Re: [PATCH] net/tap: Bug fix to populate fds in secondary process

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

On 11/26/2021 4:15 AM, Kumara Parameshwaran wrote:
> From: Kumara Parameshwaran <kparameshwar@vmware.com>
> 
> When a tap device is hotplugged to primary process which in turn
> adds the device to all secondary process, the secondary process
> does a tap_mp_attach_queues, but the fds are not populated in
> the primary during the probe they are populated during the queue_setup,
> added a fix to sync the queues during rte_eth_dev_start
> 
> Signed-off-by: Kumara Parameshwaran <kparameshwar@vmware.com>

<...>

>   
> +static int
> +tap_mp_req_start_rxtx(const struct rte_mp_msg *request, __rte_unused const void *peer)
> +{
> +	struct rte_eth_dev *dev;
> +	int ret;
> +	uint16_t port_id;
> +	const struct ipc_queues *request_param =
> +		(const struct ipc_queues *)request->param;
> +	int fd_iterator;
> +	int queue;
> +	struct pmd_process_private *process_private;
> +
> +	ret = rte_eth_dev_get_port_by_name(request_param->port_name, &port_id);
> +	if (ret) {
> +		TAP_LOG(ERR, "Failed to get port id for %s",
> +			request_param->port_name);
> +		return -1;
> +	}
> +	dev = &rte_eth_devices[port_id];

Since this is not really related with your patch, I want to have a separate thread for it.

It is not good to access the 'rte_eth_devices' global variable directly from a driver, that
is error prone.

Btw, what 'peer' supposed to contain?

It can be solved by adding an internal API, only for drivers to get eth_dev from the name,
like: 'rte_eth_dev_get_by_name()'.
This way a few other usage can be converted to this API.

@Thomas and @Andrew what do you think about the new API proposal?