[dpdk-dev] [PATCH V12 1/3] eal: add uevent monitor api and callback func

[Wu, Jingjing]

> -----Original Message-----
> From: Guo, Jia
> Sent: Thursday, January 18, 2018 12:12 PM
> To: stephen at networkplumber.org; Richardson, Bruce <bruce.richardson at intel.com>;
> Yigit, Ferruh <ferruh.yigit at intel.com>; gaetan.rivet at 6wind.com
> Cc: Ananyev, Konstantin <konstantin.ananyev at intel.com>; jblunck at infradead.org;
> shreyansh.jain at nxp.com; Wu, Jingjing <jingjing.wu at intel.com>; dev at dpdk.org; Guo, Jia
> <jia.guo at intel.com>; thomas at monjalon.net; Zhang, Helin <helin.zhang at intel.com>;
> motih at mellanox.com
> Subject: [PATCH V12 1/3] eal: add uevent monitor api and callback func
> 
> This patch aim to add a general uevent mechanism in eal device layer,
> to enable all linux kernel object uevent monitoring, user could use these
> APIs to monitor and read out the device status info that sent from the
> kernel side, then corresponding to handle it, such as when detect hotplug
> uevent type, user could detach or attach the device, and more it benefit
> to use to do smoothly fail safe work.
> 
> About uevent monitoring:
> a: add one epolling to poll the netlink socket, to monitor the uevent of
>    the device.
> b: add enum of rte_eal_dev_event_type and struct of rte_eal_uevent.
> c: add below APIs in rte eal device layer.
>    rte_dev_callback_register
>    rte_dev_callback_unregister
>    _rte_dev_callback_process
>    rte_dev_event_monitor_start
>    rte_dev_event_monitor_stop
> 
> Signed-off-by: Jeff Guo <jia.guo at intel.com>
> ---
> v12->v11:
> identify null param in callback for monitor all devices uevent
> ---
>  lib/librte_eal/bsdapp/eal/eal_dev.c     |  38 ++++++
>  lib/librte_eal/common/eal_common_dev.c  | 128 ++++++++++++++++++
>  lib/librte_eal/common/include/rte_dev.h | 119 +++++++++++++++++
>  lib/librte_eal/linuxapp/eal/Makefile    |   1 +
>  lib/librte_eal/linuxapp/eal/eal_dev.c   | 223 ++++++++++++++++++++++++++++++++
>  5 files changed, 509 insertions(+)
>  create mode 100644 lib/librte_eal/bsdapp/eal/eal_dev.c
>  create mode 100644 lib/librte_eal/linuxapp/eal/eal_dev.c
> 

[......]

> +int
> +rte_dev_callback_register(char *device_name, rte_dev_event_cb_fn cb_fn,
> +				void *cb_arg)
> +{
> +	struct rte_dev_event_callback *event_cb = NULL;
> +
> +	rte_spinlock_lock(&rte_dev_event_lock);
> +
> +	if (TAILQ_EMPTY(&(dev_event_cbs)))
> +		TAILQ_INIT(&(dev_event_cbs));
> +
> +	TAILQ_FOREACH(event_cb, &(dev_event_cbs), next) {
> +		if (event_cb->cb_fn == cb_fn &&
> +			event_cb->cb_arg == cb_arg &&
> +			!strcmp(event_cb->dev_name, device_name))
device_name = NULL means means for all devices, right? Can strcmp accept NULL arguments?

> +			break;
> +	}
> +
> +	/* create a new callback. */
> +	if (event_cb == NULL) {
> +		/* allocate a new user callback entity */
> +		event_cb = malloc(sizeof(struct rte_dev_event_callback));
> +		if (event_cb != NULL) {
> +			event_cb->cb_fn = cb_fn;
> +			event_cb->cb_arg = cb_arg;
> +			event_cb->dev_name = device_name;
> +		}
Is that OK to call TAILQ_INSERT_TAIL below if event_cb == NULL?

