Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932905AbcDYPnn (ORCPT ); Mon, 25 Apr 2016 11:43:43 -0400 Received: from Chamillionaire.breakpoint.cc ([80.244.247.6]:60792 "EHLO Chamillionaire.breakpoint.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932705AbcDYPnm (ORCPT ); Mon, 25 Apr 2016 11:43:42 -0400 Date: Mon, 25 Apr 2016 17:43:39 +0200 From: Florian Westphal To: Francois Romieu Cc: Florian Westphal , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Jay Cliburn , Chris Snook Subject: Re: [PATCH net-next 2/6] atl1c: remove private tx lock Message-ID: <20160425154339.GA17538@breakpoint.cc> References: <1461526694-11367-1-git-send-email-fw@strlen.de> <1461526694-11367-3-git-send-email-fw@strlen.de> <20160424220529.GA29377@electric-eye.fr.zoreil.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160424220529.GA29377@electric-eye.fr.zoreil.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1563 Lines: 41 Francois Romieu wrote: > Florian Westphal : > [...] > > diff --git a/drivers/net/ethernet/atheros/atl1c/atl1c_main.c b/drivers/net/ethernet/atheros/atl1c/atl1c_main.c > > index d0084d4..a3200ea 100644 > > --- a/drivers/net/ethernet/atheros/atl1c/atl1c_main.c > > +++ b/drivers/net/ethernet/atheros/atl1c/atl1c_main.c > [...] > > @@ -2217,16 +2215,10 @@ static netdev_tx_t atl1c_xmit_frame(struct sk_buff *skb, > > } > > > > tpd_req = atl1c_cal_tpd_req(skb); > > - if (!spin_trylock_irqsave(&adapter->tx_lock, flags)) { > > - if (netif_msg_pktdata(adapter)) > > - dev_info(&adapter->pdev->dev, "tx locked\n"); > > - return NETDEV_TX_LOCKED; > > - } > > > > if (atl1c_tpd_avail(adapter, type) < tpd_req) { > > /* no enough descriptor, just stop queue */ > > netif_stop_queue(netdev); > > - spin_unlock_irqrestore(&adapter->tx_lock, flags); > > return NETDEV_TX_BUSY; > > } > > > > Play it safe and keep the implicit local_irq_{save / restore} call ? > > It may not be needed but it will help avoiding any unexpected regression > report pointing at the NETDEV_TX_LOCKED removal change. I thought about that but it doesn't prevent the irq handler from running on another CPU, so leaving it around seemed like cargo culting to me... I don't have an atl1c, but the atl1e in my laptop seems to work fine with the (similar) change. If you disagree I can respin with local_irq_save of course, but, if 'playing it safe' is main goal then its simpler to convert spin_trylock_irqsave to spin_lock_irqsave.