ddb: Rework macros to make it easier to add new command tables.

- Add new DB_DEFINE_TABLE and DB_DECLARE_TABLE macros to define new
  command tables.  DB_DECLARE_TABLE is intended for use in headers
  similar to MALLOC_DECLARE and SYSCTL_DECL.

  DB_DEFINE_TABLE takes three arguments, the name of the parent table,
  the command name, and the name of the table itself, e.g.
  DB_DEFINE_TABLE(show, foo, show_foo) defines a new "show foo" table.

- DB_TABLE_COMMAND, DB_TABLE_COMMAND_FLAGS, DB_TABLE_ALIAS, and
  DB_ALIAS_FLAGS allow new commands and aliases to be defined.  These
  are similar to the existing DB_COMMAND, etc. except that they take
  an initial argument giving the name of the parent table, e.g.:

  DB_TABLE_COMMAND(show_foo, bar, db_show_foo_bar)

  defines a new "show foo bar" command.

This provides a cleaner interface than the ad-hoc use of internal
macros like _DB_SET that was required previously (e.g. in cxgbe(4)).

This retires DB_FUNC macro as well as the internal _DB_FUNC macro.

Reviewed by:	melifaro, kib, markj
Differential Revision:	https://reviews.freebsd.org/D40819

2 files changed, 43 insertions, 4 deletions

diff --git a/share/man/man9/DB_COMMAND.9 b/share/man/man9/DB_COMMAND.9
index 15c2adce3580..ebf15f8b73f3 100644
--- a/share/man/man9/DB_COMMAND.9
+++ b/share/man/man9/DB_COMMAND.9
@@ -25,7 +25,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd June 24, 2022
+.Dd July 5, 2023
 .Dt DB_COMMAND 9
 .Os
 .Sh NAME
@@ -34,11 +34,17 @@
 .Nm DB_SHOW_COMMAND ,
 .Nm DB_SHOW_COMMAND_FLAGS ,
 .Nm DB_SHOW_ALL_COMMAND ,
+.Nm DB_TABLE_COMMAND ,
+.Nm DB_TABLE_COMMAND_FLAGS ,
 .Nm DB_ALIAS ,
 .Nm DB_ALIAS_FLAGS ,
 .Nm DB_SHOW_ALIAS ,
 .Nm DB_SHOW_ALIAS_FLAGS ,
-.Nm DB_SHOW_ALL_ALIAS
+.Nm DB_SHOW_ALL_ALIAS ,
+.Nm DB_TABLE_ALIAS ,
+.Nm DB_TABLE_ALIAS_FLAGS
+.Nm DB_DECLARE_TABLE ,
+.Nm DB_DEFINE_TABLE ,
 .Nd Extends the ddb command set
 .Sh SYNOPSIS
 .In ddb/ddb.h
@@ -47,11 +53,17 @@
 .Fn DB_SHOW_COMMAND "command_name" "command_function"
 .Fn DB_SHOW_COMMAND_FLAGS "command_name" "command_function" "flags"
 .Fn DB_SHOW_ALL_COMMAND "command_name" "command_function"
+.Fn DB_TABLE_COMMAND "table" "command_name" "command_function"
+.Fn DB_TABLE_COMMAND_FLAGS "table" "command_name" "command_function" "flags"
 .Fn DB_ALIAS "alias_name" "command_function"
 .Fn DB_ALIAS_FLAGS "alias_name" "command_function" "flags"
 .Fn DB_SHOW_ALIAS "alias_name" "command_function"
 .Fn DB_SHOW_ALIAS_FLAGS "alias_name" "command_function" "flags"
 .Fn DB_SHOW_ALL_ALIAS "alias_name" "command_function"
+.Fn DB_TABLE_ALIAS "table" "alias_name" "command_function"
+.Fn DB_TABLE_ALIAS_FLAGS "table" "alias_name" "command_function" "flags"
+.Fn DB_DEFINE_TABLE "parent" "name" "table"
+.Fn DB_DECLARE_TABLE "table"
 .Sh DESCRIPTION
 The
 .Fn DB_COMMAND
@@ -78,10 +90,18 @@ command and
 command, respectively.
 .Pp
 The
+.Fn DB_TABLE_COMMAND
+macro is also similar to
+.Fn DB_COMMAND
+but adds the new command as a sub-command of the ddb command
+.Fa table .
+.Pp
+The
 .Fn DB_ALIAS ,
 .Fn DB_SHOW_ALIAS ,
+.Fn DB_SHOW_ALL_ALIAS ,
 and
-.Fn DB_SHOW_ALL_ALIAS
+.Fn DB_TABLE_ALIAS
 macros register the existing
 .Fa command_function
 under the alternative command name
@@ -117,6 +137,19 @@ For example, the
 .Sy examine
 command will display words in decimal form if it is passed the modifier "d".
 .El
+.Pp
+The
+.Fn DB_DEFINE_TABLE
+macro adds a new command
+.Fa name
+as a sub-command of the existing command table
+.Fa parent .
+The new command defines a table named
+.Fa table
+which contains sub-commands.
+New commands and aliases can be added to this table by passing
+.Fa table
+as the first argument to one of the DB_TABLE_ macros.
 .Sh EXAMPLES
 In your module, the command is declared as:
 .Bd -literal
diff --git a/share/man/man9/Makefile b/share/man/man9/Makefile
index 2a320cf0fcba..45f9ec9b0515 100644
--- a/share/man/man9/Makefile
+++ b/share/man/man9/Makefile
@@ -983,7 +983,13 @@ MLINKS+=DB_COMMAND.9 DB_ALIAS.9 \
 	DB_COMMAND.9 DB_SHOW_ALL_ALIAS.9 \
 	DB_COMMAND.9 DB_SHOW_ALL_COMMAND.9 \
 	DB_COMMAND.9 DB_SHOW_COMMAND.9 \
-	DB_COMMAND.9 DB_SHOW_COMMAND_FLAGS.9
+	DB_COMMAND.9 DB_SHOW_COMMAND_FLAGS.9 \
+	DB_COMMAND.9 DB_DECLARE_TABLE.9 \
+	DB_COMMAND.9 DB_DEFINE_TABLE.9 \
+	DB_COMMAND.9 DB_TABLE_COMMAND.9 \
+	DB_COMMAND.9 DB_TABLE_COMMAND_FLAGS.9 \
+	DB_COMMAND.9 DB_TABLE_ALIAS.9 \
+	DB_COMMAND.9 DB_TABLE_ALIAS_FLAGS.9
 MLINKS+=DECLARE_MODULE.9 DECLARE_MODULE_TIED.9
 MLINKS+=dev_clone.9 drain_dev_clone_events.9
 MLINKS+=dev_refthread.9 devvn_refthread.9 \