From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oleg Nesterov Subject: Re: [NETPOLL] netconsole: fix soft lockup when removing module Date: Mon, 2 Jul 2007 13:24:08 +0400 Message-ID: <20070702092408.GA137@tv-sign.ru> References: <20070701173558.GA207@tv-sign.ru> <20070702063424.GA1639@ff.dom.local> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Linus Torvalds , Andrew Morton , "David S. Miller" , linux-kernel@vger.kernel.org, netdev@vger.kernel.org To: Jarek Poplawski Return-path: Received: from mail.screens.ru ([213.234.233.54]:36893 "EHLO mail.screens.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751333AbXGBJXt (ORCPT ); Mon, 2 Jul 2007 05:23:49 -0400 Content-Disposition: inline In-Reply-To: <20070702063424.GA1639@ff.dom.local> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 07/02, Jarek Poplawski wrote: > > > > --- a/net/core/netpoll.c > > > +++ b/net/core/netpoll.c > > > @@ -72,7 +72,8 @@ static void queue_process(struct work_struct *work) > > > netif_tx_unlock(dev); > > > local_irq_restore(flags); > > > > > > - schedule_delayed_work(&npinfo->tx_work, HZ/10); > > > + if (atomic_read(&npinfo->refcnt)) > > > + schedule_delayed_work(&npinfo->tx_work, HZ/10); > > > return; > > > } > > [...snip...] > > So, 2.6.21 needs something better (maybe you've found it btw.?), > but they weren't too interested, anyway. We can do a double flush trick. If queue_process() checks ->refcnt before schedule_delayed_work() like above, netpoll_cleanup() can do flush_scheduled_work(); // the next invocation of queue_process() // must see ->refcnt == 0 if (!cancel_delayed_work(&npinfo->tx_work)) { /* may be queued, wait for completion */ flush_scheduled_work(); } Jarek, I don't understand net/, a silly question. Why do we need the #2 chunk? Isn't it better to move skb_queue_purge(&npinfo->txq) after cancel_..._work() instead? Oleg.