devlink: introduce line card info get message

Allow the driver to provide per line card info get op to fill-up info,
similar to the "devlink dev info".

Example:

$ devlink lc info pci/0000:01:00.0 lc 8
pci/0000:01:00.0:
  lc 8
    versions:
        fixed:
          hw.revision 0
        running:
          ini.version 4
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/devlink/devlink-linecard.rst

@@ -14,6 +14,7 @@ system. Following operations are provided:
   * Get a list of supported line card types.
   * Provision of a slot with specific line card type.
   * Get and monitor of line card state and its change.
+  * Get information about line card versions.
 
 Line card according to the type may contain one or more gearboxes
 to mux the lanes with certain speed to multiple ports with lanes
@@ -120,3 +121,6 @@ Example usage
 
     # Set slot 8 to be unprovisioned:
     $ devlink lc set pci/0000:01:00.0 lc 8 notype
+
+    # Set info for slot 8:
+    $ devlink lc info pci/0000:01:00.0 lc 8

include/net/devlink.h

@@ -150,6 +150,8 @@ struct devlink_port_new_attrs {
 	   sfnum_valid:1;
 };
 
+struct devlink_info_req;
+
 /**
  * struct devlink_linecard_ops - Linecard operations
  * @provision: callback to provision the linecard slot with certain
@@ -168,6 +170,7 @@ struct devlink_port_new_attrs {
  *                  provisioned.
  * @types_count: callback to get number of supported types
  * @types_get: callback to get next type in list
+ * @info_get: callback to get linecard info
  */
 struct devlink_linecard_ops {
 	int (*provision)(struct devlink_linecard *linecard, void *priv,
@@ -182,6 +185,9 @@ struct devlink_linecard_ops {
 	void (*types_get)(struct devlink_linecard *linecard,
 			  void *priv, unsigned int index, const char **type,
 			  const void **type_priv);
+	int (*info_get)(struct devlink_linecard *linecard, void *priv,
+			struct devlink_info_req *req,
+			struct netlink_ext_ack *extack);
 };
 
 struct devlink_sb_pool_info {
@@ -628,7 +634,6 @@ struct devlink_flash_update_params {
 #define DEVLINK_SUPPORT_FLASH_UPDATE_OVERWRITE_MASK	BIT(1)
 
 struct devlink_region;
-struct devlink_info_req;
 
 /**
  * struct devlink_region_ops - Region operations

include/uapi/linux/devlink.h

@@ -136,6 +136,8 @@ enum devlink_command {
 	DEVLINK_CMD_LINECARD_NEW,
 	DEVLINK_CMD_LINECARD_DEL,
 
+	DEVLINK_CMD_LINECARD_INFO_GET,		/* can dump */
+
 	/* add new commands above here */
 	__DEVLINK_CMD_MAX,
 	DEVLINK_CMD_MAX = __DEVLINK_CMD_MAX - 1

net/core/devlink.c

@@ -2424,6 +2424,125 @@ static int devlink_nl_cmd_linecard_set_doit(struct sk_buff *skb,
 	return 0;
 }
 
