From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: [PATCH/RFA] sch_generic: fix carrier-on bug? Date: Tue, 16 Oct 2007 17:55:55 -0400 Message-ID: <20071016215555.GA4732@havoc.gtf.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org, LKML To: David Miller Return-path: Received: from havoc.gtf.org ([69.61.125.42]:51481 "EHLO havoc.gtf.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761718AbXJPVz4 (ORCPT ); Tue, 16 Oct 2007 17:55:56 -0400 Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org While looking at a net driver with the following construct, if (!netif_carrier_ok(dev)) netif_carrier_on(dev); it stuck me that the netif_carrier_ok() check was redundant, since netif_carrier_on() checks bit __LINK_STATE_NOCARRIER anyway. This is the same reason why netif_queue_stopped() need not be called prior to netif_wake_queue(). This is true, but there is however an unwanted side effect from assuming that netif_carrier_on() can be called multiple times: it touches the watchdog, regardless of pre-existing carrier state. The fix: move watchdog-up inside the bit-cleared code path. Signed-off-by: Jeff Garzik --- This looks like an obvious bug fix to me, but I found it by reading code rather than hitting it in the field. Review appreciated. net/sched/sch_generic.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c index 95ae119..e01d576 100644 --- a/net/sched/sch_generic.c +++ b/net/sched/sch_generic.c @@ -249,10 +249,11 @@ static void dev_watchdog_down(struct net_device *dev) */ void netif_carrier_on(struct net_device *dev) { - if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) + if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) { linkwatch_fire_event(dev); - if (netif_running(dev)) - __netdev_watchdog_up(dev); + if (netif_running(dev)) + __netdev_watchdog_up(dev); + } } /**