Tvheadend

Copying from https://github.com/tvheadend/tvheadend/pull/1090#issuecomment-378722161

With Tvheadend as of April 4 (d941885), Tvheadend deadlocks during shutdown (ie. systemctl stop tvheadend) if at least one channel has been descrambled through a CAM via the DDCI implementation. It doesn't if the CAM wasn't used at all during the process' lifetime. From the gdb backtrace (attached) it looks like it's waiting in linuxdvb_ddci_rd_thread_stop, but this guess could aswell be just wrong.

I can't reproduce this right now with current GIT HEAD (595fd17) as I'm getting crashes and deadlocks all over the place (last one was in tvhlog.c) when trying to do so. Copying the reported problem to redmine anyway so it won't get lost in the GitHub PR comment.