From mboxrd@z Thu Jan 1 00:00:00 1970 From: Francois Romieu Subject: Re: Realtek 8139 driver (8139too.c) TX Timeout doesn't allow interrupt handler to disable receive interrupts at high bi-directional traffic Date: Thu, 30 Nov 2006 00:32:19 +0100 Message-ID: <20061129233219.GD18057@electric-eye.fr.zoreil.com> References: <010C7BAE6783F34D9AC336EE5A01A08802D2D762@dbde01.ent.ti.com> <20061129122444.0614cf56@freekitty> <20061129224400.GC18057@electric-eye.fr.zoreil.com> <20061129145054.741ad7c5@freekitty> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "Basheer, Mansoor Ahamed" , netdev@vger.kernel.org Return-path: Received: from electric-eye.fr.zoreil.com ([213.41.134.224]:3534 "EHLO fr.zoreil.com") by vger.kernel.org with ESMTP id S967401AbWK2Xeg (ORCPT ); Wed, 29 Nov 2006 18:34:36 -0500 To: Stephen Hemminger Content-Disposition: inline In-Reply-To: <20061129145054.741ad7c5@freekitty> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Stephen Hemminger : > Francois Romieu wrote: > > Stephen Hemminger : > > [...] > > > @@ -1682,12 +1685,11 @@ static void rtl8139_tx_timeout_task (voi > > > rtl8139_tx_clear (tp); > > > spin_unlock_irq(&tp->lock); > > > > > > + netif_poll_enable(); > > ^ -> dev > > > + > > > /* ...and finally, reset everything */ > > > - if (netif_running(dev)) { > > > - rtl8139_hw_start (dev); > > > - netif_wake_queue (dev); > > > - } > > > - spin_unlock_bh(&tp->rx_lock); > > > + rtl8139_hw_start (dev); > > > + netif_wake_queue (dev); > > > } > > > > rtl8139_hw_start() may mess with cur_rx, whence a race with rtl8139_rx() > > if an in-flight interruption enables it a bit too fast. I'd rather go > > with: > > but rt8139_rx is not possible here because we have blocked the poll > routine from starting. Basically it uses the NAPI rx scheduler bit > to replace the rx_lock. 1 - the irq handler is waiting for tp->lock 2 - rtl8139_tx_timeout_task releases the lock 3 - rtl8139_tx_timeout_task issues netif_poll_enable 4 - the irq handler schedules ->poll(), returns 5 - rtl8139_hw_start() races with ->poll(), aka rtl8139_rx(), for cur_rx -- Ueimor