From mboxrd@z Thu Jan 1 00:00:00 1970 From: Subject: [PATCH net] net: ena: fix race condition between device reset and link up setup Date: Sat, 18 Nov 2017 03:05:36 +0000 Message-ID: <1510974336-105124-1-git-send-email-netanel@amazon.com> Mime-Version: 1.0 Content-Type: text/plain Cc: Netanel Belgazal , , , , , , , , To: , Return-path: Received: from smtp-fw-6001.amazon.com ([52.95.48.154]:44087 "EHLO smtp-fw-6001.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755437AbdKRDF5 (ORCPT ); Fri, 17 Nov 2017 22:05:57 -0500 Sender: netdev-owner@vger.kernel.org List-ID: From: Netanel Belgazal In rare cases, ena driver would reset and re-start the device, for example, in case of misbehaving application that causes transmit timeout The first step in the reset procedure is to stop the Tx traffic by calling ena_carrier_off(). After the driver have just started the device reset procedure, device happens to send an asynchronous notification (via AENQ) to the driver than there was a link change (to link-up state). This link change is mapped to a call to netif_carrier_on() which re-activates the Tx queues, violating the assumption of no tx traffic until device reset is completed, as the reset task might still be in the process of queues initialization, leading to an access to uninitialized memory. --- drivers/net/ethernet/amazon/ena/ena_netdev.c | 11 +++++++++-- drivers/net/ethernet/amazon/ena/ena_netdev.h | 3 ++- 2 files changed, 11 insertions(+), 3 deletions(-) diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.c b/drivers/net/ethernet/amazon/ena/ena_netdev.c index 5417e4da64ca..988d0383b4e7 100644 --- a/drivers/net/ethernet/amazon/ena/ena_netdev.c +++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c @@ -2579,6 +2579,7 @@ static int ena_restore_device(struct ena_adapter *adapter) bool wd_state; int rc; + set_bit(ENA_FLAG_ONGOING_RESET, &adapter->flags); rc = ena_device_init(ena_dev, adapter->pdev, &get_feat_ctx, &wd_state); if (rc) { dev_err(&pdev->dev, "Can not initialize device\n"); @@ -2592,6 +2593,11 @@ static int ena_restore_device(struct ena_adapter *adapter) goto err_device_destroy; } + clear_bit(ENA_FLAG_ONGOING_RESET, &adapter->flags); + /* Make sure we don't have a race with AENQ Links state handler */ + if (test_bit(ENA_FLAG_LINK_UP, &adapter->flags)) + netif_carrier_on(adapter->netdev); + rc = ena_enable_msix_and_set_admin_interrupts(adapter, adapter->num_queues); if (rc) { @@ -2618,7 +2624,7 @@ static int ena_restore_device(struct ena_adapter *adapter) ena_com_admin_destroy(ena_dev); err: clear_bit(ENA_FLAG_DEVICE_RUNNING, &adapter->flags); - + clear_bit(ENA_FLAG_ONGOING_RESET, &adapter->flags); dev_err(&pdev->dev, "Reset attempt failed. Can not reset the device\n"); @@ -3495,7 +3501,8 @@ static void ena_update_on_link_change(void *adapter_data, if (status) { netdev_dbg(adapter->netdev, "%s\n", __func__); set_bit(ENA_FLAG_LINK_UP, &adapter->flags); - netif_carrier_on(adapter->netdev); + if (!test_bit(ENA_FLAG_ONGOING_RESET, &adapter->flags)) + netif_carrier_on(adapter->netdev); } else { clear_bit(ENA_FLAG_LINK_UP, &adapter->flags); netif_carrier_off(adapter->netdev); diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.h b/drivers/net/ethernet/amazon/ena/ena_netdev.h index ed8bd0a579c4..3bbc003871de 100644 --- a/drivers/net/ethernet/amazon/ena/ena_netdev.h +++ b/drivers/net/ethernet/amazon/ena/ena_netdev.h @@ -272,7 +272,8 @@ enum ena_flags_t { ENA_FLAG_DEV_UP, ENA_FLAG_LINK_UP, ENA_FLAG_MSIX_ENABLED, - ENA_FLAG_TRIGGER_RESET + ENA_FLAG_TRIGGER_RESET, + ENA_FLAG_ONGOING_RESET }; /* adapter specific private data structure */ -- 2.7.3.AMZN