Re: [dpdk-dev] [PATCH v4 7/9] eal: add lcore init callbacks

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

 
> diff --git a/lib/librte_eal/common/eal_common_lcore.c b/lib/librte_eal/common/eal_common_lcore.c
> index a61824a779..52c46a4cea 100644
> --- a/lib/librte_eal/common/eal_common_lcore.c
> +++ b/lib/librte_eal/common/eal_common_lcore.c
> @@ -224,11 +224,114 @@ rte_socket_id_by_idx(unsigned int idx)
>  }
> 
>  static rte_spinlock_t lcore_lock = RTE_SPINLOCK_INITIALIZER;
> +struct lcore_callback {
> +	TAILQ_ENTRY(lcore_callback) next;
> +	char *name;
> +	rte_lcore_init_cb init;
> +	rte_lcore_uninit_cb uninit;
> +	void *arg;
> +};
> +static TAILQ_HEAD(lcore_callbacks_head, lcore_callback) lcore_callbacks =
> +	TAILQ_HEAD_INITIALIZER(lcore_callbacks);
> +
> +static int
> +callback_init(struct lcore_callback *callback, unsigned int lcore_id)
> +{
> +	if (callback->init == NULL)
> +		return 0;
> +	RTE_LOG(DEBUG, EAL, "Call init for lcore callback %s, lcore_id %u\n",
> +		callback->name, lcore_id);
> +	return callback->init(lcore_id, callback->arg);
> +}
> +
> +static void
> +callback_uninit(struct lcore_callback *callback, unsigned int lcore_id)
> +{
> +	if (callback->uninit == NULL)
> +		return;
> +	RTE_LOG(DEBUG, EAL, "Call uninit for lcore callback %s, lcore_id %u\n",
> +		callback->name, lcore_id);
> +	callback->uninit(lcore_id, callback->arg);
> +}
> +
> +void *
> +rte_lcore_callback_register(const char *name, rte_lcore_init_cb init,
> +	rte_lcore_uninit_cb uninit, void *arg)
> +{
> +	struct rte_config *cfg = rte_eal_get_configuration();
> +	struct lcore_callback *callback;
> +	unsigned int lcore_id;
> +
> +	callback = calloc(1, sizeof(*callback));
> +	if (callback == NULL)
> +		return NULL;
> +	if (asprintf(&callback->name, "%s-%p", name, arg) == -1) {

If name is null, I presume asprintf() would segfault, right?
As this is a public (and control-plane) API, I think it is worth to
add formal checking for input parameters.
Same for other new public functions. 

> +		free(callback);
> +		return NULL;
> +	}
> +	callback->init = init;
> +	callback->uninit = uninit;
> +	callback->arg = arg;
> +	rte_spinlock_lock(&lcore_lock);
> +	if (callback->init == NULL)
> +		goto no_init;
> +	for (lcore_id = 0; lcore_id < RTE_MAX_LCORE; lcore_id++) {
> +		if (cfg->lcore_role[lcore_id] == ROLE_OFF)
> +			continue;
> +		if (callback_init(callback, lcore_id) == 0)
> +			continue;
> +		/* Callback refused init for this lcore, uninitialize all
> +		 * previous lcore.
> +		 */
> +		for (; lcore_id != 0; lcore_id--) {
> +			if (cfg->lcore_role[lcore_id - 1] == ROLE_OFF)
> +				continue;
> +			callback_uninit(callback, lcore_id - 1);
> +		}

Just as a nit, you can do here instead:
while (lcore_id-- != 0) { if (cfg->lcore_role[lcore_id] == ROLE_OFF) ...}
To avoid 'lcore_id -1' inside loop body.
Might look a bit nicer.

> +		free(callback);

I think you forgot:
free(callback->name);
here.
Might be worth to have a separate helper function around these 2 frees.

