ethtool -i has served us well for a long time, but its showing
its limitations more and more.  The device information should
also be reported per device not per-netdev.

Lay foundation for a simple devlink-based ethtool -i replacement.
Add device serial number as initial piece of information exposed
via this standard API.

Signed-off-by: Jakub Kicinski <jakub.kicin...@netronome.com>
---
 include/net/devlink.h        |   2 +
 include/uapi/linux/devlink.h |   4 ++
 net/core/devlink.c           | 112 +++++++++++++++++++++++++++++++++++
 3 files changed, 118 insertions(+)

diff --git a/include/net/devlink.h b/include/net/devlink.h
index 67f4293bc970..4358c111ce83 100644
--- a/include/net/devlink.h
+++ b/include/net/devlink.h
@@ -475,6 +475,8 @@ struct devlink_ops {
        int (*eswitch_encap_mode_get)(struct devlink *devlink, u8 
*p_encap_mode);
        int (*eswitch_encap_mode_set)(struct devlink *devlink, u8 encap_mode,
                                      struct netlink_ext_ack *extack);
+       int (*serial_get)(struct devlink *devlink, u8 *buf, size_t buf_len,
+                         size_t *len, struct netlink_ext_ack *extack);
 };
 
 static inline void *devlink_priv(struct devlink *devlink)
diff --git a/include/uapi/linux/devlink.h b/include/uapi/linux/devlink.h
index 6e52d3660654..760c9c360330 100644
--- a/include/uapi/linux/devlink.h
+++ b/include/uapi/linux/devlink.h
@@ -89,6 +89,8 @@ enum devlink_command {
        DEVLINK_CMD_REGION_DEL,
        DEVLINK_CMD_REGION_READ,
 
+       DEVLINK_CMD_INFO_GET,
+
        /* add new commands above here */
        __DEVLINK_CMD_MAX,
        DEVLINK_CMD_MAX = __DEVLINK_CMD_MAX - 1
@@ -285,6 +287,8 @@ enum devlink_attr {
        DEVLINK_ATTR_REGION_CHUNK_ADDR,         /* u64 */
        DEVLINK_ATTR_REGION_CHUNK_LEN,          /* u64 */
 
+       DEVLINK_ATTR_INFO_SERIAL_NUMBER,        /* binary */
+
        /* add new attributes above here, update the policy in devlink.c */
 
        __DEVLINK_ATTR_MAX,
diff --git a/net/core/devlink.c b/net/core/devlink.c
index abb0da9d7b4b..55b7b006df28 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -3597,6 +3597,110 @@ static int devlink_nl_cmd_region_read_dumpit(struct 
sk_buff *skb,
        return 0;
 }
 
+static int devlink_nl_info_sn_fill(struct sk_buff *msg, struct devlink 
*devlink,
+                                  struct netlink_ext_ack *extack)
+{
+       unsigned char sn[32];
+       size_t len = 0;
+       int err;
+
+       if (!devlink->ops->serial_get)
+               return 0;
+
+       err = devlink->ops->serial_get(devlink, sn, ARRAY_SIZE(sn), &len,
+                                      extack);
+       if (err)
+               return err;
+
+       return nla_put(msg, DEVLINK_ATTR_INFO_SERIAL_NUMBER, len, sn);
+}
+
+static int
+devlink_nl_info_fill(struct sk_buff *msg, struct devlink *devlink,
+                    enum devlink_command cmd, u32 portid,
+                    u32 seq, int flags, struct netlink_ext_ack *extack)
+{
+       void *hdr;
+       int err;
+
+       hdr = genlmsg_put(msg, portid, seq, &devlink_nl_family, flags, cmd);
+       if (!hdr)
+               return -EMSGSIZE;
+
+       err = -EMSGSIZE;
+       if (devlink_nl_put_handle(msg, devlink))
+               goto err_cancel_msg;
+
+       err = devlink_nl_info_sn_fill(msg, devlink, extack);
+       if (err)
+               goto err_cancel_msg;
+
+       genlmsg_end(msg, hdr);
+       return 0;
+
+err_cancel_msg:
+       genlmsg_cancel(msg, hdr);
+       return err;
+}
+
+static int devlink_nl_cmd_info_get_doit(struct sk_buff *skb,
+                                       struct genl_info *info)
+{
+       struct devlink *devlink = info->user_ptr[0];
+       struct sk_buff *msg;
+       int err;
+
+       if (!devlink->ops || !devlink->ops->serial_get)
+               return -EOPNOTSUPP;
+
+       msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+       if (!msg)
+               return -ENOMEM;
+
+       err = devlink_nl_info_fill(msg, devlink, DEVLINK_CMD_INFO_GET,
+                                  info->snd_portid, info->snd_seq, 0,
+                                  info->extack);
+       if (err) {
+               nlmsg_free(msg);
+               return err;
+       }
+
+       return genlmsg_reply(msg, info);
+}
+
+static int devlink_nl_cmd_info_get_dumpit(struct sk_buff *msg,
+                                         struct netlink_callback *cb)
+{
+       struct devlink *devlink;
+       int start = cb->args[0];
+       int idx = 0;
+       int err;
+
+       mutex_lock(&devlink_mutex);
+       list_for_each_entry(devlink, &devlink_list, list) {
+               if (!net_eq(devlink_net(devlink), sock_net(msg->sk)))
+                       continue;
+               if (idx < start) {
+                       idx++;
+                       continue;
+               }
+
+               mutex_lock(&devlink->lock);
+               err = devlink_nl_info_fill(msg, devlink, DEVLINK_CMD_INFO_GET,
+                                          NETLINK_CB(cb->skb).portid,
+                                          cb->nlh->nlmsg_seq, NLM_F_MULTI,
+                                          cb->extack);
+               mutex_unlock(&devlink->lock);
+               if (err)
+                       break;
+               idx++;
+       }
+       mutex_unlock(&devlink_mutex);
+
+       cb->args[0] = idx;
+       return msg->len;
+}
+
 static const struct nla_policy devlink_nl_policy[DEVLINK_ATTR_MAX + 1] = {
        [DEVLINK_ATTR_BUS_NAME] = { .type = NLA_NUL_STRING },
        [DEVLINK_ATTR_DEV_NAME] = { .type = NLA_NUL_STRING },
@@ -3842,6 +3946,14 @@ static const struct genl_ops devlink_nl_ops[] = {
                .flags = GENL_ADMIN_PERM,
                .internal_flags = DEVLINK_NL_FLAG_NEED_DEVLINK,
        },
+       {
+               .cmd = DEVLINK_CMD_INFO_GET,
+               .doit = devlink_nl_cmd_info_get_doit,
+               .dumpit = devlink_nl_cmd_info_get_dumpit,
+               .policy = devlink_nl_policy,
+               .internal_flags = DEVLINK_NL_FLAG_NEED_DEVLINK,
+               /* can be retrieved by unprivileged users */
+       },
 };
 
 static struct genl_family devlink_nl_family __ro_after_init = {
-- 
2.19.2

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