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devlink: support default values for param-get and param-set

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Support querying and resetting to default param values.

Introduce two new devlink netlink attrs:
DEVLINK_ATTR_PARAM_VALUE_DEFAULT and
DEVLINK_ATTR_PARAM_RESET_DEFAULT. The former is used to contain an
optional parameter value inside of the param_value nested
attribute. The latter is used in param-set requests from userspace to
indicate that the driver should reset the param to its default value.

To implement this, two new functions are added to the devlink driver
api: devlink_param::get_default() and
devlink_param::reset_default(). These callbacks allow drivers to
implement default param actions for runtime and permanent cmodes. For
driverinit params, the core latches the last value set by a driver via
devl_param_driverinit_value_set(), and uses that as the default value
for a param.

Because default parameter values are optional, it would be impossible
to discern whether or not a param of type bool has default value of
false or not provided if the default value is encoded using a netlink
flag type. For this reason, when a DEVLINK_PARAM_TYPE_BOOL has an
associated default value, the default value is encoded using a u8
type.

Signed-off-by: Daniel Zahka <daniel.zahka@gmail.com>
Link: https://patch.msgid.link/20251119025038.651131-4-daniel.zahka@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Daniel Zahka
2025-11-18 18:50:33 -08:00
committed by Jakub Kicinski
parent 17a42aa465
commit 2a367002ed
6 changed files with 160 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files

9
Documentation/netlink/specs/devlink.yaml
View File

@@ -859,6 +859,14 @@ attribute-sets:
name: health-reporter-burst-period
type: u64
doc: Time (in msec) for recoveries before starting the grace period.
# TODO: fill in the attributes in between
-
name: param-reset-default
type: flag
doc: Request restoring parameter to its default value.
value: 183
-
name: dl-dev-stats
subset-of: devlink
@@ -1793,6 +1801,7 @@ operations:
- param-type
# param-value-data is missing here as the type is variable
- param-value-cmode
- param-reset-default
-
name: region-get

10
Documentation/networking/devlink/devlink-params.rst
View File

@@ -41,6 +41,16 @@ In order for ``driverinit`` parameters to take effect, the driver must
support reloading via the ``devlink-reload`` command. This command will
request a reload of the device driver.
Default parameter values
=========================
Drivers may optionally export default values for parameters of cmode
``runtime`` and ``permanent``. For ``driverinit`` parameters, the last
value set by the driver will be used as the default value. Drivers can
also support resetting params with cmode ``runtime`` and ``permanent``
to their default values. Resetting ``driverinit`` params is supported
by devlink core without additional driver support needed.
.. _devlink_params_generic:
Generic configuration parameters

42
include/net/devlink.h
View File

@@ -479,6 +479,10 @@ struct devlink_flash_notify {
* @set: set parameter value, used for runtime and permanent
* configuration modes
* @validate: validate input value is applicable (within value range, etc.)
* @get_default: get parameter default value, used for runtime and permanent
* configuration modes
* @reset_default: reset parameter to default value, used for runtime and permanent
* configuration modes
*
* This struct should be used by the driver to fill the data for
* a parameter it registers.
@@ -498,6 +502,12 @@ struct devlink_param {
int (*validate)(struct devlink *devlink, u32 id,
union devlink_param_value val,
struct netlink_ext_ack *extack);
int (*get_default)(struct devlink *devlink, u32 id,
struct devlink_param_gset_ctx *ctx,
struct netlink_ext_ack *extack);
int (*reset_default)(struct devlink *devlink, u32 id,
enum devlink_param_cmode cmode,
struct netlink_ext_ack *extack);
};
struct devlink_param_item {
@@ -509,6 +519,7 @@ struct devlink_param_item {
* until reload.
*/
bool driverinit_value_new_valid;
union devlink_param_value driverinit_default;
};
enum devlink_param_generic_id {
@@ -630,6 +641,37 @@ enum devlink_param_generic_id {
.validate = _validate, \
}
#define DEVLINK_PARAM_GENERIC_WITH_DEFAULTS(_id, _cmodes, _get, _set, \
_validate, _get_default, \
_reset_default) \
{ \
.id = DEVLINK_PARAM_GENERIC_ID_##_id, \
.name = DEVLINK_PARAM_GENERIC_##_id##_NAME, \
.type = DEVLINK_PARAM_GENERIC_##_id##_TYPE, \
.generic = true, \
.supported_cmodes = _cmodes, \
.get = _get, \
.set = _set, \
.validate = _validate, \
.get_default = _get_default, \
.reset_default = _reset_default, \
}
#define DEVLINK_PARAM_DRIVER_WITH_DEFAULTS(_id, _name, _type, _cmodes, \
_get, _set, _validate, \
_get_default, _reset_default) \
{ \
.id = _id, \
.name = _name, \
.type = _type, \
.supported_cmodes = _cmodes, \
.get = _get, \
.set = _set, \
.validate = _validate, \
.get_default = _get_default, \
.reset_default = _reset_default, \
}
/* Identifier of board design */
#define DEVLINK_INFO_VERSION_GENERIC_BOARD_ID "board.id"
/* Revision of board design */

