Re: [PATCH net-next RFC v5 02/15] devlink: Add reload action limit level

[Moshe Shemesh]

On 9/23/2020 9:36 PM, Jakub Kicinski wrote:
> 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@xxxxxxxxxxxx>
> > ---
> > 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.


Sounds good.

So instead of supported_reload_actions_limit_levels will have reload_limits.

Instead of supported_reload_actions will have reload_actions, OK ?

May also use reload_limit_level instead of reload_action_limit_level 
everywhere if its clear enough.

> 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?


Good point, will remove it.

> >        .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?


Yes, I used LIMIT_LEVEL_NONE = 0 as no limit needed, so I skipped UNSPEC.

Maybe should add UNSPEC and use UNSPEC as no limit needed. But UNSPEC is 
kind of invalid.


> > +     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?


Yes, checked it again now, it still pass. I think checkpatch doesn't see 
double space.

But anyway, I missed it, I will fix.

> > +             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.


It is used again in patch 4.

> >   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.
Same double space, I will fix.
> > +             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");