From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net 1/1] tipc: fix problem with parallel link synchronization mechanism Date: Wed, 29 Apr 2015 15:09:23 -0400 (EDT) Message-ID: <20150429.150923.1291697432920867232.davem@davemloft.net> References: <1430254744-10081-1-git-send-email-jon.maloy@ericsson.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, paul.gortmaker@windriver.com, erik.hugne@ericsson.com, ying.xue@windriver.com, maloy@donjonn.com, tipc-discussion@lists.sourceforge.net To: jon.maloy@ericsson.com Return-path: Received: from shards.monkeyblade.net ([149.20.54.216]:50234 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751006AbbD2TJ0 (ORCPT ); Wed, 29 Apr 2015 15:09:26 -0400 In-Reply-To: <1430254744-10081-1-git-send-email-jon.maloy@ericsson.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Jon Maloy Date: Tue, 28 Apr 2015 16:59:04 -0400 > Currently, we try to accumulate arrived packets in the links's > 'deferred' queue during the parallel link syncronization phase. > > This entails two problems: > > - With an unlucky combination of arriving packets the algorithm > may go into a lockstep with the out-of-sequence handling function, > where the synch mechanism is adding a packet to the deferred queue, > while the out-of-sequence handling is retrieving it again, thus > ending up in a loop inside the node_lock scope. > > - Even if this is avoided, the link will very often send out > unnecessary protocol messages, in the worst case leading to > redundant retransmissions. > > We fix this by just dropping arriving packets on the upcoming link > during the synchronization phase, thus relying on the retransmission > protocol to resolve the situation once the two links have arrived to > a synchronized state. > > Reviewed-by: Erik Hugne > Reviewed-by: Ying Xue > Signed-off-by: Jon Maloy Applied, thanks Jon.