On Thu, Nov 1, 2018 at 2:15 PM Stephen Smalley <sds@xxxxxxxxxxxxx> wrote: > On 10/31/2018 04:31 PM, Stephen Smalley wrote: > > We'd like to > > replace the policy rwlock with RCU at some point; there is a very old > > patch that tried to do that once before, which eliminated the policy > > write lock altogether (policy switch became a single pointer update), > > but no one has yet taken that back up. > > For reference, here is that old patch that tried converting the policy > rwlock to RCU. It applies on Linux v2.6.9 (yes, it is that old). There > was a more recent effort by Peter Enderborg to convert to RCU to deal > with preempt disable holding, but I had some concerns with the approach > to booleans, see [1] > > Aside from the locking aspects, the other reason I mention it is that I > am unsure of the implications of your model of converting within the > sidtab for a future migration to RCU, since that doesn't seem amenable > to a read-copy-update sequence. I would definitely like to experiment with the RCU conversion at some point. I agree that the new model will probably need to be re-thought again for that, but I don't think it would make it more difficult to do everything right than it would be now. I have another idea how to rewrite the sidtab that should be more RCU-conversion-ready, so maybe I'll even drop this model after all... > > [1] > https://lore.kernel.org/selinux/20180530141104.28569-1-peter.enderborg@xxxxxxxx/ -- Ondrej Mosnacek <omosnace at redhat dot com> Associate Software Engineer, Security Technologies Red Hat, Inc. _______________________________________________ Selinux mailing list Selinux@xxxxxxxxxxxxx To unsubscribe, send email to Selinux-leave@xxxxxxxxxxxxx. To get help, send an email containing "help" to Selinux-request@xxxxxxxxxxxxx.