3
include/uapi/linux/devlink.h
View File

@@ -639,6 +639,9 @@ enum devlink_attr {
DEVLINK_ATTR_HEALTH_REPORTER_BURST_PERIOD, /* u64 */
DEVLINK_ATTR_PARAM_VALUE_DEFAULT, /* dynamic */
DEVLINK_ATTR_PARAM_RESET_DEFAULT, /* flag */
/* Add new attributes above here, update the spec in
* Documentation/netlink/specs/devlink.yaml and re-generate
* net/devlink/netlink_gen.c.

5
net/devlink/netlink_gen.c
View File

@@ -301,12 +301,13 @@ static const struct nla_policy devlink_param_get_dump_nl_policy[DEVLINK_ATTR_DEV
};
/* DEVLINK_CMD_PARAM_SET - do */
static const struct nla_policy devlink_param_set_nl_policy[DEVLINK_ATTR_PARAM_VALUE_CMODE + 1] = {
static const struct nla_policy devlink_param_set_nl_policy[DEVLINK_ATTR_PARAM_RESET_DEFAULT + 1] = {
[DEVLINK_ATTR_BUS_NAME] = { .type = NLA_NUL_STRING, },
[DEVLINK_ATTR_DEV_NAME] = { .type = NLA_NUL_STRING, },
[DEVLINK_ATTR_PARAM_NAME] = { .type = NLA_NUL_STRING, },
[DEVLINK_ATTR_PARAM_TYPE] = NLA_POLICY_VALIDATE_FN(NLA_U8, &devlink_attr_param_type_validate),
[DEVLINK_ATTR_PARAM_VALUE_CMODE] = NLA_POLICY_MAX(NLA_U8, 2),
[DEVLINK_ATTR_PARAM_RESET_DEFAULT] = { .type = NLA_FLAG, },
};
/* DEVLINK_CMD_REGION_GET - do */
@@ -919,7 +920,7 @@ const struct genl_split_ops devlink_nl_ops[74] = {
.doit = devlink_nl_param_set_doit,
.post_doit = devlink_nl_post_doit,
.policy = devlink_param_set_nl_policy,
.maxattr = DEVLINK_ATTR_PARAM_VALUE_CMODE,
.maxattr = DEVLINK_ATTR_PARAM_RESET_DEFAULT,
.flags = GENL_ADMIN_PERM | GENL_CMD_CAP_DO,
},
{

