From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Ahern Subject: Re: [PATCH v2 net-next 1/8] bpf: Add support for recursively running cgroup sock filters Date: Thu, 31 Aug 2017 14:53:31 -0600 Message-ID: <1db3d38a-dfb5-87de-4aa1-47ecd40f29a2@gmail.com> References: <1503687941-626-1-git-send-email-dsahern@gmail.com> <1503687941-626-2-git-send-email-dsahern@gmail.com> <20170826024957.m5ita6usxihywmdd@ast-mbp> <20170831142201.GB1599492@devbig577.frc2.facebook.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, daniel@iogearbox.net, ast@kernel.org, davem@davemloft.net To: Tejun Heo , Alexei Starovoitov Return-path: Received: from mail-pf0-f195.google.com ([209.85.192.195]:38104 "EHLO mail-pf0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750908AbdHaUxe (ORCPT ); Thu, 31 Aug 2017 16:53:34 -0400 Received: by mail-pf0-f195.google.com with SMTP id r187so426983pfr.5 for ; Thu, 31 Aug 2017 13:53:34 -0700 (PDT) In-Reply-To: <20170831142201.GB1599492@devbig577.frc2.facebook.com> Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: On 8/31/17 8:22 AM, Tejun Heo wrote: > On Sun, Aug 27, 2017 at 08:49:23AM -0600, David Ahern wrote: >> On 8/25/17 8:49 PM, Alexei Starovoitov wrote: >>> >>>> + if (prog && curr_recursive && !new_recursive) >>>> + /* if a parent has recursive prog attached, only >>>> + * allow recursive programs in descendent cgroup >>>> + */ >>>> + return -EINVAL; >>>> + >>>> old_prog = cgrp->bpf.prog[type]; >>> >>> ... I'm struggling to completely understand how it interacts >>> with BPF_F_ALLOW_OVERRIDE. >> >> The 2 flags are completely independent. The existing override logic is >> unchanged. If a program can not be overridden, then the new recursive >> flag is irrelevant. > > I'm not sure all four combo of the two flags makes sense. Can't we > have something simpler like the following? > > 1. None: No further bpf programs allowed in the subtree. > > 2. Overridable: If a sub-cgroup installs the same bpf program, this > one yields to that one. > > 3. Recursive: If a sub-cgroup installs the same bpf program, that > cgroup program gets run in addition to this one. > > Note that we can have combinations of overridables and recursives - > both allow further programs in the sub-hierarchy and the only > distinction is whether that specific program behaves when that > happens. > I am going to send v3 for patches 2-6 and 8 - the uncontested patches. Alexei and I will meet in L.A. the week of Sept 11-15 to discuss the recursive implementation (Patch 1 and its testing, patch 7).