On 2023/2/22 1:00, Stephen Hemminger wrote:
> On Tue, 21 Feb 2023 07:24:19 +0000
> Ruifeng Wang <ruifeng.w...@arm.com> wrote:
>
>>> -----Original Message-----
>>> From: fengchengwen <fengcheng...@huawei.com>
>>> Sent: Monday, February 20, 2023 2:58 PM
>>> To: Ashok Kaladi <ashok.k.kal...@intel.com>; jer...@marvell.com;
>>> tho...@monjalon.net
>>> Cc: dev@dpdk.org; s.v.naga.haris...@intel.com; erik.g.carri...@intel.com;
>>> abhinandan.guj...@intel.com; sta...@dpdk.org; Ruifeng Wang
>>> <ruifeng.w...@arm.com>
>>> Subject: Re: [PATCH 2/2] ethdev: fix race condition in fast-path ops setup
>>>
>>> On 2023/2/20 14:08, Ashok Kaladi wrote:
>>>> If ethdev enqueue or dequeue function is called during
>>>> eth_dev_fp_ops_setup(), it may get pre-empted after setting the
>>>> function pointers, but before setting the pointer to port data.
>>>> In this case the newly registered enqueue/dequeue function will use
>>>> dummy port data and end up in seg fault.
>>>>
>>>> This patch moves the updation of each data pointers before updating
>>>> corresponding function pointers.
>>>>
>>>> Fixes: c87d435a4d79 ("ethdev: copy fast-path API into separate
>>>> structure")
>>>> Cc: sta...@dpdk.org
>
> Why is something calling enqueue/dequeue when device is not fully started.
> A correctly written application would not call rx/tx burst until after
> ethdev start had finished.
Please refer the eb0d471a894 (ethdev: add proactive error handling mode), when
driver
recover itself, the application may still invoke enqueue/dequeue API.
>
> Would something like this work better?
>
> Note: there is another bug in current code. The check for link state interrupt
> and link_ops could return -ENOTSUP and leave device in indeterminate state.
> The check should be done before calling PMD.
>
> diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c
> index 0266cc82acb6..d6c163ed85e7 100644
> --- a/lib/ethdev/rte_ethdev.c
> +++ b/lib/ethdev/rte_ethdev.c
> @@ -1582,6 +1582,14 @@ rte_eth_dev_start(uint16_t port_id)
> return 0;
> }
>
> + if (dev->data->dev_conf.intr_conf.lsc == 0 &&
> + dev->dev_ops->link_update == NULL) {
> + RTE_ETHDEV_LOG(INFO,
> + "Device with port_id=%"PRIu16" link update not
> supported\n",
> + port_id);
> + return -ENOTSUP;
> + }
> +
> ret = rte_eth_dev_info_get(port_id, &dev_info);
> if (ret != 0)
> return ret;
> @@ -1591,9 +1599,7 @@ rte_eth_dev_start(uint16_t port_id)
> eth_dev_mac_restore(dev, &dev_info);
>
> diag = (*dev->dev_ops->dev_start)(dev);
> - if (diag == 0)
> - dev->data->dev_started = 1;
> - else
> + if (diag != 0)
> return eth_err(port_id, diag);
>
> ret = eth_dev_config_restore(dev, &dev_info, port_id);
> @@ -1611,16 +1617,18 @@ rte_eth_dev_start(uint16_t port_id)
> return ret;
> }
>
> - if (dev->data->dev_conf.intr_conf.lsc == 0) {
> - if (*dev->dev_ops->link_update == NULL)
> - return -ENOTSUP;
> - (*dev->dev_ops->link_update)(dev, 0);
> - }
> -
> /* expose selection of PMD fast-path functions */
> eth_dev_fp_ops_setup(rte_eth_fp_ops + port_id, dev);
>
> + /* ensure state is set before marking device ready */
> + rte_smp_wmb();
> +
> rte_ethdev_trace_start(port_id);
> +
> + /* Update current link state */
> + if (dev->data->dev_conf.intr_conf.lsc == 0)
> + (*dev->dev_ops->link_update)(dev, 0);
> +
> return 0;
> }
>
>
> .
>
