[v2,02/20] test-dyndbg: show that DEBUG enables prdbgs at compiletime

Commit Message

Jim Cromie Jan. 13, 2023, 7:29 p.m. UTC

Dyndbg is required to enable prdbgs at compile-time if DEBUG is
defined.  Show this works; add the defn to test_dynamic_debug.c,
and manually inspect/verify its effect at module load:

[   15.292810] dyndbg: module:test_dynamic_debug attached 4 classes
[   15.293189] dyndbg:  32 debug prints in module test_dynamic_debug
[   15.293715] test_dd: init start
[   15.293716] test_dd: doing categories
[   15.293716] test_dd: LOW msg
...
[   15.293733] test_dd: L6 msg
[   15.293733] test_dd: L7 msg
[   15.293733] test_dd: init done

NOTES:

As is observable above, define DEBUG enables all prdbgs, including
those in mod_init-fn, and more notably, the class'd ones (callsites
with non-default class_ids).

This differs from the >control interface, which in order to properly
protect a client's class'd prdbgs, requires a "class FOO" in queries
to change them.  If this sounds wrong, note that the DEBUG is in the
module source file, and is thus privileged.

This yields an occaisional surprise; the following disables all the
compile-time enabled plain prdbgs, but leaves the class'd ones
enabled.

 :#> modprobe test_dynamic_debug dyndbg==_

Signed-off-by: Jim Cromie <[e-mail]>
---
 lib/test_dynamic_debug.c | 2 ++
 1 file changed, 2 insertions(+)

Patch

diff --git a/lib/test_dynamic_debug.c b/lib/test_dynamic_debug.c
index a01f0193a419..89dd7f285e31 100644
--- a/lib/test_dynamic_debug.c
+++ b/lib/test_dynamic_debug.c
@@ -8,6 +8,8 @@ 
 
 #define pr_fmt(fmt) "test_dd: " fmt
 
+#define DEBUG /* enable all prdbgs (plain & class'd) at compiletime */
+
 #include <linux/module.h>
 
 /* run tests by reading or writing sysfs node: do_prints */