From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [PATCH RESEND 0/4] device_cgroup: replace internally whitelist with exception list Date: Thu, 16 Aug 2012 13:08:44 -0700 Message-ID: <20120816130844.6f26530d.akpm@linux-foundation.org> References: <20120809190414.773462171@muttley.lan.cathedral> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20120809190414.773462171-+5JutNtNrJPwzbzh4h2Q61C45dnP8DBc@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" To: aris-moeOTchvdi7YtjvyW6yDsg@public.gmane.org Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Tejun Heo , Li Zefan On Thu, 09 Aug 2012 15:04:14 -0400 aris-moeOTchvdi7YtjvyW6yDsg@public.gmane.org wrote: > The original model of device_cgroup is having a whitelist where all the > allowed devices are listed. The problem with this approach is that is > impossible to have the case of allowing everything but few devices. > > The reason for that lies in the way the whitelist is handled internally: > since there's only a whitelist, the "all devices" entry would have to be > removed and replaced by the entire list of possible devices but the ones > that are being denied. Since dev_t is 32 bits long, representing the allowed > devices as a bitfield is not memory efficient. > > This patch replaces the "whitelist" by a "exceptions" list and the default > policy is kept as "deny_all" variable in dev_cgroup structure. The patches look reasonable to me. I suggest you resend them after kernel summit and cc a few additional people: Serge Hallyn, Pavel Emelyanov and James Morris.