Re: [patch net-next v4 8/9] devlink: add a command to set notification filter and use it for multicasts

Przemek Kitszel
2023-11-27T15:40:43Z

On 11/23/23 19:15, Jiri Pirko wrote:
> From: Jiri Pirko <jiri@nvidia.com>
>
> Currently the user listening on a socket for devlink notifications
> gets always all messages for all existing instances, even if he is
> interested only in one of those. That may cause unnecessary overhead
> on setups with thousands of instances present.
>
> User is currently able to narrow down the devlink objects replies
> to dump commands by specifying select attributes.
>
> Allow similar approach for notifications. Introduce a new devlink
> NOTIFY_FILTER_SET which the user passes the select attributes. Store
> these per-socket and use them for filtering messages
> during multicast send.
>
> Signed-off-by: Jiri Pirko <jiri@nvidia.com>
> ---
> v3->v4:
> - rebased on top of genl_sk_priv_*() introduction
> ---
> Documentation/netlink/specs/devlink.yaml | 10 ++++
> include/uapi/linux/devlink.h | 2 +
> net/devlink/devl_internal.h | 34 ++++++++++-
> net/devlink/netlink.c | 73 ++++++++++++++++++++++++
> net/devlink/netlink_gen.c | 15 ++++-
> net/devlink/netlink_gen.h | 4 +-
> tools/net/ynl/generated/devlink-user.c | 31 ++++++++++
> tools/net/ynl/generated/devlink-user.h | 47 +++++++++++++++
> 8 files changed, 212 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/netlink/specs/devlink.yaml b/Documentation/netlink/specs/devlink.yaml
> index 43067e1f63aa..6bad1d3454b7 100644
> --- a/Documentation/netlink/specs/devlink.yaml
> +++ b/Documentation/netlink/specs/devlink.yaml
> @@ -2055,3 +2055,13 @@ operations:
> - bus-name
> - dev-name
> - selftests
> +
> + -
> + name: notify-filter-set
> + doc: Set notification messages socket filter.
> + attribute-set: devlink
> + do:
> + request:
> + attributes:
> + - bus-name
> + - dev-name
> diff --git a/include/uapi/linux/devlink.h b/include/uapi/linux/devlink.h
> index b3c8383d342d..130cae0d3e20 100644
> --- a/include/uapi/linux/devlink.h
> +++ b/include/uapi/linux/devlink.h
> @@ -139,6 +139,8 @@ enum devlink_command {
> DEVLINK_CMD_SELFTESTS_GET, /* can dump */
> DEVLINK_CMD_SELFTESTS_RUN,
>
> + DEVLINK_CMD_NOTIFY_FILTER_SET,
> +
> /* add new commands above here */
> __DEVLINK_CMD_MAX,
> DEVLINK_CMD_MAX = __DEVLINK_CMD_MAX - 1
> diff --git a/net/devlink/devl_internal.h b/net/devlink/devl_internal.h
> index 84dc9628d3f2..82e0fb3bbebf 100644
> --- a/net/devlink/devl_internal.h
> +++ b/net/devlink/devl_internal.h
> @@ -191,11 +191,41 @@ static inline bool devlink_nl_notify_need(struct devlink *devlink)
> DEVLINK_MCGRP_CONFIG);
> }
>
> +struct devlink_obj_desc {
> + struct rcu_head rcu;
> + const char *bus_name;
> + const char *dev_name;
> + long data[];
> +};
> +
> +static inline void devlink_nl_obj_desc_init(struct devlink_obj_desc *desc,
> + struct devlink *devlink)
> +{
> + memset(desc, 0, sizeof(*desc));
> + desc->bus_name = devlink->dev->bus->name;
> + desc->dev_name = dev_name(devlink->dev);
> +}
> +
> +int devlink_nl_notify_filter(struct sock *dsk, struct sk_buff *skb, void *data);
> +
> +static inline void devlink_nl_notify_send_desc(struct devlink *devlink,
> + struct sk_buff *msg,
> + struct devlink_obj_desc *desc)
> +{
> + genlmsg_multicast_netns_filtered(&devlink_nl_family,
> + devlink_net(devlink),
> + msg, 0, DEVLINK_MCGRP_CONFIG,
> + GFP_KERNEL,
> + devlink_nl_notify_filter, desc);
> +}
> +
> static inline void devlink_nl_notify_send(struct devlink *devlink,
> struct sk_buff *msg)
> {
> - genlmsg_multicast_netns(&devlink_nl_family, devlink_net(devlink),
> - msg, 0, DEVLINK_MCGRP_CONFIG, GFP_KERNEL);
> + struct devlink_obj_desc desc;
> +
> + devlink_nl_obj_desc_init(&desc, devlink);
> + devlink_nl_notify_send_desc(devlink, msg, &desc);
> }
>
> /* Notify */
> diff --git a/net/devlink/netlink.c b/net/devlink/netlink.c
> index fa9afe3e6d9b..33a8e51dea68 100644
> --- a/net/devlink/netlink.c
> +++ b/net/devlink/netlink.c
> @@ -17,6 +17,79 @@ static const struct genl_multicast_group devlink_nl_mcgrps[] = {
> [DEVLINK_MCGRP_CONFIG] = { .name = DEVLINK_GENL_MCGRP_CONFIG_NAME },
> };
>
> +int devlink_nl_notify_filter_set_doit(struct sk_buff *skb,
> + struct genl_info *info)
> +{
> + struct nlattr **attrs = info->attrs;
> + struct devlink_obj_desc *flt;
> + size_t data_offset = 0;
> + size_t data_size = 0;
> + char *pos;
> +
> + if (attrs[DEVLINK_ATTR_BUS_NAME])
> + data_size += nla_len(attrs[DEVLINK_ATTR_BUS_NAME]) + 1;
> + if (attrs[DEVLINK_ATTR_DEV_NAME])
> + data_size += nla_len(attrs[DEVLINK_ATTR_DEV_NAME]) + 1;
> +
> + flt = kzalloc(sizeof(*flt) + data_size, GFP_KERNEL);

