From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Ostrowski Subject: Re: [PATCH, untested] Support for PPPOE on SMP Date: 25 Jun 2003 14:00:55 -0400 Sender: netdev-bounce@oss.sgi.com Message-ID: <1056564055.1944.2041.camel@brick.watson.ibm.com> References: <20030625072602.529AF2C0B9@lists.samba.org> <1056547262.1945.1436.camel@brick.watson.ibm.com> <20030625091531.5ebed618.shemminger@osdl.org> <20030625122128.V84526@shell.cyberus.ca> <20030625093902.7431efc3.shemminger@osdl.org> <20030625125518.N84526@shell.cyberus.ca> <20030625104001.476ee314.shemminger@osdl.org> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Jamal Hadi , rusty@rustcorp.com.au, "David S. Miller" , Paul MacKerras , netdev@oss.sgi.com, fcusack@samba.org, carlson@workingcode.com Return-path: To: Stephen Hemminger In-Reply-To: <20030625104001.476ee314.shemminger@osdl.org> Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org On Wed, 2003-06-25 at 13:40, Stephen Hemminger wrote: > For PPPoE, the session management needs to be in kernel space, with the policy > in user space. What if the kernel, initialized the session when it saw > the discovery and notified the pppd, session would not be established > until ppd accepted the connection. This would be more like a socket > protocol without auto-accept like TCP. Any data for the session would > then stay queued until it was accepted or rejected. > Regardless of the solution take for the session-initiation race, any solution would fall apart if SMP softIRQ's can reorder packets (that is it would result in dropped packets). Only once there is a solution for this reordering problem does it make sense to consider the options for handling this race. PPPoE also doesn't exactly cleanly fit nicely into the standard bind()/listen()/accept()/connect() mould. I've been convinced that negotiation/discovery belongs in pppd and so would like to avoid adding connection detection logic into the kernel. Finally, please keep in mind that with PPPoE when we do hit this problem the effect is that PPP session establishment takes a bit longer since we have to wait for an LCP timeout and retransmit. I am much more curious about how other protocols may be affected by packet reordering. -- Michal Ostrowski