On Sun, 18 Apr 2021 at 20:58, Александр Недоцуков <bl...@bbnest.net> wrote: > > Hi All, > > After supposed locking fixes done in this commit: > 5245bf7b92b74e556527b4916a8deba386fe5772 > we have a broken nsdispatch(3) when system has a threaded nss module plugged > in. > > To illustrate the problem: > > $id bland > id: bland: no such user > t$LD_PRELOAD=/usr/lib/libthr.so id bland > uid=1001(bland) gid=500(domainusers) groups=500(domainusers),... > > $cat /etc/nsswitch.conf > group: files ldap > hosts: files mdns dns > netgroup: comapt > networks: files > passwd: files ldap > shells: files > services: files > protocols: files > rpc: files > > It seems that the commit in question was done under asumption that threading > model can never be changed during run-time, while previous code was taking > care of it by taking a copy of __isthreaded. > > I can not reach out Alex Rechardson who authored this change. Perhaps someone > else can step in and take care of it? > > Thanks, > Alexander.
Hi Alexander, I was away over the weekend so I wasn't able to revert it then. I've committed the revert as https://cgit.freebsd.org/src/commit/?id=738314e445ceac4d3dd6c77c636044141623b8dc and I am not convinced that __isthreaded changing is the real problem. This can only happen with fork() (which calls _thr_setthreaded(0)) since if it's currently false, the main thread is executing and we can't be spawning a new thread. I think the problem could be that fork() is called while the lock is held in one thread and therefore the new process ends up with a locked rwlock. I think the solution could be to add a pthread_atfork() callback that unlocks the rwlock. Sorry for the breakage! Alex _______________________________________________ freebsd-current@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