> +		callback = NULL;
> +		goto out;
> +	}
> +no_init:
> +	TAILQ_INSERT_TAIL(&lcore_callbacks, callback, next);
> +	RTE_LOG(DEBUG, EAL, "Registered new lcore callback %s (%sinit, %suninit).\n",
> +		callback->name, callback->init == NULL ? "NO " : "",
> +		callback->uninit == NULL ? "NO " : "");
> +out:
> +	rte_spinlock_unlock(&lcore_lock);
> +	return callback;
> +}
> +
> +void
> +rte_lcore_callback_unregister(void *handle)
> +{
> +	struct rte_config *cfg = rte_eal_get_configuration();
> +	struct lcore_callback *callback = handle;
> +	unsigned int lcore_id;
> +
> +	rte_spinlock_lock(&lcore_lock);
> +	if (callback->uninit == NULL)
> +		goto no_uninit;
> +	for (lcore_id = 0; lcore_id < RTE_MAX_LCORE; lcore_id++) {
> +		if (cfg->lcore_role[lcore_id] == ROLE_OFF)
> +			continue;
> +		callback_uninit(callback, lcore_id);
> +	}
> +no_uninit:
> +	TAILQ_REMOVE(&lcore_callbacks, callback, next);
> +	rte_spinlock_unlock(&lcore_lock);
> +	RTE_LOG(DEBUG, EAL, "Unregistered lcore callback %s-%p.\n",
> +		callback->name, callback->arg);
> +	free(callback->name);
> +	free(callback);
> +}
> 
>  unsigned int
>  eal_lcore_non_eal_allocate(void)
>  {
>  	struct rte_config *cfg = rte_eal_get_configuration();
> +	struct lcore_callback *callback;
> +	struct lcore_callback *prev;
>  	unsigned int lcore_id;
> 
>  	if (cfg->process_type == RTE_PROC_SECONDARY ||
> @@ -244,8 +347,29 @@ eal_lcore_non_eal_allocate(void)
>  		cfg->lcore_count++;
>  		break;
>  	}
> -	if (lcore_id == RTE_MAX_LCORE)
> +	if (lcore_id == RTE_MAX_LCORE) {
>  		RTE_LOG(DEBUG, EAL, "No lcore available.\n");
> +		goto out;
> +	}
> +	TAILQ_FOREACH(callback, &lcore_callbacks, next) {
> +		if (callback_init(callback, lcore_id) == 0)
> +			continue;
> +		/* Callback refused init for this lcore, call uninit for all
> +		 * previous callbacks.
> +		 */
> +		prev = TAILQ_PREV(callback, lcore_callbacks_head, next);
> +		while (prev != NULL) {
> +			callback_uninit(prev, lcore_id);
> +			prev = TAILQ_PREV(prev, lcore_callbacks_head, next);
> +		}
> +		RTE_LOG(DEBUG, EAL, "Initialization refused for lcore %u.\n",
> +			lcore_id);
> +		cfg->lcore_role[lcore_id] = ROLE_OFF;
> +		cfg->lcore_count--;
> +		lcore_id = RTE_MAX_LCORE;
> +		goto out;
> +	}
> +out:
>  	rte_spinlock_unlock(&lcore_lock);
>  	return lcore_id;
>  }
> @@ -254,11 +378,15 @@ void
>  eal_lcore_non_eal_release(unsigned int lcore_id)
>  {
>  	struct rte_config *cfg = rte_eal_get_configuration();
> +	struct lcore_callback *callback;
> 
>  	rte_spinlock_lock(&lcore_lock);
> -	if (cfg->lcore_role[lcore_id] == ROLE_NON_EAL) {
> -		cfg->lcore_role[lcore_id] = ROLE_OFF;
> -		cfg->lcore_count--;
> -	}
> +	if (cfg->lcore_role[lcore_id] != ROLE_NON_EAL)
> +		goto out;
> +	TAILQ_FOREACH(callback, &lcore_callbacks, next)
> +		callback_uninit(callback, lcore_id);
> +	cfg->lcore_role[lcore_id] = ROLE_OFF;
> +	cfg->lcore_count--;
> +out:
>  	rte_spinlock_unlock(&lcore_lock);
>  }