instead of arithmetic here, you could use struct_size()

> + if (!flt)
> + return -ENOMEM;
> +
> + pos = (char *) flt->data;
> + if (attrs[DEVLINK_ATTR_BUS_NAME]) {
> + data_offset += nla_strscpy(pos,
> + attrs[DEVLINK_ATTR_BUS_NAME],
> + data_size) + 1;
> + flt->bus_name = pos;
> + pos += data_offset;
> + }
> + if (attrs[DEVLINK_ATTR_DEV_NAME]) {
> + nla_strscpy(pos, attrs[DEVLINK_ATTR_DEV_NAME],
> + data_size - data_offset);
> + flt->dev_name = pos;
> + }
> +
> + /* Don't attach empty filter. */
> + if (!flt->bus_name && !flt->dev_name) {
> + kfree(flt);
> + flt = NULL;
> + }
> +

(Thanks for pointing out to this place in the other sub-thread)

[here1] Assume that @flt is fine here.

> + flt = genl_sk_priv_store(NETLINK_CB(skb).sk, &devlink_nl_family, flt);
> + if (IS_ERR(flt))
> + return PTR_ERR(flt);

and now you got an error from genl_sk_priv_store(),
which means that you leak old flt as of [here1].
I am correct? (sorry it's kinda late :/)

