Commit 1bbdb81a authored by Carolina Jubran's avatar Carolina Jubran Committed by Jakub Kicinski
Browse files

devlink: Fix excessive stack usage in rate TC bandwidth parsing 



The devlink_nl_rate_tc_bw_parse function uses a large stack array for
devlink attributes, which triggers a warning about excessive stack
usage:

net/devlink/rate.c: In function 'devlink_nl_rate_tc_bw_parse':
net/devlink/rate.c:382:1: error: the frame size of 1648 bytes is larger than 1536 bytes [-Werror=frame-larger-than=]

Introduce a separate attribute set specifically for rate TC bandwidth
parsing that only contains the two attributes actually used: index
and bandwidth. This reduces the stack array from DEVLINK_ATTR_MAX
entries to just 2 entries, solving the stack usage issue.

Update devlink selftest to use the new 'index' and 'bw' attribute names
consistent with the YAML spec.

Example usage with ynl with the new spec:

    ./tools/net/ynl/cli.py --spec Documentation/netlink/specs/devlink.yaml \
      --do rate-set --json '{
      "bus-name": "pci",
      "dev-name": "0000:08:00.0",
      "port-index": 1,
      "rate-tc-bws": [
        {"index": 0, "bw": 50},
        {"index": 1, "bw": 50},
        {"index": 2, "bw": 0},
        {"index": 3, "bw": 0},
        {"index": 4, "bw": 0},
        {"index": 5, "bw": 0},
        {"index": 6, "bw": 0},
        {"index": 7, "bw": 0}
      ]
    }'

    ./tools/net/ynl/cli.py --spec Documentation/netlink/specs/devlink.yaml \
      --do rate-get --json '{
      "bus-name": "pci",
      "dev-name": "0000:08:00.0",
      "port-index": 1
    }'

    output for rate-get:
    {'bus-name': 'pci',
     'dev-name': '0000:08:00.0',
     'port-index': 1,
     'rate-tc-bws': [{'bw': 50, 'index': 0},
                     {'bw': 50, 'index': 1},
                     {'bw': 0, 'index': 2},
                     {'bw': 0, 'index': 3},
                     {'bw': 0, 'index': 4},
                     {'bw': 0, 'index': 5},
                     {'bw': 0, 'index': 6},
                     {'bw': 0, 'index': 7}],
     'rate-tx-max': 0,
     'rate-tx-priority': 0,
     'rate-tx-share': 0,
     'rate-tx-weight': 0,
     'rate-type': 'leaf'}

Fixes: 566e8f10 ("devlink: Extend devlink rate API with traffic classes bandwidth management")
Reported-by: default avatarArnd Bergmann <arnd@arndb.de>
Closes: https://lore.kernel.org/netdev/20250708160652.1810573-1-arnd@kernel.org/


Reported-by: default avatarkernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202507171943.W7DJcs6Y-lkp@intel.com/


Suggested-by: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarCarolina Jubran <cjubran@nvidia.com>
Tested-by: default avatarCarolina Jubran <cjubran@nvidia.com>
Signed-off-by: default avatarTariq Toukan <tariqt@nvidia.com>
Reviewed-by: default avatarJiri Pirko <jiri@nvidia.com>
Link: https://patch.msgid.link/1753175609-330621-1-git-send-email-tariqt@nvidia.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 56613001

Documentation/netlink/specs/devlink.yaml

+11 −15
Original line number Diff line number Diff line
@@ -853,18 +853,6 @@ attribute-sets: 
        type: nest

        multi-attr: true

        nested-attributes: dl-rate-tc-bws

      -

        name: rate-tc-index

        type: u8

        checks:

          max: rate-tc-index-max

      -

        name: rate-tc-bw

        type: u32

        doc: |

             Specifies the bandwidth share assigned to the Traffic Class.

             The bandwidth for the traffic class is determined

             in proportion to the sum of the shares of all configured classes.

  -

    name: dl-dev-stats

    subset-of: devlink
@@ -1271,12 +1259,20 @@ attribute-sets: 
        type: flag

  -

    name: dl-rate-tc-bws

    subset-of: devlink

    name-prefix: devlink-rate-tc-attr-

    attributes:

      -

        name: rate-tc-index

        name: index

        type: u8

        checks:

          max: rate-tc-index-max

      -

        name: rate-tc-bw

        name: bw

        type: u32

        doc: |

             Specifies the bandwidth share assigned to the Traffic Class.

             The bandwidth for the traffic class is determined

             in proportion to the sum of the shares of all configured classes.



operations:

  enum-model: directional

include/uapi/linux/devlink.h

+9 −2
Original line number Diff line number Diff line
@@ -635,8 +635,6 @@ enum devlink_attr { 
	DEVLINK_ATTR_REGION_DIRECT,		/* flag */



	DEVLINK_ATTR_RATE_TC_BWS,		/* nested */

	DEVLINK_ATTR_RATE_TC_INDEX,		/* u8 */

	DEVLINK_ATTR_RATE_TC_BW,		/* u32 */



	/* Add new attributes above here, update the spec in

	 * Documentation/netlink/specs/devlink.yaml and re-generate
@@ -647,6 +645,15 @@ enum devlink_attr { 
	DEVLINK_ATTR_MAX = __DEVLINK_ATTR_MAX - 1

