Date:   Fri, 15 Jan 2021 18:03:19 +0200
From:   Ido Schimmel <idosch@...sch.org>
To:     Jiri Pirko <jiri@...nulli.us>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, kuba@...nel.org,
        jacob.e.keller@...el.com, roopa@...dia.com, mlxsw@...dia.com
Subject: Re: [patch net-next RFC 02/10] devlink: implement line card
 provisioning

On Wed, Jan 13, 2021 at 01:12:14PM +0100, Jiri Pirko wrote:
> From: Jiri Pirko <jiri@...dia.com>
> 
> In order to be able to configure all needed stuff on a port/netdevice
> of a line card without the line card being present, introduce line card
> provisioning. Basically provisioning will create a placeholder for
> instances (ports/netdevices) for a line card type.
> 
> Allow the user to query the supported line card types over line card
> get command. Then implement two netlink commands to allow user to
> provision/unprovision the line card with selected line card type.
> 
> On the driver API side, add provision/unprovision ops and supported
> types array to be advertised. Upon provision op call, the driver should
> take care of creating the instances for the particular line card type.
> Introduce provision_set/clear() functions to be called by the driver
> once the provisioning/unprovisioning is done on its side.
> 
> Signed-off-by: Jiri Pirko <jiri@...dia.com>
> ---
>  include/net/devlink.h        |  31 +++++++-
>  include/uapi/linux/devlink.h |  17 +++++
>  net/core/devlink.c           | 141 ++++++++++++++++++++++++++++++++++-
>  3 files changed, 185 insertions(+), 4 deletions(-)
> 
> diff --git a/include/net/devlink.h b/include/net/devlink.h
> index 67c2547d5ef9..854abd53e9ea 100644
> --- a/include/net/devlink.h
> +++ b/include/net/devlink.h
> @@ -139,10 +139,33 @@ struct devlink_port {
>  	struct mutex reporters_lock; /* Protects reporter_list */
>  };
>  
> +struct devlink_linecard_ops;
> +
>  struct devlink_linecard {
>  	struct list_head list;
>  	struct devlink *devlink;
>  	unsigned int index;
> +	const struct devlink_linecard_ops *ops;
> +	void *priv;
> +	enum devlink_linecard_state state;
> +	const char *provisioned_type;
> +};
> +
> +/**
> + * struct devlink_linecard_ops - Linecard operations
> + * @supported_types: array of supported types of linecards
> + * @supported_types_count: number of elements in the array above
> + * @provision: callback to provision the linecard slot with certain
> + *	       type of linecard
> + * @unprovision: callback to unprovision the linecard slot
> + */
> +struct devlink_linecard_ops {
> +	const char **supported_types;
> +	unsigned int supported_types_count;
> +	int (*provision)(struct devlink_linecard *linecard, void *priv,
> +			 u32 type_index, struct netlink_ext_ack *extack);
> +	int (*unprovision)(struct devlink_linecard *linecard, void *priv,
> +			   struct netlink_ext_ack *extack);
>  };
>  
>  struct devlink_sb_pool_info {
> @@ -1414,9 +1437,13 @@ void devlink_port_attrs_pci_pf_set(struct devlink_port *devlink_port, u32 contro
>  				   u16 pf, bool external);
>  void devlink_port_attrs_pci_vf_set(struct devlink_port *devlink_port, u32 controller,
>  				   u16 pf, u16 vf, bool external);
> -struct devlink_linecard *devlink_linecard_create(struct devlink *devlink,
> -						 unsigned int linecard_index);
> +struct devlink_linecard *
> +devlink_linecard_create(struct devlink *devlink, unsigned int linecard_index,
> +			const struct devlink_linecard_ops *ops, void *priv);
>  void devlink_linecard_destroy(struct devlink_linecard *linecard);
> +void devlink_linecard_provision_set(struct devlink_linecard *linecard,
> +				    u32 type_index);
> +void devlink_linecard_provision_clear(struct devlink_linecard *linecard);
>  int devlink_sb_register(struct devlink *devlink, unsigned int sb_index,
>  			u32 size, u16 ingress_pools_count,
>  			u16 egress_pools_count, u16 ingress_tc_count,
> diff --git a/include/uapi/linux/devlink.h b/include/uapi/linux/devlink.h
> index e5ed0522591f..4111ddcc000b 100644
> --- a/include/uapi/linux/devlink.h
> +++ b/include/uapi/linux/devlink.h
> @@ -131,6 +131,9 @@ enum devlink_command {
>  	DEVLINK_CMD_LINECARD_NEW,
>  	DEVLINK_CMD_LINECARD_DEL,
>  
> +	DEVLINK_CMD_LINECARD_PROVISION,
> +	DEVLINK_CMD_LINECARD_UNPROVISION,

I do not really see the point in these two commands. Better extend
DEVLINK_CMD_LINECARD_SET to carry these attributes.

