From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jacob Keller Subject: [RFC PATCH] net: don't set __LINK_STATE_START until after dev->open() call Date: Mon, 7 Aug 2017 15:24:21 -0700 Message-ID: <20170807222421.11897-1-jacob.e.keller@intel.com> Cc: Jacob Keller To: netdev@vger.kernel.org Return-path: Received: from mga02.intel.com ([134.134.136.20]:5229 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751743AbdHGWY2 (ORCPT ); Mon, 7 Aug 2017 18:24:28 -0400 Sender: netdev-owner@vger.kernel.org List-ID: Fix an issue with relying on netif_running() which could be true during when dev->open() handler is being called, even if it would exit with a failure. This ensures the state does not get set and removed with a narrow race for other callers to read it as open when infact it never finished opening. Signed-off-by: Jacob Keller --- I found this as a result of debugging a race condition in the i40evf driver, in which we assumed that netif_running() would not be true until after dev->open() had been called and succeeded. Unfortunately we can't hold the rtnl_lock() while checking netif_running() because it would cause a deadlock between our reset task and our ndo_open handler. I am wondering whether the proposed change is acceptable here, or whether some ndo_open handlers rely on __LINK_STATE_START being true prior to their being called? net/core/dev.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index 1d75499add72..11953af90427 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -1362,8 +1362,6 @@ static int __dev_open(struct net_device *dev) if (ret) return ret; - set_bit(__LINK_STATE_START, &dev->state); - if (ops->ndo_validate_addr) ret = ops->ndo_validate_addr(dev); @@ -1372,9 +1370,8 @@ static int __dev_open(struct net_device *dev) netpoll_poll_enable(dev); - if (ret) - clear_bit(__LINK_STATE_START, &dev->state); - else { + if (!ret) + set_bit(__LINK_STATE_START, &dev->state); dev->flags |= IFF_UP; dev_set_rx_mode(dev); dev_activate(dev); -- 2.14.0.rc1.251.g593d8d6362ce