+struct devlink_info_req {
+	struct sk_buff *msg;
+};
+
+static int
+devlink_nl_linecard_info_fill(struct sk_buff *msg, struct devlink *devlink,
+			      struct devlink_linecard *linecard,
+			      enum devlink_command cmd, u32 portid,
+			      u32 seq, int flags, struct netlink_ext_ack *extack)
+{
+	struct devlink_info_req req;
+	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 nla_put_failure;
+	if (nla_put_u32(msg, DEVLINK_ATTR_LINECARD_INDEX, linecard->index))
+		goto nla_put_failure;
+
+	req.msg = msg;
+	err = linecard->ops->info_get(linecard, linecard->priv, &req, extack);
+	if (err)
+		goto nla_put_failure;
+
+	genlmsg_end(msg, hdr);
+	return 0;
+
+nla_put_failure:
+	genlmsg_cancel(msg, hdr);
+	return err;
+}
+
+static int devlink_nl_cmd_linecard_info_get_doit(struct sk_buff *skb,
+						 struct genl_info *info)
+{
+	struct devlink_linecard *linecard = info->user_ptr[1];
+	struct devlink *devlink = linecard->devlink;
+	struct sk_buff *msg;
+	int err;
+
+	if (!linecard->ops->info_get)
+		return -EOPNOTSUPP;
+
+	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+
+	mutex_lock(&linecard->state_lock);
+	err = devlink_nl_linecard_info_fill(msg, devlink, linecard,
+					    DEVLINK_CMD_LINECARD_INFO_GET,
+					    info->snd_portid, info->snd_seq, 0,
+					    info->extack);
+	mutex_unlock(&linecard->state_lock);
+	if (err) {
+		nlmsg_free(msg);
+		return err;
+	}
+
+	return genlmsg_reply(msg, info);
+}
+
+static int devlink_nl_cmd_linecard_info_get_dumpit(struct sk_buff *msg,
+						   struct netlink_callback *cb)
+{
+	struct devlink_linecard *linecard;
+	struct devlink *devlink;
+	int start = cb->args[0];
+	unsigned long index;
+	int idx = 0;
+	int err = 0;
+
+	mutex_lock(&devlink_mutex);
+	xa_for_each_marked(&devlinks, index, devlink, DEVLINK_REGISTERED) {
+		if (!devlink_try_get(devlink))
+			continue;
+
+		if (!net_eq(devlink_net(devlink), sock_net(msg->sk)))
+			goto retry;
+
+		mutex_lock(&devlink->linecards_lock);
+		list_for_each_entry(linecard, &devlink->linecard_list, list) {
+			if (idx < start || !linecard->ops->info_get) {
+				idx++;
+				continue;
+			}
+			mutex_lock(&linecard->state_lock);
+			err = devlink_nl_linecard_info_fill(msg, devlink, linecard,
+							    DEVLINK_CMD_LINECARD_INFO_GET,
+							    NETLINK_CB(cb->skb).portid,
+							    cb->nlh->nlmsg_seq,
+							    NLM_F_MULTI,
+							    cb->extack);
+			mutex_unlock(&linecard->state_lock);
+			if (err) {
+				mutex_unlock(&devlink->linecards_lock);
+				devlink_put(devlink);
+				goto out;
+			}
+			idx++;
+		}
+		mutex_unlock(&devlink->linecards_lock);
+retry:
+		devlink_put(devlink);
+	}
+out:
+	mutex_unlock(&devlink_mutex);
+
+	if (err != -EMSGSIZE)
+		return err;
+
+	cb->args[0] = idx;
+	return msg->len;
+}
+
 static int devlink_nl_sb_fill(struct sk_buff *msg, struct devlink *devlink,
 			      struct devlink_sb *devlink_sb,
 			      enum devlink_command cmd, u32 portid,
@@ -6416,10 +6535,6 @@ static int devlink_nl_cmd_region_read_dumpit(struct sk_buff *skb,
 	return err;
 }
 
-struct devlink_info_req {
-	struct sk_buff *msg;
-};
-
 int devlink_info_driver_name_put(struct devlink_info_req *req, const char *name)
 {
 	return nla_put_string(req->msg, DEVLINK_ATTR_INFO_DRIVER_NAME, name);
@@ -9139,6 +9254,13 @@ static const struct genl_small_ops devlink_nl_ops[] = {
 		.flags = GENL_ADMIN_PERM,
 		.internal_flags = DEVLINK_NL_FLAG_NEED_LINECARD,
 	},
+	{
+		.cmd = DEVLINK_CMD_LINECARD_INFO_GET,
+		.doit = devlink_nl_cmd_linecard_info_get_doit,
+		.dumpit = devlink_nl_cmd_linecard_info_get_dumpit,
+		.internal_flags = DEVLINK_NL_FLAG_NEED_LINECARD,
+		/* can be retrieved by unprivileged users */
+	},
 	{
 		.cmd = DEVLINK_CMD_SB_GET,
 		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,