Re: [dpdk-dev] [dpdk-stable] [PATCH] net/iavf: fix multi-process shared data

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 9/28/2021 4:37 AM, dapengx.yu@intel.com wrote:
> From: Dapeng Yu <dapengx.yu@intel.com>
> 
> When the iavf_adapter instance is not initialized completedly in the
> primary process, the secondary process accesses its "rte_eth_dev"
> member, it causes secondary process crash.
> 
> This patch replaces adapter->eth_dev with rte_eth_devices[port_id] in
> the data paths where rte_eth_dev instance is accessed.
> 
> Fixes: f978c1c9b3b5 ("net/iavf: add RSS hash parsing in AVX path")
> Fixes: 9c9aa0040344 ("net/iavf: add offload path for Rx AVX512 flex descriptor")
> Fixes: 63660ea3ee0b ("net/iavf: add RSS hash parsing in SSE path")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Dapeng Yu <dapengx.yu@intel.com>
> ---
>  drivers/net/iavf/iavf_rxtx_vec_avx2.c   | 5 +++--
>  drivers/net/iavf/iavf_rxtx_vec_avx512.c | 5 +++--
>  drivers/net/iavf/iavf_rxtx_vec_sse.c    | 3 ++-
>  3 files changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/iavf/iavf_rxtx_vec_avx2.c b/drivers/net/iavf/iavf_rxtx_vec_avx2.c
> index 475070e036..59b086ade5 100644
> --- a/drivers/net/iavf/iavf_rxtx_vec_avx2.c
> +++ b/drivers/net/iavf/iavf_rxtx_vec_avx2.c
> @@ -525,6 +525,7 @@ _iavf_recv_raw_pkts_vec_avx2_flex_rxd(struct iavf_rx_queue *rxq,
>  #define IAVF_DESCS_PER_LOOP_AVX 8
>  
>  	const uint32_t *type_table = rxq->vsi->adapter->ptype_tbl;
> +	struct rte_eth_dev *dev = &rte_eth_devices[rxq->port_id];
>  

It is not good idea to access global variable directly from the driver.

The problem definition is correct, eth_dev is unique per process, so it can't be
saved to a shared struct.

But here I assume real intention is to be able to access PMD specific data from
queue struct, for this what about storing 'rte_eth_dev_data' in the
'iavf_rx_queue', this should sove the problem without accessing the global variable.