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[2a01:cb05:923c:9a00:2e69:150:7170:bd3]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43b919dfb54sm14881269f8f.31.2026.03.27.05.58.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 27 Mar 2026 05:58:45 -0700 (PDT) Date: Fri, 27 Mar 2026 13:58:42 +0100 From: Guillaume Nault To: Qingfang Deng Cc: Sebastian Andrzej Siewior , Shuah Khan , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Felix Maurer , Antonio Quartulli , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-ppp@vger.kernel.org, netdev@vger.kernel.org, Paul Mackerras Subject: Re: [PATCH net-next v4] selftests: net: add tests for PPP Message-ID: References: <20260326021642.29170-1-dqfext@gmail.com> <20260326081304.xKa7-s_1@linutronix.de> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Fri, Mar 27, 2026 at 08:39:11PM +0800, Qingfang Deng wrote: > On Fri, Mar 27, 2026 at 7:28 PM Guillaume Nault wrote: > > > > On Thu, Mar 26, 2026 at 04:26:23PM +0800, Qingfang Deng wrote: > > > Hi Sebastian, > > > > > > On Thu, Mar 26, 2026 at 4:13 PM Sebastian Andrzej Siewior > > > wrote: > > > > > > > > On 2026-03-26 10:16:24 [+0800], Qingfang Deng wrote: > > > > > Add ping and iperf3 tests for ppp_async.c and pppoe.c. > > > > > > > > Oh thank you for doing this. > > > > I haven't look in detail but this cover the "invalid loop" cases that > > > > ppp tries to catch? > > > > > > By "invalid loop", do you mean transmit recursion? > > > https://lore.kernel.org/all/20250715150806.700536-2-bigeasy@linutronix.de/ > > > > > > AFAIK, this can only happen with PPTP or L2TP, which were not included > > > in this patch. > > > > The problem was originally reproduced using L2TP, indeed. But I guess > > that it could also be reproduced with PPPoE by using a UDP tunnel > > device like VXLAN (like sending a packet through a PPP interface, > > handled by PPPoE, running on top of a VXLAN device, that routes the UDP > > encapsulated packet back to the original PPP interface). > > Yeah I've thought of that also. It can technically happen, though > there's no practical use. For self tests purpose, I may just add the > recursion test into PPTP or L2TP tests. Yes, no problem. > Regards, > Qingfang >