From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael Chan" Subject: Re: Regression in net-2.6.24? Date: Thu, 11 Oct 2007 20:17:16 -0700 Message-ID: <1192159036.6889.6.camel@dell> References: <20071011.164827.64988925.davem@davemloft.net> <20071011165548.6545b207@freepuppy.rosehill> <20071011.171743.118962219.davem@davemloft.net> <20071011.181449.130846976.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: shemminger@linux-foundation.org, takano@axe-inc.co.jp, "netdev" , ilpo.jarvinen@helsinki.fi To: "David Miller" Return-path: Received: from mms3.broadcom.com ([216.31.210.19]:1620 "EHLO MMS3.broadcom.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755151AbXJLCVY (ORCPT ); Thu, 11 Oct 2007 22:21:24 -0400 In-Reply-To: <20071011.181449.130846976.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Thu, 2007-10-11 at 18:14 -0700, David Miller wrote: > + while (1) { > + work_done = tg3_poll_work(tp, work_done, budget); > + > + if (unlikely(tp->tg3_flags & TG3_FLAG_TX_RECOVERY_PENDING)) > + goto tx_recovery; > + > + if (unlikely(work_done >= budget)) > + break; > + > + if (likely(!tg3_has_work(tp))) { > + struct tg3_hw_status *sblk = tp->hw_status; > + --> new status block DMA > + if (tp->tg3_flags & TG3_FLAG_TAGGED_STATUS) { > + tp->last_tag = sblk->status_tag; > + rmb(); > + } else > + sblk->status &= ~SD_STATUS_UPDATED; We need to read the sblk->status_tag before calling tg3_has_work(). If a new status block DMA happens in between (shown above), tp->last_tag will get the new tag and we will end up acknowledging work that we haven't processed. I'll go over this some more tonight and will send a patch to refine it. Thanks. > + > + netif_rx_complete(tp->dev, napi); > + tg3_restart_ints(tp); > + break; > + }