From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Subject: Re: [PATCH] net: fib: fix incorrect call_rcu_bh() Date: Tue, 7 Aug 2012 10:07:02 -0700 Message-ID: <20120807170702.GH2378@linux.vnet.ibm.com> References: <1344336431.28967.14.camel@edumazet-glaptop> <20120807163454.GF2378@linux.vnet.ibm.com> <1344358094.28967.116.camel@edumazet-glaptop> Reply-To: paulmck@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: David Miller , netdev To: Eric Dumazet Return-path: Received: from e9.ny.us.ibm.com ([32.97.182.139]:40894 "EHLO e9.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752081Ab2HGR2e (ORCPT ); Tue, 7 Aug 2012 13:28:34 -0400 Received: from /spool/local by e9.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 7 Aug 2012 13:28:33 -0400 Received: from d01relay06.pok.ibm.com (d01relay06.pok.ibm.com [9.56.227.116]) by d01dlp03.pok.ibm.com (Postfix) with ESMTP id 942B23C60A41 for ; Tue, 7 Aug 2012 13:07:14 -0400 (EDT) Received: from d03av01.boulder.ibm.com (d03av01.boulder.ibm.com [9.17.195.167]) by d01relay06.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q77H77HN9044030 for ; Tue, 7 Aug 2012 13:07:07 -0400 Received: from d03av01.boulder.ibm.com (loopback [127.0.0.1]) by d03av01.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q77H72ZY005231 for ; Tue, 7 Aug 2012 11:07:03 -0600 Content-Disposition: inline In-Reply-To: <1344358094.28967.116.camel@edumazet-glaptop> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, Aug 07, 2012 at 06:48:14PM +0200, Eric Dumazet wrote: > 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. Very cool!!! Anything I can do to help, aside of course from the final removal of RCU-bh support? Thanx, Paul