Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754713AbdGUShC (ORCPT ); Fri, 21 Jul 2017 14:37:02 -0400 Received: from mx2.suse.de ([195.135.220.15]:59517 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754596AbdGUSg6 (ORCPT ); Fri, 21 Jul 2017 14:36:58 -0400 From: Benjamin Poirier To: Jeff Kirsher Cc: Lennart Sorensen , intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 4/5] e1000e: Separate signaling for link check/link up Date: Fri, 21 Jul 2017 11:36:26 -0700 Message-Id: <20170721183627.13373-4-bpoirier@suse.com> X-Mailer: git-send-email 2.13.2 In-Reply-To: <20170721183627.13373-1-bpoirier@suse.com> References: <20170721160937.GA22632@csclub.uwaterloo.ca> <20170721183627.13373-1-bpoirier@suse.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2856 Lines: 82 Lennart reported the following race condition: \ e1000_watchdog_task \ e1000e_has_link \ hw->mac.ops.check_for_link() === e1000e_check_for_copper_link /* link is up */ mac->get_link_status = false; /* interrupt */ \ e1000_msix_other hw->mac.get_link_status = true; link_active = !hw->mac.get_link_status /* link_active is false, wrongly */ This problem arises because the single flag get_link_status is used to signal two different states: link status needs checking and link status is down. Avoid the problem by using the return value of .check_for_link to signal the link status to e1000e_has_link(). Reported-by: Lennart Sorensen Signed-off-by: Benjamin Poirier --- drivers/net/ethernet/intel/e1000e/mac.c | 11 ++++++++--- drivers/net/ethernet/intel/e1000e/netdev.c | 2 +- 2 files changed, 9 insertions(+), 4 deletions(-) diff --git a/drivers/net/ethernet/intel/e1000e/mac.c b/drivers/net/ethernet/intel/e1000e/mac.c index b322011ec282..f457c5703d0c 100644 --- a/drivers/net/ethernet/intel/e1000e/mac.c +++ b/drivers/net/ethernet/intel/e1000e/mac.c @@ -410,6 +410,9 @@ void e1000e_clear_hw_cntrs_base(struct e1000_hw *hw) * Checks to see of the link status of the hardware has changed. If a * change in link status has been detected, then we read the PHY registers * to get the current speed/duplex if link exists. + * + * Returns a negative error code (-E1000_ERR_*) or 0 (link down) or 1 (link + * up). **/ s32 e1000e_check_for_copper_link(struct e1000_hw *hw) { @@ -423,7 +426,7 @@ s32 e1000e_check_for_copper_link(struct e1000_hw *hw) * Change or Rx Sequence Error interrupt. */ if (!mac->get_link_status) - return 0; + return 1; /* First we want to see if the MII Status Register reports * link. If so, then we want to get the current speed/duplex @@ -461,10 +464,12 @@ s32 e1000e_check_for_copper_link(struct e1000_hw *hw) * different link partner. */ ret_val = e1000e_config_fc_after_link_up(hw); - if (ret_val) + if (ret_val) { e_dbg("Error configuring flow control\n"); + return ret_val; + } - return ret_val; + return 1; } /** diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c index fc6a1d9999b2..5a8ab1136566 100644 --- a/drivers/net/ethernet/intel/e1000e/netdev.c +++ b/drivers/net/ethernet/intel/e1000e/netdev.c @@ -5081,7 +5081,7 @@ static bool e1000e_has_link(struct e1000_adapter *adapter) case e1000_media_type_copper: if (hw->mac.get_link_status) { ret_val = hw->mac.ops.check_for_link(hw); - link_active = !hw->mac.get_link_status; + link_active = ret_val > 0; } else { link_active = true; } -- 2.13.2