From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH] net: fib: fix incorrect call_rcu_bh() Date: Tue, 07 Aug 2012 18:48:14 +0200 Message-ID: <1344358094.28967.116.camel@edumazet-glaptop> References: <1344336431.28967.14.camel@edumazet-glaptop> <20120807163454.GF2378@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: David Miller , netdev To: paulmck@linux.vnet.ibm.com Return-path: Received: from mail-bk0-f46.google.com ([209.85.214.46]:58711 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752946Ab2HGQsT (ORCPT ); Tue, 7 Aug 2012 12:48:19 -0400 Received: by bkwj10 with SMTP id j10so1522815bkw.19 for ; Tue, 07 Aug 2012 09:48:18 -0700 (PDT) In-Reply-To: <20120807163454.GF2378@linux.vnet.ibm.com> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, 2012-08-07 at 09:34 -0700, Paul E. McKenney wrote: > On Tue, Aug 07, 2012 at 12:47:11PM +0200, Eric Dumazet wrote: > > From: Eric Dumazet > > > > After IP route cache removal, I believe rcu_bh() has very little use and > > we should remove this RCU variant, since it adds some cycles in fast > > path. > > Do you mean remove all uses of RCU-bh globally and also removing the > implementation itself? That would actually be a good thing, from my > perspective. > Yes I meant that there are now too few rcu_bh users, and that they probably could switch to regular rcu. We could then remove the implementation. rcu_bh was needed because we could sit forever in softirq mode in one cpu, and we needed to allocate/free dsts with RCU protection.