Re: [dpdk-dev] [PATCH v2] ethdev: fix multi-process NULL dereference crashes

[Thomas Monjalon <thomas.monjalon@6wind.com>]

2017-01-24 15:01, Remy Horton:
> Secondary processes were blanket zeroing ethernet device memory,
> resulting in NULL dereference crashes in multi-process setups.
> 
> Fixes: 7f95f78a8aea ("ethdev: clear data when allocating device")
> 
> Signed-off-by: Remy Horton <remy.horton@intel.com>
> ---
>  doc/guides/rel_notes/release_17_02.rst | 5 +++++
>  lib/librte_ether/rte_ethdev.c          | 4 +++-
>  2 files changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/doc/guides/rel_notes/release_17_02.rst b/doc/guides/rel_notes/release_17_02.rst
> index 0ecd720..1472f84 100644
> --- a/doc/guides/rel_notes/release_17_02.rst
> +++ b/doc/guides/rel_notes/release_17_02.rst
> @@ -222,6 +222,11 @@ Drivers
>    Fixed few regressions introduced in recent releases that break the virtio
>    multiple process support.
>  
> +* **ethdev: Fixed crash with multi-processing.**
> +
> +  Secondary processes were blanket zeroing ethernet device memory,
> +  resulting in NULL dereference crashes in multi-process setups.

It does not describe exactly the use-case it is fixing (same in commit message).
I guess you saw an issue when creating a vdev in the primary process and
another one in a secondary process, erasing the data of the first one.

nit: ethdev bug should be shown before PMD bugs like virtio one above.

> --- a/lib/librte_ether/rte_ethdev.c
> +++ b/lib/librte_ether/rte_ethdev.c
> @@ -225,8 +225,10 @@ rte_eth_dev_allocate(const char *name)
>  		return NULL;
>  	}
>  
> -	memset(&rte_eth_dev_data[port_id], 0, sizeof(struct rte_eth_dev_data));
>  	eth_dev = eth_dev_get(port_id);
> +	if (rte_eal_process_type() == RTE_PROC_PRIMARY)
> +		memset(&rte_eth_dev_data[port_id], 0,
> +			sizeof(struct rte_eth_dev_data));

My previous proposal was:
	memset(eth_dev->data, 0, sizeof(*eth_dev->data))
It is better to avoid reference to the global array rte_eth_dev_data.

Anyway, the shared data are still overwritten for the name, the port id
and the MTU.
Please describe the exact case where it is working for you.