> +		TAILQ_INSERT_TAIL(&(dev_event_cbs), event_cb, next);
> +	}
> +
> +	rte_spinlock_unlock(&rte_dev_event_lock);
> +	return (event_cb == NULL) ? -1 : 0;
> +}
> +
> +int
> +rte_dev_callback_unregister(char *device_name, rte_dev_event_cb_fn cb_fn,
> +				void *cb_arg)
> +{
> +	int ret;
> +	struct rte_dev_event_callback *event_cb, *next;
> +
> +	if (!cb_fn || device_name == NULL)
> +		return -EINVAL;
> +
> +	rte_spinlock_lock(&rte_dev_event_lock);
> +
> +	ret = 0;
> +
> +	for (event_cb = TAILQ_FIRST(&(dev_event_cbs)); event_cb != NULL;
> +	      event_cb = next) {
> +
> +		next = TAILQ_NEXT(event_cb, next);
> +
> +		if (event_cb->cb_fn != cb_fn ||
> +				(event_cb->cb_arg != (void *)-1 &&
> +				event_cb->cb_arg != cb_arg) ||
> +				strcmp(event_cb->dev_name, device_name))

The same comments as above.

> +			continue;
> +
> +		/*
> +		 * if this callback is not executing right now,
> +		 * then remove it.
> +		 */
> +		if (event_cb->active == 0) {
> +			TAILQ_REMOVE(&(dev_event_cbs), event_cb, next);
> +			rte_free(event_cb);
> +		} else {
> +			ret = -EAGAIN;
> +		}
> +	}
> +
> +	rte_spinlock_unlock(&rte_dev_event_lock);
> +	return ret;
> +}
> +

[......]

> +int
> +rte_dev_event_monitor_start(void)
> +{
> +	int ret;
> +	struct rte_service_spec service;
> +	uint32_t id;
> +	const uint32_t sid = 0;
> +
> +	if (!service_no_init)
> +		return 0;
> +
> +	uint32_t slcore_1 = rte_get_next_lcore(/* start core */ -1,
> +					       /* skip master */ 1,
> +					       /* wrap */ 0);
> +
> +	ret = rte_service_lcore_add(slcore_1);
> +	if (ret) {
> +		RTE_LOG(ERR, EAL, "dev event monitor lcore add fail");
> +		return ret;
> +	}
> +
> +	memset(&service, 0, sizeof(service));
> +	snprintf(service.name, sizeof(service.name), DEV_EV_MNT_SERVICE_NAME);
> +
> +	service.socket_id = rte_socket_id();
> +	service.callback = dev_uev_monitoring;
> +	service.callback_userdata = NULL;
> +	service.capabilities = 0;
> +	ret = rte_service_component_register(&service, &id);
> +	if (ret) {
> +		RTE_LOG(ERR, EAL, "Failed to register service %s "
> +			"err = %" PRId32,
> +			service.name, ret);
> +		return ret;
> +	}
> +	ret = rte_service_runstate_set(sid, 1);
> +	if (ret) {
> +		RTE_LOG(ERR, EAL, "Failed to set the runstate of "
> +			"the service");
Any rollback need to be done when fails?

> +		return ret;
> +	}
> +	ret = rte_service_component_runstate_set(id, 1);
> +	if (ret) {
> +		RTE_LOG(ERR, EAL, "Failed to set the backend runstate"
> +			" of a component");
> +		return ret;
> +	}
> +	ret = rte_service_map_lcore_set(sid, slcore_1, 1);
> +	if (ret) {
> +		RTE_LOG(ERR, EAL, "Failed to enable lcore 1 on "
> +			"dev event monitor service");
> +		return ret;
> +	}
> +	rte_service_lcore_start(slcore_1);
> +	service_no_init = false;
> +	return 0;
> +}
> +
> +int
> +rte_dev_event_monitor_stop(void)
> +{
> +	service_exit = true;
> +	service_no_init = true;
> +	return 0;

Are start and stop peer functions to call? If we call rte_dev_event_monitor_start to start monitor and then call rte_dev_event_monitor_stop to stop it, and then how to start again?

> +}
> --
> 2.7.4