From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [RFC] mlx5: fix error unwind in device start Date: Mon, 13 Aug 2018 08:20:49 -0700 Message-ID: <20180813082049.1758d647@xeon-e3> References: <20180801215952.25326-1-stephen@networkplumber.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Yongseok Koh , "dev@dpdk.org" , Stephen Hemminger To: Shahaf Shuler Return-path: Received: from mail-pg1-f194.google.com (mail-pg1-f194.google.com [209.85.215.194]) by dpdk.org (Postfix) with ESMTP id 012462661 for ; Mon, 13 Aug 2018 17:20:56 +0200 (CEST) Received: by mail-pg1-f194.google.com with SMTP id y4-v6so7648354pgp.9 for ; Mon, 13 Aug 2018 08:20:56 -0700 (PDT) In-Reply-To: List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On Mon, 13 Aug 2018 07:52:47 +0000 Shahaf Shuler wrote: > Hi Stephan, > > Thursday, August 2, 2018 1:00 AM, Stephen Hemminger: > > Subject: [RFC] mlx5: fix error unwind in device start > > > > The error handling in start of the mlx5 driver is buggy. > > For example, if setting up the flows fails the device driver will then get stuck > > in mlx5_flow_rxq_flags_clear waiting for something that will never happen. > > Looking at the code I cannot understand why the mlx5_flow_rxq_flags_clear get stuck nor to what it waits. > The function has few finite loops which are not depended in anything which happened before it at the device start. > > Moreover I tried to force either the mlx5_traffic_enable or the mlx5_flow_start to stop, however the results was the port failed to start but no stuck. > > Can you provide more details about the issue you saw there? > > > > > The problem is that the code jumps to a common error label and does > > unwind for portions of the driver which have not been setup. > > > > This suggested patch breaks it into different labels with each failure path only > > unwinding what was done. > > > > Also, the ethdev driver should not be manipulating the dev_started flag > > directly. That is handled by the common ethdev layer. > > > > I agree that maybe this code part can be better written, but my question before is whether we have an actual bug that we will solve w/ this change? > > > The patch works for the success case, but furthur testing is needed to > > actually exercise all the error paths. > > This is left as exercise for the maintainers. > > > > Signed-off-by: Stephen Hemminger > > --- > > drivers/net/mlx5/mlx5_trigger.c | 26 +++++++++++++------------- > > 1 file changed, 13 insertions(+), 13 deletions(-) > > > > diff --git a/drivers/net/mlx5/mlx5_trigger.c > > b/drivers/net/mlx5/mlx5_trigger.c index e2a9bb703261..79a7b233986a > > 100644 > > --- a/drivers/net/mlx5/mlx5_trigger.c > > +++ b/drivers/net/mlx5/mlx5_trigger.c > > @@ -171,42 +171,42 @@ mlx5_dev_start(struct rte_eth_dev *dev) > > if (ret) { > > DRV_LOG(ERR, "port %u Rx queue allocation failed: %s", > > dev->data->port_id, strerror(rte_errno)); > > - mlx5_txq_stop(dev); > > - return -rte_errno; > > + goto error_txq_stop; > > } > > - dev->data->dev_started = 1; > > + > > ret = mlx5_rx_intr_vec_enable(dev); > > if (ret) { > > DRV_LOG(ERR, "port %u Rx interrupt vector creation failed", > > dev->data->port_id); > > - goto error; > > + goto error_rxq_stop; > > } > > mlx5_xstats_init(dev); > > ret = mlx5_traffic_enable(dev); > > if (ret) { > > DRV_LOG(DEBUG, "port %u failed to set defaults flows", > > dev->data->port_id); > > - goto error; > > + goto error_intr_vec_disable; > > } > > ret = mlx5_flow_start(dev, &priv->flows); > > if (ret) { > > DRV_LOG(DEBUG, "port %u failed to set flows", > > dev->data->port_id); > > - goto error; > > + goto error_traffic_disable; > > } > > + > > dev->tx_pkt_burst = mlx5_select_tx_function(dev); > > dev->rx_pkt_burst = mlx5_select_rx_function(dev); > > mlx5_dev_interrupt_handler_install(dev); > > return 0; > > -error: > > - ret = rte_errno; /* Save rte_errno before cleanup. */ > > - /* Rollback. */ > > - dev->data->dev_started = 0; > > - mlx5_flow_stop(dev, &priv->flows); > > + > > +error_traffic_disable: > > mlx5_traffic_disable(dev); > > - mlx5_txq_stop(dev); > > +error_intr_vec_disable: > > + mlx5_rx_intr_vec_disable(dev); > > +error_rxq_stop: > > mlx5_rxq_stop(dev); > > - rte_errno = ret; /* Restore rte_errno. */ > > +error_txq_stop: > > + mlx5_txq_stop(dev); > > return -rte_errno; > > } > > > > -- > > 2.18.0 > The issue was caused in an early version of netvsc VF support where it forgot to call dev_configure on the mlx5 device. In that case mlx5 would get confused and stuck.