Re: [dpdk-dev] [PATCH v4 1/4] ethdev: Add API to enable device event handler

[Andrew Rybchenko <arybchenko@solarflare.com>]

On 10.07.2018 15:51, Jeff Guo wrote:
> Implement a couple of eal device event handler install/uninstall APIs
> in ethdev, it could let PMDs have chance to manage the eal device event,
> such as register device event callback, then monitor and process the
> hotplug event.

I think it is moving in right direction, but my problem with the patch is
that I don't understand what prevents us to make it even more generic.
Right now it looks like that PCI driver flag RTE_PCI_DRV_INTR_RMV is
sufficient and everything else could be done on ethdev layer.
RTE_PCI_DRV_INTR_RMV  is mapped to RTE_ETH_DEV_INTR_RMV eth
device flag. The flag may be used as an indication in rte_eth_dev_create()
to register the callback.
May be I'm completely wrong above, but if so, I'd like to understand why
and prefer to see explanations in the patch description.

> Signed-off-by: Jeff Guo <jia.guo@intel.com>
> ---
> v4->v3:
> change to use eal device event handler install api
> ---
>   doc/guides/rel_notes/release_18_08.rst | 12 +++++++
>   lib/librte_ethdev/rte_ethdev.c         | 59 ++++++++++++++++++++++++++++++++++
>   lib/librte_ethdev/rte_ethdev_driver.h  | 32 ++++++++++++++++++
>   3 files changed, 103 insertions(+)
>
> diff --git a/doc/guides/rel_notes/release_18_08.rst b/doc/guides/rel_notes/release_18_08.rst
> index bc01242..b6482ce 100644
> --- a/doc/guides/rel_notes/release_18_08.rst
> +++ b/doc/guides/rel_notes/release_18_08.rst
> @@ -46,6 +46,18 @@ New Features
>     Flow API support has been added to CXGBE Poll Mode Driver to offload
>     flows to Chelsio T5/T6 NICs.
>   
> +* **Added eal device event process helper in ethdev.**
> +
> +  Implement a couple of eal device event handler install/uninstall APIs in
> +  ethdev, these helper could let PMDs have chance to manage the eal device
> +  event, such as register device event callback, then monitor and process
> +  hotplug event.
> +
> +  * ``rte_eth_dev_event_handler_install`` for PMDs use to install the device
> +    event handler.
> +  * ``rte_eth_dev_event_handler_uninstall`` for PMDs use to uninstall the device
> +    event handler.
> +
>   
>   API Changes
>   -----------
> diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c
> index a9977df..09ea02d 100644
> --- a/lib/librte_ethdev/rte_ethdev.c
> +++ b/lib/librte_ethdev/rte_ethdev.c
> @@ -4518,6 +4518,65 @@ rte_eth_devargs_parse(const char *dargs, struct rte_eth_devargs *eth_da)
>   	return result;
>   }
>   
> +static void __rte_experimental
> +eth_dev_event_callback(char *device_name, enum rte_dev_event_type type,
> +			     void *arg)
> +{
> +	struct rte_eth_dev *eth_dev = (struct rte_eth_dev *)arg;
> +
> +	switch (type) {
> +	case RTE_DEV_EVENT_REMOVE:
> +		ethdev_log(INFO, "The device: %s has been removed!\n",

Colon after 'device' above looks strange for me. I'd suggest to remove it.
If so, similar below for ADD.

> +			    device_name);
> +
> +		if (!device_name || !eth_dev)
> +			return;
> +
> +		if (!(eth_dev->data->dev_flags & RTE_ETH_EVENT_INTR_RMV))

It looks like a typo above. Shouldn't it be RTE_ETH_DEV_INTR_RMV?

> +			return;
> +
> +		if (!strcmp(device_name, eth_dev->device->name))
> +			_rte_eth_dev_callback_process(eth_dev,
> +						      RTE_ETH_EVENT_INTR_RMV,
> +						      NULL);
> +		break;
> +	case RTE_DEV_EVENT_ADD:
> +		ethdev_log(INFO, "The device: %s has been added!\n",
> +			device_name);
> +		break;
> +	default:
> +		break;
> +	}
> +}
> +
> +int __rte_experimental
> +rte_eth_dev_event_handler_install(struct rte_eth_dev *eth_dev)
> +{
> +	int result = 0;
> +
> +	result = rte_dev_event_callback_register(eth_dev->device->name,
> +					eth_dev_event_callback, eth_dev);
> +	if (result)
> +		RTE_LOG(ERR, EAL, "device event callback register failed for "
> +			"device:%s!\n", eth_dev->device->name);

Why ethdev_log() is used above, but here is RTE_LOG with EAL?
Similar question below.

> +
> +	return result;
> +}
> +
> +int __rte_experimental
> +rte_eth_dev_event_handler_uninstall(struct rte_eth_dev *eth_dev)
> +{
> +	int result = 0;
> +
> +	result = rte_dev_event_callback_unregister(eth_dev->device->name,
> +					eth_dev_event_callback, eth_dev);
> +	if (result)
> +		RTE_LOG(ERR, EAL, "device event callback unregister failed for"
> +			" device:%s!\n", eth_dev->device->name);
> +
> +	return result;
> +}
> +
>   RTE_INIT(ethdev_init_log);
>   static void
>   ethdev_init_log(void)

<...>