> +
>  	/* add new commands above here */
>  	__DEVLINK_CMD_MAX,
>  	DEVLINK_CMD_MAX = __DEVLINK_CMD_MAX - 1
> @@ -329,6 +332,17 @@ enum devlink_reload_limit {
>  
>  #define DEVLINK_RELOAD_LIMITS_VALID_MASK (_BITUL(__DEVLINK_RELOAD_LIMIT_MAX) - 1)
>  
> +enum devlink_linecard_state {
> +	DEVLINK_LINECARD_STATE_UNSPEC,
> +	DEVLINK_LINECARD_STATE_UNPROVISIONED,
> +	DEVLINK_LINECARD_STATE_UNPROVISIONING,
> +	DEVLINK_LINECARD_STATE_PROVISIONING,

Can you explain why these two states are necessary? Any reason the
provision operation can't be synchronous? This is somewhat explained in
patch #8, but it should really be explained here. Changelog says:

"To avoid deadlock and to mimic actual HW flow, use workqueue
to add/del ports during provisioning as the port add/del calls
devlink_port_register/unregister() which take devlink mutex."

The deadlock is not really a reason to have these states.
'DEVLINK_CMD_PORT_SPLIT' also calls devlink_port_register() /
devlink_port_unregister() and the deadlock is solved by:

'internal_flags = DEVLINK_NL_FLAG_NO_LOCK'

A hardware flow the requires it is something else...

> +	DEVLINK_LINECARD_STATE_PROVISIONED,
> +
> +	__DEVLINK_LINECARD_STATE_MAX,
> +	DEVLINK_LINECARD_STATE_MAX = __DEVLINK_LINECARD_STATE_MAX - 1
> +};
> +
>  enum devlink_attr {
>  	/* don't change the order or add anything between, this is ABI! */
>  	DEVLINK_ATTR_UNSPEC,
> @@ -535,6 +549,9 @@ enum devlink_attr {
>  	DEVLINK_ATTR_RELOAD_ACTION_STATS,       /* nested */
>  
>  	DEVLINK_ATTR_LINECARD_INDEX,		/* u32 */
> +	DEVLINK_ATTR_LINECARD_STATE,		/* u8 */
> +	DEVLINK_ATTR_LINECARD_TYPE,		/* string */
> +	DEVLINK_ATTR_LINECARD_SUPPORTED_TYPES,	/* nested */
>  
>  	/* add new attributes above here, update the policy in devlink.c */
>  
> diff --git a/net/core/devlink.c b/net/core/devlink.c
> index 564e921133cf..434eecc310c3 100644
> --- a/net/core/devlink.c
> +++ b/net/core/devlink.c
> @@ -1192,7 +1192,9 @@ static int devlink_nl_linecard_fill(struct sk_buff *msg,
>  				    u32 seq, int flags,
>  				    struct netlink_ext_ack *extack)
>  {
> +	struct nlattr *attr;
>  	void *hdr;
> +	int i;
>  
>  	hdr = genlmsg_put(msg, portid, seq, &devlink_nl_family, flags, cmd);
>  	if (!hdr)
> @@ -1202,6 +1204,22 @@ static int devlink_nl_linecard_fill(struct sk_buff *msg,
>  		goto nla_put_failure;
>  	if (nla_put_u32(msg, DEVLINK_ATTR_LINECARD_INDEX, linecard->index))
>  		goto nla_put_failure;
> +	if (nla_put_u8(msg, DEVLINK_ATTR_LINECARD_STATE, linecard->state))
> +		goto nla_put_failure;
> +	if (linecard->state >= DEVLINK_LINECARD_STATE_PROVISIONED &&

This assumes that every state added after provisioned should report the
type. Better to check for the specific states