> + else if (flt)
> + kfree_rcu(flt, rcu);
> +
> + return 0;
> +}
> +
> +static bool devlink_obj_desc_match(const struct devlink_obj_desc *desc,
> + const struct devlink_obj_desc *flt)
> +{
> + if (desc->bus_name && flt->bus_name &&
> + strcmp(desc->bus_name, flt->bus_name))
> + return false;
> + if (desc->dev_name && flt->dev_name &&
> + strcmp(desc->dev_name, flt->dev_name))
> + return false;
> + return true;
> +}
> +
> +int devlink_nl_notify_filter(struct sock *dsk, struct sk_buff *skb, void *data)
> +{
> + struct devlink_obj_desc *desc = data;
> + struct devlink_obj_desc *flt;
> + int ret = 0;
> +
> + rcu_read_lock();
> + flt = genl_sk_priv_get(dsk, &devlink_nl_family);
> + if (flt)
> + ret = !devlink_obj_desc_match(desc, flt);
> + rcu_read_unlock();
> + return ret;
> +}
> +
> int devlink_nl_put_nested_handle(struct sk_buff *msg, struct net *net,
> struct devlink *devlink, int attrtype)
> {
> diff --git a/net/devlink/netlink_gen.c b/net/devlink/netlink_gen.c
> index 95f9b4350ab7..1cb0e05305d2 100644
> --- a/net/devlink/netlink_gen.c
> +++ b/net/devlink/netlink_gen.c
> @@ -560,8 +560,14 @@ static const struct nla_policy devlink_selftests_run_nl_policy[DEVLINK_ATTR_SELF
> [DEVLINK_ATTR_SELFTESTS] = NLA_POLICY_NESTED(devlink_dl_selftest_id_nl_policy),
> };
>
> +/* DEVLINK_CMD_NOTIFY_FILTER_SET - do */
> +static const struct nla_policy devlink_notify_filter_set_nl_policy[DEVLINK_ATTR_DEV_NAME + 1] = {
> + [DEVLINK_ATTR_BUS_NAME] = { .type = NLA_NUL_STRING, },
> + [DEVLINK_ATTR_DEV_NAME] = { .type = NLA_NUL_STRING, },
> +};
> +
> /* Ops table for devlink */
> -const struct genl_split_ops devlink_nl_ops[73] = {
> +const struct genl_split_ops devlink_nl_ops[74] = {
> {
> .cmd = DEVLINK_CMD_GET,
> .validate = GENL_DONT_VALIDATE_STRICT,
> @@ -1233,4 +1239,11 @@ const struct genl_split_ops devlink_nl_ops[73] = {
> .maxattr = DEVLINK_ATTR_SELFTESTS,
> .flags = GENL_ADMIN_PERM | GENL_CMD_CAP_DO,
> },
> + {
> + .cmd = DEVLINK_CMD_NOTIFY_FILTER_SET,
> + .doit = devlink_nl_notify_filter_set_doit,
> + .policy = devlink_notify_filter_set_nl_policy,
> + .maxattr = DEVLINK_ATTR_DEV_NAME,
> + .flags = GENL_CMD_CAP_DO,
> + },
> };
> diff --git a/net/devlink/netlink_gen.h b/net/devlink/netlink_gen.h
> index 02f3c0bfae0e..8f2bd50ddf5e 100644
> --- a/net/devlink/netlink_gen.h
> +++ b/net/devlink/netlink_gen.h
> @@ -16,7 +16,7 @@ extern const struct nla_policy devlink_dl_port_function_nl_policy[DEVLINK_PORT_F
> extern const struct nla_policy devlink_dl_selftest_id_nl_policy[DEVLINK_ATTR_SELFTEST_ID_FLASH + 1];
>
> /* Ops table for devlink */
> -extern const struct genl_split_ops devlink_nl_ops[73];
> +extern const struct genl_split_ops devlink_nl_ops[74];
>
> int devlink_nl_pre_doit(const struct genl_split_ops *ops, struct sk_buff *skb,
> struct genl_info *info);
> @@ -142,5 +142,7 @@ int devlink_nl_selftests_get_doit(struct sk_buff *skb, struct genl_info *info);
> int devlink_nl_selftests_get_dumpit(struct sk_buff *skb,
> struct netlink_callback *cb);
> int devlink_nl_selftests_run_doit(struct sk_buff *skb, struct genl_info *info);
> +int devlink_nl_notify_filter_set_doit(struct sk_buff *skb,
> + struct genl_info *info);
>
> #endif /* _LINUX_DEVLINK_GEN_H */
