From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Kirsher Subject: [net-next 2/6] e1000e: hitting BUG_ON() from napi_enable Date: Sat, 3 Dec 2011 03:44:27 -0800 Message-ID: <1322912671-6903-3-git-send-email-jeffrey.t.kirsher@intel.com> References: <1322912671-6903-1-git-send-email-jeffrey.t.kirsher@intel.com> Cc: Bruce Allan , netdev@vger.kernel.org, gospo@redhat.com, sassmann@redhat.com, Mike McElroy , Jeff Kirsher To: davem@davemloft.net Return-path: Received: from mga14.intel.com ([143.182.124.37]:23508 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754731Ab1LCLof (ORCPT ); Sat, 3 Dec 2011 06:44:35 -0500 In-Reply-To: <1322912671-6903-1-git-send-email-jeffrey.t.kirsher@intel.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Bruce Allan Based on a patch from Mike McElroy created against the out-of-tree e1000e driver: Hitting the BUG_ON in napi_enable(). Code inspection shows that this can only be triggered by calling napi_enable() twice without an intervening napi_disable(). I saw the following sequence of events in the stack trace: 1) We simulated a cable pull using an Extreme switch. 2) e1000_tx_timeout() was entered. 3) e1000_reset_task() was called. Saw the message from e_err() in the console log. 4) e1000_reinit_locked was called. This function calls e1000_down() and e1000_up(). These functions call napi_disable() and napi_enable() respectively. 5) Then on another thread, a monitor task saw carrier was down and executed 'ip set link down' and 'ip set link up' commands. 6) Saw the '_E1000_RESETTING'warning fron the e1000_close function. 7) Either the e1000_open() executed between the e1000_down() and e1000_up() calls in step 4 or the e1000_open() call executed after the e1000_up() call. In either case, napi_enable() is called twice which triggers the BUG_ON. Signed-off-by: Bruce Allan Cc: Mike McElroy Tested-by: Aaron Brown Signed-off-by: Jeff Kirsher --- drivers/net/ethernet/intel/e1000e/netdev.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c index 3c12e6a..ef6546f 100644 --- a/drivers/net/ethernet/intel/e1000e/netdev.c +++ b/drivers/net/ethernet/intel/e1000e/netdev.c @@ -3516,7 +3516,6 @@ int e1000e_up(struct e1000_adapter *adapter) clear_bit(__E1000_DOWN, &adapter->state); - napi_enable(&adapter->napi); if (adapter->msix_entries) e1000_configure_msix(adapter); e1000_irq_enable(adapter); @@ -3578,7 +3577,6 @@ void e1000e_down(struct e1000_adapter *adapter) e1e_flush(); usleep_range(10000, 20000); - napi_disable(&adapter->napi); e1000_irq_disable(adapter); del_timer_sync(&adapter->watchdog_timer); @@ -3901,6 +3899,8 @@ static int e1000_close(struct net_device *netdev) pm_runtime_get_sync(&pdev->dev); + napi_disable(&adapter->napi); + if (!test_bit(__E1000_DOWN, &adapter->state)) { e1000e_down(adapter); e1000_free_irq(adapter); -- 1.7.6.4