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Date:   Wed, 23 Sep 2020 11:36:48 -0700
From:   Jakub Kicinski <kuba@kernel.org>
To:     Moshe Shemesh <moshe@mellanox.com>
Cc:     "David S. Miller" <davem@davemloft.net>,
        Jiri Pirko <jiri@mellanox.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next RFC v5 02/15] devlink: Add reload action limit
 level
Message-ID: <20200923113648.7398276d@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
In-Reply-To: <1600445211-31078-3-git-send-email-moshe@mellanox.com>
References: <1600445211-31078-1-git-send-email-moshe@mellanox.com>
        <1600445211-31078-3-git-send-email-moshe@mellanox.com>
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On Fri, 18 Sep 2020 19:06:38 +0300 Moshe Shemesh wrote:
> Add reload action limit level to demand restrictions on actions.
> Reload action limit levels supported:
> none (default): No constrains on actions. Driver implementation may
>                 include reset or downtime as needed to perform the
>                 actions.
> no_reset: No reset allowed, no down time allowed, no link flap and no
>           configuration is lost.
> 
> Some combinations of action and limit level are invalid. For example,
> driver can not reinitialize its entities without any downtime.
> 
> The no_reset limit level will have usecase in this patchset to
> implement restricted fw_activate on mlx5.
> 
> Signed-off-by: Moshe Shemesh <moshe@mellanox.com>
> ---
> v4 -> v5:
> - Remove check DEVLINK_RELOAD_ACTION_LIMIT_LEVEL_MAX
> - Added list of invalid action-limit_level combinations and add check to
>   supported actions and levels and check user request
> v3 -> v4:
> - New patch
> ---
>  drivers/net/ethernet/mellanox/mlx4/main.c     |  3 +
>  .../net/ethernet/mellanox/mlx5/core/devlink.c |  3 +
>  drivers/net/ethernet/mellanox/mlxsw/core.c    |  3 +
>  drivers/net/netdevsim/dev.c                   |  6 +-
>  include/net/devlink.h                         |  6 +-
>  include/uapi/linux/devlink.h                  | 17 +++++
>  net/core/devlink.c                            | 76 +++++++++++++++++--
>  7 files changed, 107 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx4/main.c b/drivers/net/ethernet/mellanox/mlx4/main.c
> index 1a482120cc0a..f0ef295af477 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/main.c
> +++ b/drivers/net/ethernet/mellanox/mlx4/main.c
> @@ -3947,6 +3947,7 @@ static int mlx4_restart_one_up(struct pci_dev *pdev, bool reload,
>  
>  static int mlx4_devlink_reload_down(struct devlink *devlink, bool netns_change,
>  				    enum devlink_reload_action action,
> +				    enum devlink_reload_action_limit_level limit_level,
>  				    struct netlink_ext_ack *extack)
>  {
>  	struct mlx4_priv *priv = devlink_priv(devlink);
> @@ -3964,6 +3965,7 @@ static int mlx4_devlink_reload_down(struct devlink *devlink, bool netns_change,
>  }
>  
>  static int mlx4_devlink_reload_up(struct devlink *devlink, enum devlink_reload_action action,
> +				  enum devlink_reload_action_limit_level limit_level,
>  				  struct netlink_ext_ack *extack, unsigned long *actions_performed)
>  {
>  	struct mlx4_priv *priv = devlink_priv(devlink);
> @@ -3985,6 +3987,7 @@ static int mlx4_devlink_reload_up(struct devlink *devlink, enum devlink_reload_a
>  static const struct devlink_ops mlx4_devlink_ops = {
>  	.port_type_set	= mlx4_devlink_port_type_set,
>  	.supported_reload_actions = BIT(DEVLINK_RELOAD_ACTION_DRIVER_REINIT),
> +	.supported_reload_action_limit_levels = BIT(DEVLINK_RELOAD_ACTION_LIMIT_LEVEL_NONE),

Please cut down the name lenghts, this is just lazy.

'supported_reload_limits' or 'cap_reload_limits' is perfectly
sufficient.

'reload_limits' would be even better. Cause what else would it be if
not a capability.

Besides I don't think drivers should have to fill negative attributes
(that they don't support something). Everyone is always going to
support NONE, since it's "unspecified" / "pick your favorite", right?

>  	.reload_down	= mlx4_devlink_reload_down,
>  	.reload_up	= mlx4_devlink_reload_up,
>  };

> diff --git a/include/uapi/linux/devlink.h b/include/uapi/linux/devlink.h
> index fdba7ab58a79..0c5d942dcbd5 100644
> --- a/include/uapi/linux/devlink.h
> +++ b/include/uapi/linux/devlink.h
> @@ -289,6 +289,22 @@ enum devlink_reload_action {
>  	DEVLINK_RELOAD_ACTION_MAX = __DEVLINK_RELOAD_ACTION_MAX - 1
>  };
>  
> +/**
> + * enum devlink_reload_action_limit_level - Reload action limit level.
> + * @DEVLINK_RELOAD_ACTION_LIMIT_LEVEL_NONE: No constrains on action. Action may include
> + *                                          reset or downtime as needed.
> + * @DEVLINK_RELOAD_ACTION_LIMIT_LEVEL_NO_RESET: No reset allowed, no down time allowed,
> + *                                              no link flap and no configuration is lost.
> + */
> +enum devlink_reload_action_limit_level {

You reserved UNSPEC for actions but not for limit level?

