs, and I'm positive my
jackd installation is clean. The guys in [1] have used the package, and
I've tried both the package and a clean jack1 and jack2 build from
scratch, with all other libs cleared by hand and ldd relations checked.

Any inspiration welcome,

Jörn

[1]
https://forums.opensuse.org/showthread.php/506613-after-update-Tumbleweed-I-can-t-start-Jackd-Jack-Connection-Kit
(not a very insightful discussion)

-- 
Jörn Nettingsmeier
Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487
Meister für Veranstaltungstechnik (Bühne/Studio)
Tonmeister VDT
http://stackingdwarves.net
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