From: fengchengwen <fengchengwen@huawei.com>
To: Ashok Kaladi <ashok.k.kaladi@intel.com>, <jerinj@marvell.com>,
<thomas@monjalon.net>
Cc: <dev@dpdk.org>, <s.v.naga.harish.k@intel.com>,
<erik.g.carrillo@intel.com>, <abhinandan.gujjar@intel.com>,
<stable@dpdk.org>
Subject: Re: [PATCH 2/2] ethdev: fix race condition in fast-path ops setup
Date: Mon, 20 Feb 2023 15:01:34 +0800 [thread overview]
Message-ID: <970123b7-23ca-616e-bf5a-a04578db65dc@huawei.com> (raw)
In-Reply-To: <20230220060839.1267349-2-ashok.k.kaladi@intel.com>
Sorry resend, because forget one line.
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: stable@dpdk.org
>
> Signed-off-by: Ashok Kaladi <ashok.k.kaladi@intel.com>
>
> diff --git a/lib/ethdev/ethdev_private.c b/lib/ethdev/ethdev_private.c
> index 48090c879a..a0232c669f 100644
> --- a/lib/ethdev/ethdev_private.c
> +++ b/lib/ethdev/ethdev_private.c
> @@ -270,17 +270,17 @@ void
> eth_dev_fp_ops_setup(struct rte_eth_fp_ops *fpo,
> const struct rte_eth_dev *dev)
> {
> + fpo->rxq.data = dev->data->rx_queues;
> fpo->rx_pkt_burst = dev->rx_pkt_burst;
> + fpo->txq.data = dev->data->tx_queues;
> fpo->tx_pkt_burst = dev->tx_pkt_burst;
> fpo->tx_pkt_prepare = dev->tx_pkt_prepare;
> fpo->rx_queue_count = dev->rx_queue_count;
> fpo->rx_descriptor_status = dev->rx_descriptor_status;
> fpo->tx_descriptor_status = dev->tx_descriptor_status;
>
> - fpo->rxq.data = dev->data->rx_queues;
> fpo->rxq.clbk = (void **)(uintptr_t)dev->post_rx_burst_cbs;
>
> - fpo->txq.data = dev->data->tx_queues;
> fpo->txq.clbk = (void **)(uintptr_t)dev->pre_tx_burst_cbs;
Hi Ashok,
The modification is OK for the x86 platform (which has strong memory order, and will keep write-after-write order in here, and read-after-read in rte_eth_rx/tx_burst),
but for other weak memory order (like ARM platform) will fail.
For the weak memory order, suggest add write-mb in here, and read-mb in rte_eth_rx/tx_burst.
But the read-mb in rte_eth_rx/tx_burst will affect performance, especially the variable will changes only once when start.
So I suggest use write-mb + delay in here:
fpo->rxq.data = dev->data->rx_queues;
fpo->txq.data = dev->data->tx_queues;
wmb();
mdelay(5); // delay e.g. 5ms
fpo->rx_pkt_burst = dev->rx_pkt_burst;
fpo->tx_pkt_burst = dev->tx_pkt_burst;
And also cc ARMv8 maintainer.
> }
>
>
next prev parent reply other threads:[~2023-02-20 7:01 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-20 6:08 [PATCH 1/2] eventdev: fix race condition in fast-path set function Ashok Kaladi
2023-02-20 6:08 ` [PATCH 2/2] ethdev: fix race condition in fast-path ops setup Ashok Kaladi
2023-02-20 6:57 ` fengchengwen
2023-02-21 7:24 ` Ruifeng Wang
2023-02-21 17:00 ` Stephen Hemminger
2023-02-22 1:07 ` fengchengwen
2023-02-22 9:41 ` Ruifeng Wang
2023-02-22 10:41 ` Konstantin Ananyev
2023-02-22 22:48 ` Honnappa Nagarahalli
2023-02-23 1:15 ` Stephen Hemminger
2023-02-23 4:47 ` Honnappa Nagarahalli
2023-02-23 4:40 ` Honnappa Nagarahalli
2023-02-23 8:23 ` fengchengwen
2023-02-23 13:31 ` Konstantin Ananyev
2023-02-25 1:32 ` fengchengwen
2023-02-28 23:57 ` Honnappa Nagarahalli
2023-02-20 7:01 ` fengchengwen [this message]
2023-02-20 9:44 ` Konstantin Ananyev
2023-03-03 16:49 ` Ferruh Yigit
-- strict thread matches above, loose matches on Subject: below --
2023-02-20 6:06 [PATCH 1/2] eventdev: fix race condition in fast-path set function Ashok Kaladi
2023-02-20 6:06 ` [PATCH 2/2] ethdev: fix race condition in fast-path ops setup Ashok Kaladi
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