> +	DEVLINK_RELOAD_ACTION_LIMIT_LEVEL_NONE,
> +	DEVLINK_RELOAD_ACTION_LIMIT_LEVEL_NO_RESET,
> +
> +	/* Add new reload actions limit level above */
> +	__DEVLINK_RELOAD_ACTION_LIMIT_LEVEL_MAX,
> +	DEVLINK_RELOAD_ACTION_LIMIT_LEVEL_MAX = __DEVLINK_RELOAD_ACTION_LIMIT_LEVEL_MAX - 1
> +};
> +
>  enum devlink_attr {
>  	/* don't change the order or add anything between, this is ABI! */
>  	DEVLINK_ATTR_UNSPEC,
> @@ -480,6 +496,7 @@ enum devlink_attr {
>  
>  	DEVLINK_ATTR_RELOAD_ACTION,		/* u8 */
>  	DEVLINK_ATTR_RELOAD_ACTIONS_PERFORMED,	/* nested */
> +	DEVLINK_ATTR_RELOAD_ACTION_LIMIT_LEVEL,	/* u8 */
>  
>  	/* add new attributes above here, update the policy in devlink.c */
>  
> diff --git a/net/core/devlink.c b/net/core/devlink.c
> index 318ef29f81f2..fee6fcc7dead 100644
> --- a/net/core/devlink.c
> +++ b/net/core/devlink.c
> @@ -462,12 +462,45 @@ static int devlink_nl_put_handle(struct sk_buff *msg, struct devlink *devlink)
>  	return 0;
>  }
>  
> +struct devlink_reload_combination {
> +	enum devlink_reload_action action;
> +	enum devlink_reload_action_limit_level limit_level;
> +};
> +
> +static const struct devlink_reload_combination devlink_reload_invalid_combinations[] = {
> +	{
> +		/* can't reinitialize driver with no down time */
> +		.action = DEVLINK_RELOAD_ACTION_DRIVER_REINIT,
> +		.limit_level = DEVLINK_RELOAD_ACTION_LIMIT_LEVEL_NO_RESET,
> +	},
> +};
> +
> +static bool
> +devlink_reload_combination_is_invalid(enum devlink_reload_action action,
> +				      enum devlink_reload_action_limit_level limit_level)
> +{
> +	int i;
> +
> +	for (i = 0 ; i <  ARRAY_SIZE(devlink_reload_invalid_combinations) ; i++)

Whitespace. Did you checkpatch?

> +		if (devlink_reload_invalid_combinations[i].action == action &&
> +		    devlink_reload_invalid_combinations[i].limit_level == limit_level)
> +			return true;
> +	return false;
> +}
> +
>  static bool
>  devlink_reload_action_is_supported(struct devlink *devlink, enum devlink_reload_action action)
>  {
>  	return test_bit(action, &devlink->ops->supported_reload_actions);
>  }
>  
> +static bool
> +devlink_reload_action_limit_level_is_supported(struct devlink *devlink,
> +					       enum devlink_reload_action_limit_level limit_level)
> +{
> +	return test_bit(limit_level, &devlink->ops->supported_reload_action_limit_levels);
> +}

This single-use helper just grows LoC and muddies the code IMHO.