> +	    nla_put_string(msg, DEVLINK_ATTR_LINECARD_TYPE,
> +			   linecard->provisioned_type))
> +		goto nla_put_failure;
> +
> +	attr = nla_nest_start(msg, DEVLINK_ATTR_LINECARD_SUPPORTED_TYPES);
> +	if (!attr)
> +		return -EMSGSIZE;
> +	for (i = 0; i < linecard->ops->supported_types_count; i++) {
> +		if (nla_put_string(msg, DEVLINK_ATTR_LINECARD_TYPE,
> +				   linecard->ops->supported_types[i]))
> +			goto nla_put_failure;
> +	}
> +	nla_nest_end(msg, attr);
>  
>  	genlmsg_end(msg, hdr);
>  	return 0;
> @@ -1300,6 +1318,68 @@ static int devlink_nl_cmd_linecard_get_dumpit(struct sk_buff *msg,
>  	return msg->len;
>  }
>  
> +static int devlink_nl_cmd_linecard_provision_doit(struct sk_buff *skb,
> +						  struct genl_info *info)
> +{
> +	struct devlink_linecard *linecard = info->user_ptr[1];
> +	const char *type;
> +	int i;
> +
> +	if (linecard->state == DEVLINK_LINECARD_STATE_PROVISIONING) {
> +		NL_SET_ERR_MSG_MOD(info->extack, "Linecard is currently being provisioned");
> +		return -EBUSY;
> +	}
> +	if (linecard->state == DEVLINK_LINECARD_STATE_UNPROVISIONING) {
> +		NL_SET_ERR_MSG_MOD(info->extack, "Linecard is currently being unprovisioned");
> +		return -EBUSY;
> +	}
> +	if (linecard->state != DEVLINK_LINECARD_STATE_UNPROVISIONED) {
> +		NL_SET_ERR_MSG_MOD(info->extack, "Linecard already provisioned");
> +		return -EBUSY;
> +	}
> +
> +	if (!info->attrs[DEVLINK_ATTR_LINECARD_TYPE]) {
> +		NL_SET_ERR_MSG_MOD(info->extack, "Provision type not provided");
> +		return -EINVAL;
> +	}
> +
> +	type = nla_data(info->attrs[DEVLINK_ATTR_LINECARD_TYPE]);
> +	for (i = 0; i < linecard->ops->supported_types_count; i++) {
> +		if (!strcmp(linecard->ops->supported_types[i], type)) {
> +			linecard->state = DEVLINK_LINECARD_STATE_PROVISIONING;
> +			devlink_linecard_notify(linecard, DEVLINK_CMD_LINECARD_NEW);
> +			return linecard->ops->provision(linecard,
> +							linecard->priv, i,
> +							info->extack);

So if this fails user space will see 'provisioning' although nothing is
being provisioned... Better to set the state and notify if this call did
not fail