};



enum devlink_rate_tc_attr {

	DEVLINK_RATE_TC_ATTR_UNSPEC,

	DEVLINK_RATE_TC_ATTR_INDEX,		/* u8 */

	DEVLINK_RATE_TC_ATTR_BW,		/* u32 */



	__DEVLINK_RATE_TC_ATTR_MAX,

	DEVLINK_RATE_TC_ATTR_MAX = __DEVLINK_RATE_TC_ATTR_MAX - 1

};



/* Mapping between internal resource described by the field and system

 * structure

 */

net/devlink/netlink_gen.c

+3 −3
Original line number Diff line number Diff line
@@ -45,9 +45,9 @@ const struct nla_policy devlink_dl_port_function_nl_policy[DEVLINK_PORT_FN_ATTR_ 
	[DEVLINK_PORT_FN_ATTR_CAPS] = NLA_POLICY_BITFIELD32(15),

};



const struct nla_policy devlink_dl_rate_tc_bws_nl_policy[DEVLINK_ATTR_RATE_TC_BW + 1] = {

	[DEVLINK_ATTR_RATE_TC_INDEX] = NLA_POLICY_MAX(NLA_U8, DEVLINK_RATE_TC_INDEX_MAX),

	[DEVLINK_ATTR_RATE_TC_BW] = { .type = NLA_U32, },

const struct nla_policy devlink_dl_rate_tc_bws_nl_policy[DEVLINK_RATE_TC_ATTR_BW + 1] = {

	[DEVLINK_RATE_TC_ATTR_INDEX] = NLA_POLICY_MAX(NLA_U8, DEVLINK_RATE_TC_INDEX_MAX),

	[DEVLINK_RATE_TC_ATTR_BW] = { .type = NLA_U32, },

};



const struct nla_policy devlink_dl_selftest_id_nl_policy[DEVLINK_ATTR_SELFTEST_ID_FLASH + 1] = {

net/devlink/netlink_gen.h

+1 −1
Original line number Diff line number Diff line
@@ -13,7 +13,7 @@ 


/* Common nested types */

extern const struct nla_policy devlink_dl_port_function_nl_policy[DEVLINK_PORT_FN_ATTR_CAPS + 1];

extern const struct nla_policy devlink_dl_rate_tc_bws_nl_policy[DEVLINK_ATTR_RATE_TC_BW + 1];

extern const struct nla_policy devlink_dl_rate_tc_bws_nl_policy[DEVLINK_RATE_TC_ATTR_BW + 1];

extern const struct nla_policy devlink_dl_selftest_id_nl_policy[DEVLINK_ATTR_SELFTEST_ID_FLASH + 1];



/* Ops table for devlink */

net/devlink/rate.c

+10 −10
Original line number Diff line number Diff line
@@ -90,8 +90,8 @@ static int devlink_rate_put_tc_bws(struct sk_buff *msg, u32 *tc_bw) 
		if (!nla_tc_bw)

			return -EMSGSIZE;



		if (nla_put_u8(msg, DEVLINK_ATTR_RATE_TC_INDEX, i) ||

		    nla_put_u32(msg, DEVLINK_ATTR_RATE_TC_BW, tc_bw[i]))

		if (nla_put_u8(msg, DEVLINK_RATE_TC_ATTR_INDEX, i) ||

		    nla_put_u32(msg, DEVLINK_RATE_TC_ATTR_BW, tc_bw[i]))

			goto nla_put_failure;



		nla_nest_end(msg, nla_tc_bw);
@@ -346,26 +346,26 @@ static int devlink_nl_rate_tc_bw_parse(struct nlattr *parent_nest, u32 *tc_bw, 
				       unsigned long *bitmap,

				       struct netlink_ext_ack *extack)

{

	struct nlattr *tb[DEVLINK_ATTR_MAX + 1];

	struct nlattr *tb[DEVLINK_RATE_TC_ATTR_MAX + 1];

	u8 tc_index;

	int err;



	err = nla_parse_nested(tb, DEVLINK_ATTR_MAX, parent_nest,

	err = nla_parse_nested(tb, DEVLINK_RATE_TC_ATTR_MAX, parent_nest,

			       devlink_dl_rate_tc_bws_nl_policy, extack);

	if (err)

		return err;



	if (!tb[DEVLINK_ATTR_RATE_TC_INDEX]) {

	if (!tb[DEVLINK_RATE_TC_ATTR_INDEX]) {

		NL_SET_ERR_ATTR_MISS(extack, parent_nest,

				     DEVLINK_ATTR_RATE_TC_INDEX);

				     DEVLINK_RATE_TC_ATTR_INDEX);

		return -EINVAL;

	}



	tc_index = nla_get_u8(tb[DEVLINK_ATTR_RATE_TC_INDEX]);

	tc_index = nla_get_u8(tb[DEVLINK_RATE_TC_ATTR_INDEX]);



	if (!tb[DEVLINK_ATTR_RATE_TC_BW]) {

	if (!tb[DEVLINK_RATE_TC_ATTR_BW]) {

		NL_SET_ERR_ATTR_MISS(extack, parent_nest,

				     DEVLINK_ATTR_RATE_TC_BW);

				     DEVLINK_RATE_TC_ATTR_BW);

		return -EINVAL;

	}
@@ -376,7 +376,7 @@ static int devlink_nl_rate_tc_bw_parse(struct nlattr *parent_nest, u32 *tc_bw, 
		return -EINVAL;

	}



	tc_bw[tc_index] = nla_get_u32(tb[DEVLINK_ATTR_RATE_TC_BW]);

	tc_bw[tc_index] = nla_get_u32(tb[DEVLINK_RATE_TC_ATTR_BW]);



	return 0;

}