Date: Fri, 22 Jun 2012 19:50:01 +0300 From: Alexander Motin <mav@FreeBSD.org> To: "Kenneth D. Merry" <ken@FreeBSD.org> Cc: FreeBSD current <freebsd-current@freebsd.org> Subject: Re: minor GEOM disk API change coming Message-ID: <4FE4A239.5030000@FreeBSD.org>
next in thread | raw e-mail | index | archive | help
Hi. I understand problem you are going to fix and I think your patch should do it. What I don't very like is addition of new GEOM method. Now GEOM doesn't need it because all internal open/close operations and provider destructions there protected by the topology SX lock. Unluckily that lock doesn't cover g_wither_provider(), called by disk_gone() while holding CAM SIM lock. If not that SIM lock, it would be enough to just grab and drop GEOM topology lock to ensure that no new open() calls will follow. Indirect way to do it could be to post GEOM event that would drop the reference as soon as it will be handled and can obtain the topology lock. Unluckily it uses malloc() for event storage and also can be unreliable if called from under the SIM mutex lock. So it seems many things would be much easier if it was possible to drop SIM lock inside periph invalidate method, but now it is unsafe That is not an objection, just some thoughts about. -- Alexander Motin
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?4FE4A239.5030000>