Hi Mats, On 2016-05-17 12:03, Mats Karrman wrote: > Hi Felix, others, > > I have been experiencing problems with the init scripts dispatch > suddenly stopping (indefinitely). > This happens maybe once in 100 reboots. > After inserting a new start script that launches another daemon > (cgrulesengd) very early in the boot process, the failures started to > come a lot more frequently, maybe once in 10 reboots, making this a real > issue. > I'm normally using the versions of procd and libubox selected by OpenWRT > BB branch but I have tested the latest versions from the git repos with > the same result. > So far I have only got this to happen on a quite fast board (ARM dual > CorexA9 @ 1GHz). > Inserting trace prints in libubox changes behavior, also suggesting the > problem is timing dependent. > > When init hangs: > - it is still possible to log in on console > - there is always a zombie start script, e.g. S11sysctl. > - by killing a process (e.g. ubusd or cgrulesengd) the init process > continues. > - otherwise generating an event, e.g inserting something into a USB port > also makes the init continue. > > I have traced the problem down to the "epoll_wait" call in > libubox::uloop.c::uloop_fetch_events(). > The following patch makes sure epoll_wait is never called without a timeout. > My tests show that this solves the problem. > I have been able to observe the case when the boot gets stuck and then > continues after the 8s timeout. > However I'm not sure that this is the correct fix for the problem as > there may be other reasons that there is no event in the first place. > Your feedback would be welcome! I just took a look at the code and uloop's processing of signals looked a bit racy to me. I've pushed a commit that makes it use signalfd if available. I also found that waitpid wasn't being retried on signal interrupt, so I added an extra check there. The changes are in libubox git, but not in OpenWrt/LEDE yet. Please test if this fixes your issue.
Thanks, - Felix _______________________________________________ Lede-dev mailing list Lede-dev@lists.infradead.org http://lists.infradead.org/mailman/listinfo/lede-dev