> +		}
> +	}
> +	NL_SET_ERR_MSG_MOD(info->extack, "Unsupported provision type provided");
> +	return -EINVAL;
> +}
> +
> +static int devlink_nl_cmd_linecard_unprovision_doit(struct sk_buff *skb,
> +						    struct genl_info *info)
> +{
> +	struct devlink_linecard *linecard = info->user_ptr[1];
> +
> +	if (linecard->state == DEVLINK_LINECARD_STATE_PROVISIONING) {
> +		NL_SET_ERR_MSG_MOD(info->extack, "Linecard is currently being provisioned");
> +		return -EBUSY;
> +	}
> +	if (linecard->state == DEVLINK_LINECARD_STATE_UNPROVISIONING) {
> +		NL_SET_ERR_MSG_MOD(info->extack, "Linecard is currently being unprovisioned");
> +		return -EBUSY;
> +	}
> +	if (linecard->state == DEVLINK_LINECARD_STATE_UNPROVISIONED) {
> +		NL_SET_ERR_MSG_MOD(info->extack, "Linecard is not provisioned");
> +		return -EOPNOTSUPP;
> +	}
> +	linecard->state = DEVLINK_LINECARD_STATE_UNPROVISIONING;
> +	devlink_linecard_notify(linecard, DEVLINK_CMD_LINECARD_NEW);
> +	return linecard->ops->unprovision(linecard, linecard->priv,
> +					  info->extack);
> +}
> +
>  static int devlink_nl_sb_fill(struct sk_buff *msg, struct devlink *devlink,
>  			      struct devlink_sb *devlink_sb,
>  			      enum devlink_command cmd, u32 portid,
> @@ -7759,6 +7839,7 @@ static const struct nla_policy devlink_nl_policy[DEVLINK_ATTR_MAX + 1] = {
>  							DEVLINK_RELOAD_ACTION_MAX),
>  	[DEVLINK_ATTR_RELOAD_LIMITS] = NLA_POLICY_BITFIELD32(DEVLINK_RELOAD_LIMITS_VALID_MASK),
>  	[DEVLINK_ATTR_LINECARD_INDEX] = { .type = NLA_U32 },
> +	[DEVLINK_ATTR_LINECARD_TYPE] = { .type = NLA_NUL_STRING },
>  };
>  
>  static const struct genl_small_ops devlink_nl_ops[] = {
> @@ -7806,6 +7887,20 @@ static const struct genl_small_ops devlink_nl_ops[] = {
>  		.internal_flags = DEVLINK_NL_FLAG_NEED_LINECARD,
>  		/* can be retrieved by unprivileged users */
>  	},
> +	{
> +		.cmd = DEVLINK_CMD_LINECARD_PROVISION,
> +		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
> +		.doit = devlink_nl_cmd_linecard_provision_doit,
> +		.flags = GENL_ADMIN_PERM,
> +		.internal_flags = DEVLINK_NL_FLAG_NEED_LINECARD,
> +	},
> +	{
> +		.cmd = DEVLINK_CMD_LINECARD_UNPROVISION,
> +		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
> +		.doit = devlink_nl_cmd_linecard_unprovision_doit,
> +		.flags = GENL_ADMIN_PERM,
> +		.internal_flags = DEVLINK_NL_FLAG_NEED_LINECARD,
> +	},
>  	{
>  		.cmd = DEVLINK_CMD_SB_GET,
>  		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
> @@ -8613,11 +8708,17 @@ static int __devlink_port_phys_port_name_get(struct devlink_port *devlink_port,
>   *	Create devlink linecard instance with provided linecard index.
>   *	Caller can use any indexing, even hw-related one.
>   */
> -struct devlink_linecard *devlink_linecard_create(struct devlink *devlink,
> -						 unsigned int linecard_index)
> +struct devlink_linecard *
> +devlink_linecard_create(struct devlink *devlink, unsigned int linecard_index,
> +			const struct devlink_linecard_ops *ops, void *priv)
>  {
>  	struct devlink_linecard *linecard;
>  
> +	if (WARN_ON(!ops || !ops->supported_types ||
> +		    !ops->supported_types_count ||
> +		    !ops->provision || !ops->unprovision))
> +		return ERR_PTR(-EINVAL);
> +
>  	mutex_lock(&devlink->lock);
>  	if (devlink_linecard_index_exists(devlink, linecard_index)) {
>  		mutex_unlock(&devlink->lock);
> @@ -8630,6 +8731,9 @@ struct devlink_linecard *devlink_linecard_create(struct devlink *devlink,
>  
>  	linecard->devlink = devlink;
>  	linecard->index = linecard_index;
> +	linecard->ops = ops;
> +	linecard->priv = priv;
> +	linecard->state = DEVLINK_LINECARD_STATE_UNPROVISIONED;
>  	list_add_tail(&linecard->list, &devlink->linecard_list);
>  	mutex_unlock(&devlink->lock);
>  	devlink_linecard_notify(linecard, DEVLINK_CMD_LINECARD_NEW);
> @@ -8653,6 +8757,39 @@ void devlink_linecard_destroy(struct devlink_linecard *linecard)
>  }
>  EXPORT_SYMBOL_GPL(devlink_linecard_create);
>  
> +/**
> + *	devlink_linecard_provision_set - Set provisioning on linecard

'Set linecard as provisioned' maybe?

> + *
> + *	@devlink_linecard: devlink linecard
> + *	@type_index: index of the linecard type (in array of types in ops)
> + */
> +void devlink_linecard_provision_set(struct devlink_linecard *linecard,
> +				    u32 type_index)
> +{
> +	WARN_ON(type_index >= linecard->ops->supported_types_count);

Wouldn't this explode below when you use the index to access the array?
Maybe better to just warn and return

> +	mutex_lock(&linecard->devlink->lock);
> +	linecard->state = DEVLINK_LINECARD_STATE_PROVISIONED;
> +	linecard->provisioned_type = linecard->ops->supported_types[type_index];
> +	mutex_unlock(&linecard->devlink->lock);
> +	devlink_linecard_notify(linecard, DEVLINK_CMD_LINECARD_NEW);
> +}
> +EXPORT_SYMBOL_GPL(devlink_linecard_provision_set);
> +
> +/**
> + *	devlink_linecard_provision_clear - Clear provisioning on linecard

'Set linecard as unprovisioned' maybe?

> + *
> + *	@devlink_linecard: devlink linecard
> + */
> +void devlink_linecard_provision_clear(struct devlink_linecard *linecard)
> +{
> +	mutex_lock(&linecard->devlink->lock);
> +	linecard->state = DEVLINK_LINECARD_STATE_UNPROVISIONED;
> +	linecard->provisioned_type = NULL;
> +	mutex_unlock(&linecard->devlink->lock);
> +	devlink_linecard_notify(linecard, DEVLINK_CMD_LINECARD_NEW);
> +}
> +EXPORT_SYMBOL_GPL(devlink_linecard_provision_clear);
> +
>  int devlink_sb_register(struct devlink *devlink, unsigned int sb_index,
>  			u32 size, u16 ingress_pools_count,
>  			u16 egress_pools_count, u16 ingress_tc_count,
> -- 
> 2.26.2
> 

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