>  static int devlink_nl_fill(struct sk_buff *msg, struct devlink *devlink,
>  			   enum devlink_command cmd, u32 portid,
>  			   u32 seq, int flags)
> @@ -2975,22 +3008,23 @@ bool devlink_is_reload_failed(const struct devlink *devlink)
>  EXPORT_SYMBOL_GPL(devlink_is_reload_failed);
>  
>  static int devlink_reload(struct devlink *devlink, struct net *dest_net,
> -			  enum devlink_reload_action action, struct netlink_ext_ack *extack,
> -			  unsigned long *actions_performed)
> +			  enum devlink_reload_action action,
> +			  enum devlink_reload_action_limit_level limit_level,
> +			  struct netlink_ext_ack *extack, unsigned long *actions_performed)
>  {
>  	int err;
>  
>  	if (!devlink->reload_enabled)
>  		return -EOPNOTSUPP;
>  
> -	err = devlink->ops->reload_down(devlink, !!dest_net, action, extack);
> +	err = devlink->ops->reload_down(devlink, !!dest_net, action, limit_level, extack);
>  	if (err)
>  		return err;
>  
>  	if (dest_net && !net_eq(dest_net, devlink_net(devlink)))
>  		devlink_reload_netns_change(devlink, dest_net);
>  
> -	err = devlink->ops->reload_up(devlink, action, extack, actions_performed);
> +	err = devlink->ops->reload_up(devlink, action, limit_level, extack, actions_performed);
>  	devlink_reload_failed_set(devlink, !!err);
>  	if (err)
>  		return err;
> @@ -3040,6 +3074,7 @@ devlink_nl_reload_actions_performed_fill(struct sk_buff *msg,
>  
>  static int devlink_nl_cmd_reload(struct sk_buff *skb, struct genl_info *info)
>  {
> +	enum devlink_reload_action_limit_level limit_level;
>  	struct devlink *devlink = info->user_ptr[0];
>  	enum devlink_reload_action action;
>  	unsigned long actions_performed;
> @@ -3077,7 +3112,21 @@ static int devlink_nl_cmd_reload(struct sk_buff *skb, struct genl_info *info)
>  		return -EOPNOTSUPP;
>  	}
>  
> -	err = devlink_reload(devlink, dest_net, action, info->extack, &actions_performed);
> +	if (info->attrs[DEVLINK_ATTR_RELOAD_ACTION_LIMIT_LEVEL])
> +		limit_level = nla_get_u8(info->attrs[DEVLINK_ATTR_RELOAD_ACTION_LIMIT_LEVEL]);
> +	else
> +		limit_level = DEVLINK_RELOAD_ACTION_LIMIT_LEVEL_NONE;
> +
> +	if (!devlink_reload_action_limit_level_is_supported(devlink, limit_level)) {
> +		NL_SET_ERR_MSG_MOD(info->extack, "Requested limit level is not supported by the driver");
> +		return -EOPNOTSUPP;
> +	}
> +	if (devlink_reload_combination_is_invalid(action, limit_level)) {
> +		NL_SET_ERR_MSG_MOD(info->extack, "Requested limit level is invalid for this action");
> +		return -EINVAL;
> +	}
> +	err = devlink_reload(devlink, dest_net, action, limit_level, info->extack,
> +			     &actions_performed);
>  
>  	if (dest_net)
>  		put_net(dest_net);
> @@ -7154,6 +7203,7 @@ static const struct nla_policy devlink_nl_policy[DEVLINK_ATTR_MAX + 1] = {
>  	[DEVLINK_ATTR_TRAP_POLICER_BURST] = { .type = NLA_U64 },
>  	[DEVLINK_ATTR_PORT_FUNCTION] = { .type = NLA_NESTED },
>  	[DEVLINK_ATTR_RELOAD_ACTION] = { .type = NLA_U8 },
> +	[DEVLINK_ATTR_RELOAD_ACTION_LIMIT_LEVEL] = { .type = NLA_U8 },

range

>  };
>  
>  static const struct genl_ops devlink_nl_ops[] = {
> @@ -7489,6 +7539,9 @@ static struct genl_family devlink_nl_family __ro_after_init = {
>  
>  static bool devlink_reload_actions_valid(const struct devlink_ops *ops)
>  {
> +	const struct devlink_reload_combination *comb;
> +	int i;
> +
>  	if (!devlink_reload_supported(ops)) {
>  		if (WARN_ON(ops->supported_reload_actions))
>  			return false;
> @@ -7498,6 +7551,18 @@ static bool devlink_reload_actions_valid(const struct devlink_ops *ops)
>  	if (WARN_ON(ops->supported_reload_actions >= BIT(__DEVLINK_RELOAD_ACTION_MAX) ||
>  		    ops->supported_reload_actions <= BIT(DEVLINK_RELOAD_ACTION_UNSPEC)))
>  		return false;
> +
> +	if (WARN_ON(!ops->supported_reload_action_limit_levels ||
> +		    ops->supported_reload_action_limit_levels >=
> +		    BIT(__DEVLINK_RELOAD_ACTION_LIMIT_LEVEL_MAX)))
> +		return false;
> +
> +	for (i = 0; i <  ARRAY_SIZE(devlink_reload_invalid_combinations); i++)  {

White space, again.

> +		comb = &devlink_reload_invalid_combinations[i];
> +		if (ops->supported_reload_actions == BIT(comb->action) &&
> +		    ops->supported_reload_action_limit_levels == BIT(comb->limit_level))
> +			return false;
> +	}
>  	return true;
>  }
>  
> @@ -9793,6 +9858,7 @@ static void __net_exit devlink_pernet_pre_exit(struct net *net)
>  				continue;
>  			err = devlink_reload(devlink, &init_net,
>  					     DEVLINK_RELOAD_ACTION_DRIVER_REINIT,
> +					     DEVLINK_RELOAD_ACTION_LIMIT_LEVEL_NONE,
>  					     NULL, &actions_performed);
>  			if (err && err != -EOPNOTSUPP)
>  				pr_warn("Failed to reload devlink instance into init_net\n");