105
net/devlink/param.c
View File

@@ -192,9 +192,32 @@ static int devlink_param_set(struct devlink *devlink,
return param->set(devlink, param->id, ctx, extack);
}
static int devlink_param_get_default(struct devlink *devlink,
const struct devlink_param *param,
struct devlink_param_gset_ctx *ctx,
struct netlink_ext_ack *extack)
{
if (!param->get_default)
return -EOPNOTSUPP;
return param->get_default(devlink, param->id, ctx, extack);
}
static int devlink_param_reset_default(struct devlink *devlink,
const struct devlink_param *param,
enum devlink_param_cmode cmode,
struct netlink_ext_ack *extack)
{
if (!param->reset_default)
return -EOPNOTSUPP;
return param->reset_default(devlink, param->id, cmode, extack);
}
static int
devlink_nl_param_value_put(struct sk_buff *msg, enum devlink_param_type type,
int nla_type, union devlink_param_value val)
int nla_type, union devlink_param_value val,
bool flag_as_u8)
{
switch (type) {
case DEVLINK_PARAM_TYPE_U8:
@@ -218,8 +241,16 @@ devlink_nl_param_value_put(struct sk_buff *msg, enum devlink_param_type type,
return -EMSGSIZE;
break;
case DEVLINK_PARAM_TYPE_BOOL:
if (val.vbool && nla_put_flag(msg, nla_type))
return -EMSGSIZE;
/* default values of type bool are encoded with u8, so that
* false can be distinguished from not present
*/
if (flag_as_u8) {
if (nla_put_u8(msg, nla_type, val.vbool))
return -EMSGSIZE;
} else {
if (val.vbool && nla_put_flag(msg, nla_type))
return -EMSGSIZE;
}
break;
}
return 0;
@@ -229,7 +260,9 @@ static int
devlink_nl_param_value_fill_one(struct sk_buff *msg,
enum devlink_param_type type,
enum devlink_param_cmode cmode,
union devlink_param_value val)
union devlink_param_value val,
union devlink_param_value default_val,
bool has_default)
{
struct nlattr *param_value_attr;
int err = -EMSGSIZE;
@@ -243,10 +276,19 @@ devlink_nl_param_value_fill_one(struct sk_buff *msg,
goto value_nest_cancel;
err = devlink_nl_param_value_put(msg, type,
DEVLINK_ATTR_PARAM_VALUE_DATA, val);
DEVLINK_ATTR_PARAM_VALUE_DATA,
val, false);
if (err)
goto value_nest_cancel;
if (has_default) {
err = devlink_nl_param_value_put(msg, type,
DEVLINK_ATTR_PARAM_VALUE_DEFAULT,
default_val, true);
if (err)
goto value_nest_cancel;
}
nla_nest_end(msg, param_value_attr);
return 0;
@@ -262,7 +304,9 @@ static int devlink_nl_param_fill(struct sk_buff *msg, struct devlink *devlink,
u32 portid, u32 seq, int flags,
struct netlink_ext_ack *extack)
{
union devlink_param_value default_value[DEVLINK_PARAM_CMODE_MAX + 1];
union devlink_param_value param_value[DEVLINK_PARAM_CMODE_MAX + 1];
bool default_value_set[DEVLINK_PARAM_CMODE_MAX + 1] = {};
bool param_value_set[DEVLINK_PARAM_CMODE_MAX + 1] = {};
const struct devlink_param *param = param_item->param;
struct devlink_param_gset_ctx ctx;
@@ -283,12 +327,26 @@ static int devlink_nl_param_fill(struct sk_buff *msg, struct devlink *devlink,
param_value[i] = param_item->driverinit_value;
else
return -EOPNOTSUPP;
if (param_item->driverinit_value_valid) {
default_value[i] = param_item->driverinit_default;
default_value_set[i] = true;
}
} else {
ctx.cmode = i;
err = devlink_param_get(devlink, param, &ctx, extack);
if (err)
return err;
param_value[i] = ctx.val;
err = devlink_param_get_default(devlink, param, &ctx,
extack);
if (!err) {
default_value[i] = ctx.val;
default_value_set[i] = true;
} else if (err != -EOPNOTSUPP) {
return err;
}
}
param_value_set[i] = true;
}
@@ -325,7 +383,9 @@ static int devlink_nl_param_fill(struct sk_buff *msg, struct devlink *devlink,
if (!param_value_set[i])
continue;
err = devlink_nl_param_value_fill_one(msg, param->type,
i, param_value[i]);
i, param_value[i],
default_value[i],
default_value_set[i]);
if (err)
goto values_list_nest_cancel;
}
@@ -542,6 +602,7 @@ static int __devlink_nl_cmd_param_set_doit(struct devlink *devlink,
struct devlink_param_item *param_item;
const struct devlink_param *param;
union devlink_param_value value;
bool reset_default;
int err = 0;
param_item = devlink_param_get_from_info(params, info);
@@ -553,13 +614,18 @@ static int __devlink_nl_cmd_param_set_doit(struct devlink *devlink,
return err;
if (param_type != param->type)
return -EINVAL;
err = devlink_param_value_get_from_info(param, info, &value);
if (err)
return err;
if (param->validate) {
err = param->validate(devlink, param->id, value, info->extack);
reset_default = info->attrs[DEVLINK_ATTR_PARAM_RESET_DEFAULT];
if (!reset_default) {
err = devlink_param_value_get_from_info(param, info, &value);
if (err)
return err;
if (param->validate) {
err = param->validate(devlink, param->id, value,
info->extack);
if (err)
return err;
}
}
if (GENL_REQ_ATTR_CHECK(info, DEVLINK_ATTR_PARAM_VALUE_CMODE))
@@ -569,6 +635,15 @@ static int __devlink_nl_cmd_param_set_doit(struct devlink *devlink,
return -EOPNOTSUPP;
if (cmode == DEVLINK_PARAM_CMODE_DRIVERINIT) {
if (reset_default) {
if (!param_item->driverinit_value_valid) {
NL_SET_ERR_MSG(info->extack,
"Default value not available");
return -EOPNOTSUPP;
}
value = param_item->driverinit_default;
}
param_item->driverinit_value_new = value;
param_item->driverinit_value_new_valid = true;
} else {
@@ -576,7 +651,12 @@ static int __devlink_nl_cmd_param_set_doit(struct devlink *devlink,
return -EOPNOTSUPP;
ctx.val = value;
ctx.cmode = cmode;
err = devlink_param_set(devlink, param, &ctx, info->extack);
if (reset_default)
err = devlink_param_reset_default(devlink, param, cmode,
info->extack);
else
err = devlink_param_set(devlink, param, &ctx,
info->extack);
if (err)
return err;
}
@@ -824,6 +904,7 @@ void devl_param_driverinit_value_set(struct devlink *devlink, u32 param_id,
param_item->driverinit_value = init_val;
param_item->driverinit_value_valid = true;
param_item->driverinit_default = init_val;
devlink_param_notify(devlink, 0, param_item, DEVLINK_CMD_PARAM_NEW);
}