Subject: Re: [PATCH net-next V4 10/12] devlink: Add resource scope filtering to resource dump

From: Jakub Kicinski <[email-masked]>
Date: Thu, 2 Apr 2026 19:02:19 -0700

On Wed, 1 Apr 2026 21:49:45 +0300 Tariq Toukan wrote:
> @@ -873,6 +881,16 @@ attribute-sets:
>          doc: Unique devlink instance index.
>          checks:
>            max: u32-max
> +      -
> +        name: resource-scope-mask
> +        type: bitfield32

no need for a bitfield here, this is a simpler selector
bitfield is for cases when we need to update some persistent
state, in that case we want to indicate which bits we intend
to update:

	cfg = (cfg & ~bf.mask) | bf.val

scope is a straight attribute, there's no updating of anything.

u32 or unit would do

> +        enum: resource-scope
> +        enum-as-flags: true
> +        doc: |
> +          Bitmask selecting which resource classes to include in a
> +          resource-dump response. Bit 0 (dev) selects device-level
> +          resources; bit 1 (port) selects port-level resources.
> +          When absent all classes are returned.
>    -
>      name: dl-dev-stats
>      subset-of: devlink
> @@ -1775,7 +1793,11 @@ operations:
>              - resource-list
>        dump:
>          request:
> -          attributes: *dev-id-attrs
> +          attributes:
> +            - bus-name
> +            - dev-name
> +            - index
> +            - resource-scope-mask
>          reply: *resource-dump-reply
>  
>      -
> diff --git a/include/uapi/linux/devlink.h b/include/uapi/linux/devlink.h
> index 7de2d8cc862f..e0a0b523ce5c 100644
> --- a/include/uapi/linux/devlink.h
> +++ b/include/uapi/linux/devlink.h
> @@ -645,6 +645,7 @@ enum devlink_attr {
>  	DEVLINK_ATTR_PARAM_RESET_DEFAULT,	/* flag */
>  
>  	DEVLINK_ATTR_INDEX,			/* uint */
> +	DEVLINK_ATTR_RESOURCE_SCOPE_MASK,	/* bitfield32 */
>  
>  	/* Add new attributes above here, update the spec in
>  	 * Documentation/netlink/specs/devlink.yaml and re-generate
> @@ -704,6 +705,22 @@ enum devlink_resource_unit {
>  	DEVLINK_RESOURCE_UNIT_ENTRY,
>  };
>  
> +enum devlink_resource_scope {
> +	DEVLINK_RESOURCE_SCOPE_DEV_BIT,
> +	DEVLINK_RESOURCE_SCOPE_PORT_BIT,
> +
> +	__DEVLINK_RESOURCE_SCOPE_MAX_BIT,
> +	DEVLINK_RESOURCE_SCOPE_MAX_BIT =

do we need this? it's not an attr enum all we care about here is 
the mask, really so just a trailing value which is max real value + 1
is enough for all users?

> +		__DEVLINK_RESOURCE_SCOPE_MAX_BIT - 1
> +};
> +
> +#define DEVLINK_RESOURCE_SCOPE_DEV \
> +	_BITUL(DEVLINK_RESOURCE_SCOPE_DEV_BIT)
> +#define DEVLINK_RESOURCE_SCOPE_PORT \
> +	_BITUL(DEVLINK_RESOURCE_SCOPE_PORT_BIT)
> +#define DEVLINK_RESOURCE_SCOPE_VALID_MASK \
> +	(_BITUL(__DEVLINK_RESOURCE_SCOPE_MAX_BIT) - 1)
> +
>  enum devlink_port_fn_attr_cap {
>  	DEVLINK_PORT_FN_ATTR_CAP_ROCE_BIT,
>  	DEVLINK_PORT_FN_ATTR_CAP_MIGRATABLE_BIT,

> +static u32 devlink_resource_scope_get(struct nlattr **attrs, int *flags)
> +{
> +	struct nla_bitfield32 scope;
> +	u32 value;
> +
> +	if (!attrs || !attrs[DEVLINK_ATTR_RESOURCE_SCOPE_MASK])
> +		return DEVLINK_RESOURCE_SCOPE_VALID_MASK;
> +
> +	scope = nla_get_bitfield32(attrs[DEVLINK_ATTR_RESOURCE_SCOPE_MASK]);
> +	value = scope.value & scope.selector;
> +	if (value != DEVLINK_RESOURCE_SCOPE_VALID_MASK)
> +		*flags |= NLM_F_DUMP_FILTERED;
> +
> +	return value;
> +}
> +
>  static int
>  devlink_resource_dump_fill_one(struct sk_buff *skb, struct devlink *devlink,
>  			       struct devlink_port *devlink_port,
> @@ -400,16 +416,27 @@ devlink_nl_resource_dump_one(struct sk_buff *skb, struct devlink *devlink,
>  	struct devlink_nl_dump_state *state = devlink_dump_state(cb);
>  	struct devlink_port *devlink_port;
>  	unsigned long port_idx;
> +	u32 scope;
>  	int err;
>  
> -	if (!state->port_number) {
> +	scope = devlink_resource_scope_get(genl_info_dump(cb)->attrs, &flags);
> +	if (!scope) {
> +		NL_SET_ERR_MSG_ATTR(genl_info_dump(cb)->extack,
> +				    genl_info_dump(cb)->attrs[DEVLINK_ATTR_RESOURCE_SCOPE_MASK],

we have genl_info_dump(cb) 3 times here, let's save the pointer 
on the stack to make the lines shorter.

> +				    "empty resource scope selection");
> +		return -EINVAL;
> +	}
> +	if (!state->port_number && (scope & DEVLINK_RESOURCE_SCOPE_DEV)) {
>  		err = devlink_resource_dump_fill_one(skb, devlink, NULL,
> -						     cb, flags, &state->idx);
> +						     cb, flags,
> +						     &state->idx);
>  		if (err)
>  			return err;
>  		state->idx = 0;
>  	}
>  
> +	if (!(scope & DEVLINK_RESOURCE_SCOPE_PORT))
> +		goto out;
>  	xa_for_each_start(&devlink->ports, port_idx, devlink_port,
>  			  state->port_number ? state->port_number - 1 : 0) {
>  		err = devlink_resource_dump_fill_one(skb, devlink, devlink_port,
> @@ -420,6 +447,7 @@ devlink_nl_resource_dump_one(struct sk_buff *skb, struct devlink *devlink,
>  		}
>  		state->idx = 0;
>  	}
> +out:
>  	state->port_number = 0;
>  	return 0;
>  }