From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiri Pirko Subject: Re: [PATCH net] act_bpf: allow non-default TC_ACT opcodes as BPF exec outcome Date: Tue, 17 Mar 2015 23:27:53 +0100 Message-ID: <20150317222753.GA2169@nanopsycho.orion> References: <98364de656ad8034f008999121f57940af767b93.1426619298.git.daniel@iogearbox.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: davem@davemloft.net, netdev@vger.kernel.org, Alexei Starovoitov , Jamal Hadi Salim To: Daniel Borkmann Return-path: Received: from mail-wi0-f176.google.com ([209.85.212.176]:34107 "EHLO mail-wi0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932366AbbCQW15 (ORCPT ); Tue, 17 Mar 2015 18:27:57 -0400 Received: by wibg7 with SMTP id g7so54138931wib.1 for ; Tue, 17 Mar 2015 15:27:56 -0700 (PDT) Content-Disposition: inline In-Reply-To: <98364de656ad8034f008999121f57940af767b93.1426619298.git.daniel@iogearbox.net> Sender: netdev-owner@vger.kernel.org List-ID: Tue, Mar 17, 2015 at 08:25:57PM CET, daniel@iogearbox.net wrote: >Revisiting commit d23b8ad8ab23 ("tc: add BPF based action") with regards >to eBPF support, I was thinking that it might be better to improve >return semantics from a BPF program invoked through BPF_PROG_RUN(). > >Currently, in case filter_res is 0, we overwrite the default action >opcode with TC_ACT_SHOT. A default action opcode configured through tc's >m_bpf can be: TC_ACT_RECLASSIFY, TC_ACT_PIPE, TC_ACT_SHOT, TC_ACT_UNSPEC, >TC_ACT_OK. > >In cls_bpf, we have the possibility to overwrite the default class >associated with the classifier in case filter_res is _not_ 0xffffffff >(-1). > >That allows us to fold multiple [e]BPF programs into a single one, where >they would otherwise need to be defined as a separate classifier with >its own classid, needlessly redoing parsing work, etc. > >Similarly, we could do better in act_bpf: Since above TC_ACT* opcodes >are exported to UAPI anyway, we reuse them for return-code-to-tc-opcode >mapping, where we would allow above possibilities. Thus, like in cls_bpf, >a filter_res of 0xffffffff (-1) means that the configured _default_ action >is used. Any unkown return code from the BPF program would fail in >tcf_bpf() with TC_ACT_UNSPEC. > >Should we one day want to make use of TC_ACT_STOLEN or TC_ACT_QUEUED, >which both have the same semantics, we have the option to either use >that as a default action (filter_res of 0xffffffff) or non-default BPF >return code. > >All that will allow us to transparently use tcf_bpf() for both BPF >flavours. > >Signed-off-by: Daniel Borkmann >Cc: Jiri Pirko >Cc: Alexei Starovoitov >Cc: Jamal Hadi Salim >--- > Note, act_bpf has not been officially released with 4.0, so we can > still address it. Thanks for taking care of this Daniel Acked-by: Jiri Pirko