> diff --git a/tools/net/ynl/generated/devlink-user.c b/tools/net/ynl/generated/devlink-user.c
> index bc5065bd99b2..cd5f70eadf5b 100644
> --- a/tools/net/ynl/generated/devlink-user.c
> +++ b/tools/net/ynl/generated/devlink-user.c
> @@ -6830,6 +6830,37 @@ int devlink_selftests_run(struct ynl_sock *ys,
> return 0;
> }
>
> +/* ============== DEVLINK_CMD_NOTIFY_FILTER_SET ============== */
> +/* DEVLINK_CMD_NOTIFY_FILTER_SET - do */
> +void
> +devlink_notify_filter_set_req_free(struct devlink_notify_filter_set_req *req)
> +{
> + free(req->bus_name);
> + free(req->dev_name);
> + free(req);
> +}
> +
> +int devlink_notify_filter_set(struct ynl_sock *ys,
> + struct devlink_notify_filter_set_req *req)
> +{
> + struct nlmsghdr *nlh;
> + int err;
> +
> + nlh = ynl_gemsg_start_req(ys, ys->family_id, DEVLINK_CMD_NOTIFY_FILTER_SET, 1);
> + ys->req_policy = &devlink_nest;
> +
> + if (req->_present.bus_name_len)
> + mnl_attr_put_strz(nlh, DEVLINK_ATTR_BUS_NAME, req->bus_name);
> + if (req->_present.dev_name_len)
> + mnl_attr_put_strz(nlh, DEVLINK_ATTR_DEV_NAME, req->dev_name);
> +
> + err = ynl_exec(ys, nlh, NULL);
> + if (err < 0)
> + return -1;
> +
> + return 0;
> +}
> +
> const struct ynl_family ynl_devlink_family = {
> .name = "devlink",
> };
> diff --git a/tools/net/ynl/generated/devlink-user.h b/tools/net/ynl/generated/devlink-user.h
> index 1db4edc36eaa..e5d79b824a67 100644
> --- a/tools/net/ynl/generated/devlink-user.h
> +++ b/tools/net/ynl/generated/devlink-user.h
> @@ -5252,4 +5252,51 @@ devlink_selftests_run_req_set_selftests_flash(struct devlink_selftests_run_req *
> int devlink_selftests_run(struct ynl_sock *ys,
> struct devlink_selftests_run_req *req);
>
> +/* ============== DEVLINK_CMD_NOTIFY_FILTER_SET ============== */
> +/* DEVLINK_CMD_NOTIFY_FILTER_SET - do */
> +struct devlink_notify_filter_set_req {
> + struct {
> + __u32 bus_name_len;
> + __u32 dev_name_len;
> + } _present;
> +
> + char *bus_name;
> + char *dev_name;
> +};
> +
> +static inline struct devlink_notify_filter_set_req *
> +devlink_notify_filter_set_req_alloc(void)
> +{
> + return calloc(1, sizeof(struct devlink_notify_filter_set_req));
> +}
> +void
> +devlink_notify_filter_set_req_free(struct devlink_notify_filter_set_req *req);
> +
> +static inline void
> +devlink_notify_filter_set_req_set_bus_name(struct devlink_notify_filter_set_req *req,
> + const char *bus_name)
> +{
> + free(req->bus_name);
> + req->_present.bus_name_len = strlen(bus_name);
> + req->bus_name = malloc(req->_present.bus_name_len + 1);
> + memcpy(req->bus_name, bus_name, req->_present.bus_name_len);
> + req->bus_name[req->_present.bus_name_len] = 0;
> +}
> +static inline void
> +devlink_notify_filter_set_req_set_dev_name(struct devlink_notify_filter_set_req *req,
> + const char *dev_name)
> +{
> + free(req->dev_name);
> + req->_present.dev_name_len = strlen(dev_name);
> + req->dev_name = malloc(req->_present.dev_name_len + 1);
> + memcpy(req->dev_name, dev_name, req->_present.dev_name_len);
> + req->dev_name[req->_present.dev_name_len] = 0;
> +}
> +
> +/*
> + * Set notification messages socket filter.
> + */
> +int devlink_notify_filter_set(struct ynl_sock *ys,
> + struct devlink_notify_filter_set_req *req);
> +
> #endif /* _LINUX_DEVLINK_GEN_H */