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
>
> Signed-off-by: Ashok Kaladi <ashok.k.kal...@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;
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.
> }
>
>
