From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S269940AbUJTK0v (ORCPT ); Wed, 20 Oct 2004 06:26:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S269941AbUJSWTh (ORCPT ); Tue, 19 Oct 2004 18:19:37 -0400 Received: from mustang.oldcity.dca.net ([216.158.38.3]:51685 "HELO mustang.oldcity.dca.net") by vger.kernel.org with SMTP id S269946AbUJSWK6 (ORCPT ); Tue, 19 Oct 2004 18:10:58 -0400 Subject: Re: tun.c patch to fix "smp_processor_id() in preemptible code" From: Lee Revell To: Herbert Xu Cc: vda@port.imtp.ilyichevsk.odessa.ua, Linux Network Development , linux-kernel , maxk@qualcomm.com, irda-users@lists.sourceforge.net In-Reply-To: <20041019215401.GA16427@gondor.apana.org.au> References: <1098222676.23367.18.camel@krustophenia.net> <20041019215401.GA16427@gondor.apana.org.au> Content-Type: text/plain Message-Id: <1098223857.23367.35.camel@krustophenia.net> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.6 Date: Tue, 19 Oct 2004 18:10:58 -0400 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2004-10-19 at 17:54, Herbert Xu wrote: > On Tue, Oct 19, 2004 at 05:51:17PM -0400, Lee Revell wrote: > > > > Ok, here is the correct patch. If this is really just a matter of > > performance, and not required for correctness, disabling preemption is > > broken, right? > > No if you're doing this then you should get rid of netif_rx_ni() > altogether. But before you do that please ask all the people who > call it. There are not a lot of them: drivers/s390/net/ctcmain.c drivers/s390/net/netiucv.c drivers/net/irda/vlsi_ir.c drivers/net/tun.c >>From netiuvc.c: /* * Since receiving is always initiated from a tasklet (in iucv.c), * we must use netif_rx_ni() instead of netif_rx() */ This implies that the author thought it was a matter of correctness to use netif_rx_ni vs. netif_rx. But it looks like the only difference is that the former sacrifices preempt-safety for performance. I could not find maintainers for the two s390 drivers, or a specific maintainer for vlsi_ir. Lee