From: Elad Nachman <el...@gilat.com> Date: Tue, 17 Jan 2017 17:39:03 +0000
> What's more odd about this is that it's very unusual and strange for > a kernel function to invoke the restart mechanism because a lock is > being held - the point of the restart mechanism is to allow userspace > signal handlers to run, so it should only be used when there's a > signal pending. I think this is a hack in the IPv6 code to work > around some other issue. It's not unusal at all, if you actually grep for this under net/ you will see that it is in fact a common code pattern. It prevents deadlocks because the sysfs and other nodes that we are operating with can be unregistered by other threads of control holding the RTNL mutex. If we don't break out, we won't release our reference and therefore the RTNL mutex holding entity cannot make forward progress. This behavior is therefore very much intentional.
