Re: [PATCH] fix race in AF_UNIX

Miklos Szeredi [off-list ref] writes:

And I think incremental GC algorithms are much too complex for this
task.  What I've realized, is that in fact we don't require a generic
garbage collection algorithm, just a much more specialized cycle
collection algorithm, since refcounting in struct file takes care of
the rest.

This would help with localizing the problem to the problematic sockets
(which have an in-flight unix socket), instead of having to blindly
traverse _all_ unix sockets in the system.

I'll look at reimplementing the GC with such an algorithm.

Ok.  If you can do it more simply have at it.

There are incremental garbage collectors that are essentially just the
current algorithm with fine-grained locking.  So we don't have to live
in a spin-lock the whole time.

If your approach fails we can look at something more fine-grained.

quoted

It appears clear that since we can't stop the world and garbage
collect we need an incremental collector.

Constraining ourselves to stopping unix sockets from going in flight
or coming out of flight during garbage collection should be OK I
think.  There's still a possibility of a DoS there, but it would only
be able to affect _very_ few applications.

Yes.

Eric