From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net-next v5] net: x25: Queue received packets in the drivers instead of per-CPU queues Date: Tue, 06 Apr 2021 16:14:31 -0700 (PDT) Message-ID: <20210406.161431.1568805748449868568.davem@davemloft.net> References: <20210402093000.72965-1-xie.he.0141@gmail.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20210402093000.72965-1-xie.he.0141@gmail.com> List-ID: Content-Type: Text/Plain; charset="us-ascii" To: xie.he.0141@gmail.com Cc: ms@dev.tdt.de, kuba@kernel.org, corbet@lwn.net, khc@pm.waw.pl, linux-x25@vger.kernel.org, netdev@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org From: Xie He Date: Fri, 2 Apr 2021 02:30:00 -0700 > X.25 Layer 3 (the Packet Layer) expects layer 2 to provide a reliable > datalink service such that no packets are reordered or dropped. And > X.25 Layer 2 (the LAPB layer) is indeed designed to provide such service. > > However, this reliability is not preserved when a driver calls "netif_rx" > to deliver the received packets to layer 3, because "netif_rx" will put > the packets into per-CPU queues before they are delivered to layer 3. > If there are multiple CPUs, the order of the packets may not be preserved. > The per-CPU queues may also drop packets if there are too many. > > Therefore, we should not call "netif_rx" to let it queue the packets. > Instead, we should use our own queue that won't reorder or drop packets. > > This patch changes all X.25 drivers to use their own queues instead of > calling "netif_rx". The patch also documents this requirement in the > "x25-iface" documentation. > > Cc: Martin Schiller > Signed-off-by: Xie He This no longe applies to net-next, please respin. Thank you.