Documentation: dyndbg: Improve cli param examples

Jim pointed out that using $module.dyndbg= is always a more flexible
choice for using dynamic debug on the command line. The $module.dyndbg
style is checked at boot and handles if $module is a builtin. If it is
actually a loadable module, it is handled again later when the module is
loaded.

If you just use dyndbg="module $module +p" dynamic debug is only enabled
when $module is a builtin.

It was recommended to illustrate wildcard usage as well.

Suggested-by: Jim Cromie <jim.cromie@gmail.com>
Signed-off-by: Andrew Halaney <ahalaney@redhat.com>
Signed-off-by: Jason Baron <jbaron@akamai.com>
Link: https://lore.kernel.org/r/1634139622-20667-4-git-send-email-jbaron@akamai.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/Documentation/admin-guide/dynamic-debug-howto.rst b/Documentation/admin-guide/dynamic-debug-howto.rst
index d0911e7..ae264aa 100644 (file)
--- a/Documentation/admin-guide/dynamic-debug-howto.rst
+++ b/Documentation/admin-guide/dynamic-debug-howto.rst
@@ -357,7 +357,10 @@ Examples
   Kernel command line: ...
     // see whats going on in dyndbg=value processing
     dynamic_debug.verbose=1
-    // enable pr_debugs in 2 builtins, #cmt is stripped
-    dyndbg="module params +p #cmt ; module sys +p"
+    // enable pr_debugs in the btrfs module (can be builtin or loadable)
+    btrfs.dyndbg="+p"
+    // enable pr_debugs in all files under init/
+    // and the function parse_one, #cmt is stripped
+    dyndbg="file init/* +p #cmt ; func parse_one +p"
     // enable pr_debugs in 2 functions in a module loaded later
     pc87360.dyndbg="func pc87360_init_device +p; func pc87360_find +p"