[dpdk-dev] [RFC] ethdev: complete closing to free all resources

[Andrew Rybchenko]

On 09/08/2018 02:39 AM, Thomas Monjalon wrote:
> After closing a port, it cannot be restarted.
> So there is no reason to not free all associated resources.
>
> The last step was done with rte_eth_dev_detach() which is deprecated.
> Instead of removing the associated rte_device, the driver should check
> if no more port (ethdev, cryptodev, etc) is still open for the device.
> Then the device resources can be freed by the driver inside the
> dev_close() driver callback operation.
>
> The last ethdev freeing (dev_private and final release), which were done
> by rte_eth_dev_detach(), are now done at the end of rte_eth_dev_close().

For me, it sounds more logical to kill dev_close and keep detach.
IMHO, dev_close is artificial and hardly useful. detach is a local pair 
to attach.

Anyway it requires update of all drivers as I understand.

> Signed-off-by: Thomas Monjalon <thomas at monjalon.net>
> ---
> This patch contains only the change in the close function as RFC.
>
> This idea was presented at Dublin during the "hotplug talk".
> ---
>   lib/librte_ethdev/rte_ethdev.c | 5 +++++
>   lib/librte_ethdev/rte_ethdev.h | 5 +++--
>   2 files changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c
> index 4c3202505..071fcbd23 100644
> --- a/lib/librte_ethdev/rte_ethdev.c
> +++ b/lib/librte_ethdev/rte_ethdev.c
> @@ -1358,6 +1358,7 @@ void
>   rte_eth_dev_close(uint16_t port_id)
>   {
>   	struct rte_eth_dev *dev;
> +	struct rte_bus *bus;
>   
>   	RTE_ETH_VALID_PORTID_OR_RET(port_id);
>   	dev = &rte_eth_devices[port_id];
> @@ -1372,6 +1373,10 @@ rte_eth_dev_close(uint16_t port_id)
>   	dev->data->nb_tx_queues = 0;
>   	rte_free(dev->data->tx_queues);
>   	dev->data->tx_queues = NULL;
> +
> +	rte_free(dev->data->dev_private);
> +
> +	rte_eth_dev_release_port(dev);
>   }
>   
>   int
> diff --git a/lib/librte_ethdev/rte_ethdev.h b/lib/librte_ethdev/rte_ethdev.h
> index 7070e9ab4..37a757a7a 100644
> --- a/lib/librte_ethdev/rte_ethdev.h
> +++ b/lib/librte_ethdev/rte_ethdev.h
> @@ -1797,8 +1797,9 @@ int rte_eth_dev_set_link_down(uint16_t port_id);
>   
>   /**
>    * Close a stopped Ethernet device. The device cannot be restarted!
> - * The function frees all resources except for needed by the
> - * closed state. To free these resources, call rte_eth_dev_detach().
> + * The function frees all port resources.
> + * If there is no more port associated with the underlying device,
> + * the driver should free the device resources.
>    *
>    * @param port_id
>    *   The port identifier of the Ethernet device.