From mboxrd@z Thu Jan 1 00:00:00 1970 From: Enke Chen Subject: Re: [PATCH v5] kernel/signal: Signal-based pre-coredump notification Date: Wed, 21 Nov 2018 17:09:50 -0800 Message-ID: References: <458c04d8-d189-4a26-729a-bb1d1d751534@cisco.com> <7741efa7-a3f8-62a1-ba52-613883164643@cisco.com> <84460a77-a111-404e-4bad-88104a6e246e@cisco.com> <20181026082812.GA10581@redhat.com> <21f678a8-4001-df36-c26e-e96cf203b1b1@cisco.com> <20181029111804.GA24820@redhat.com> <0c197608-3b7e-ffd1-8943-801a60beb917@cisco.com> <20181030164628.GD7643@redhat.com> <20181121163711.2c00316784d221eb1750edb0@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20181121163711.2c00316784d221eb1750edb0@linux-foundation.org> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Andrew Morton Cc: Oleg Nesterov , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Peter Zijlstra , Arnd Bergmann , "Eric W. Biederman" , Khalid Aziz , Kate Stewart , Helge Deller , Greg Kroah-Hartman , Al Viro , Christian Brauner , Catalin Marinas , Will Deacon , Dave Martin , Mauro Carvalho Chehab , Michal Hocko , Rik van Riel List-Id: linux-arch.vger.kernel.org Hi, Andrew: On 11/21/18 4:37 PM, Andrew Morton wrote: > On Tue, 30 Oct 2018 17:46:29 +0100 Oleg Nesterov wrote: > >> On 10/29, Enke Chen wrote: >>> >>> Reviewed-by: Oleg Nesterov >> >> Hmm. I didn't say this ;) >> >> But OK, feel free to keep this tag. >> >> I do not like this feauture. > > Why is that? > >> But I see no technical problems in this version >> and I never pretented I understand the user-space needs, so I won't argue. > > The changelog appears to spell this all out quite well? Unusually > well, in my experience ;) I also followed up with a little more explanation in the email thread on 10/30/2018: --- As I explained earlier, the primary application is in the area of network high-availability / non-stop-forwarding where early fault notification and early action can help maintain BFD sessions and thus avoid unnecessary disruption to forwarding while the control-plane is recovering. --- BTW, I probably should have pointed out this earlier: BFD stands for "RFC 5880: Bi-directional forwarding detection". > > A couple of things... > > - We'll be looking for a manpage update please. (Search MAINTAINERS > for "manpage") Yes, I will submit a manpage update. Most of the text is already written in the patch description. > > - As it's a linux-specific feature, a test under > tools/testing/selftests would be appropriate. I don't know how much > that work will be. The selftest code was submitted on 10/25/2018: [PATCH] selftests/prctl: selftest for pre-coredump signal notification > Do we have other linux-specific signal extensions which could piggyback onto that? No. There are enough existing signals that an application can choose for this purpose, such as SIGUSR1, SIGUSR1, and any of the RT signals. Thanks. -- Enke From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from rcdn-iport-4.cisco.com ([173.37.86.75]:61286 "EHLO rcdn-iport-4.cisco.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732372AbeKVLqn (ORCPT ); Thu, 22 Nov 2018 06:46:43 -0500 Subject: Re: [PATCH v5] kernel/signal: Signal-based pre-coredump notification References: <458c04d8-d189-4a26-729a-bb1d1d751534@cisco.com> <7741efa7-a3f8-62a1-ba52-613883164643@cisco.com> <84460a77-a111-404e-4bad-88104a6e246e@cisco.com> <20181026082812.GA10581@redhat.com> <21f678a8-4001-df36-c26e-e96cf203b1b1@cisco.com> <20181029111804.GA24820@redhat.com> <0c197608-3b7e-ffd1-8943-801a60beb917@cisco.com> <20181030164628.GD7643@redhat.com> <20181121163711.2c00316784d221eb1750edb0@linux-foundation.org> From: Enke Chen Message-ID: Date: Wed, 21 Nov 2018 17:09:50 -0800 MIME-Version: 1.0 In-Reply-To: <20181121163711.2c00316784d221eb1750edb0@linux-foundation.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: Andrew Morton Cc: Oleg Nesterov , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Peter Zijlstra , Arnd Bergmann , "Eric W. Biederman" , Khalid Aziz , Kate Stewart , Helge Deller , Greg Kroah-Hartman , Al Viro , Christian Brauner , Catalin Marinas , Will Deacon , Dave Martin , Mauro Carvalho Chehab , Michal Hocko , Rik van Riel , "Kirill A. Shutemov" , Roman Gushchin , Marcos Paulo de Souza , Dominik Brodowski , Cyrill Gorcunov , Yang Shi , Jann Horn , Kees Cook , x86@kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, "Victor Kamensky (kamensky)" , xe-linux-external@cisco.com, Stefan Strogin , Enke Chen Message-ID: <20181122010950._00aO8i_dqt1bEDTANOqdAuyrW8iqQP61LeN8z-j2JI@z> Hi, Andrew: On 11/21/18 4:37 PM, Andrew Morton wrote: > On Tue, 30 Oct 2018 17:46:29 +0100 Oleg Nesterov wrote: > >> On 10/29, Enke Chen wrote: >>> >>> Reviewed-by: Oleg Nesterov >> >> Hmm. I didn't say this ;) >> >> But OK, feel free to keep this tag. >> >> I do not like this feauture. > > Why is that? > >> But I see no technical problems in this version >> and I never pretented I understand the user-space needs, so I won't argue. > > The changelog appears to spell this all out quite well? Unusually > well, in my experience ;) I also followed up with a little more explanation in the email thread on 10/30/2018: --- As I explained earlier, the primary application is in the area of network high-availability / non-stop-forwarding where early fault notification and early action can help maintain BFD sessions and thus avoid unnecessary disruption to forwarding while the control-plane is recovering. --- BTW, I probably should have pointed out this earlier: BFD stands for "RFC 5880: Bi-directional forwarding detection". > > A couple of things... > > - We'll be looking for a manpage update please. (Search MAINTAINERS > for "manpage") Yes, I will submit a manpage update. Most of the text is already written in the patch description. > > - As it's a linux-specific feature, a test under > tools/testing/selftests would be appropriate. I don't know how much > that work will be. The selftest code was submitted on 10/25/2018: [PATCH] selftests/prctl: selftest for pre-coredump signal notification > Do we have other linux-specific signal extensions which could piggyback onto that? No. There are enough existing signals that an application can choose for this purpose, such as SIGUSR1, SIGUSR1, and any of the RT signals. Thanks. -- Enke