[PATCH 3/3] dyndbg: add source filename to prefix

From: Thomas Weißschuh
Date: Sun Jan 29 2023 - 21:01:40 EST


Printing the line number without the file is of limited usefulness.

Knowing the filename also makes it also easier to relate the logged
information to the controlfile.

Example:

# modprobe test_dynamic_debug
# echo 'file test_dynamic_debug.c =pfsl' > /proc/dynamic_debug/control
# echo 1 > /sys/module/test_dynamic_debug/parameters/do_prints
# dmesg | tail -2
[ 71.802212] do_cats:lib/test_dynamic_debug.c:103: test_dd: doing categories
[ 71.802227] do_levels:lib/test_dynamic_debug.c:123: test_dd: doing levels

Signed-off-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
---
Documentation/admin-guide/dynamic-debug-howto.rst | 5 +++--
include/linux/dynamic_debug.h | 4 +++-
lib/dynamic_debug.c | 4 ++++
3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/Documentation/admin-guide/dynamic-debug-howto.rst b/Documentation/admin-guide/dynamic-debug-howto.rst
index faa22f77847a..f9fa8163fba6 100644
--- a/Documentation/admin-guide/dynamic-debug-howto.rst
+++ b/Documentation/admin-guide/dynamic-debug-howto.rst
@@ -216,13 +216,14 @@ The flags are::
t Include thread ID, or <intr>
m Include module name
f Include the function name
+ s Include the source file name
l Include line number

For ``print_hex_dump_debug()`` and ``print_hex_dump_bytes()``, only
the ``p`` flag has meaning, other flags are ignored.

-Note the regexp ``^[-+=][flmpt_]+$`` matches a flags specification.
-To clear all flags at once, use ``=_`` or ``-flmpt``.
+Note the regexp ``^[-+=][fslmpt_]+$`` matches a flags specification.
+To clear all flags at once, use ``=_`` or ``-fslmpt``.


Debug messages during Boot Process
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index 41682278d2e8..0c77105d583c 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -37,10 +37,12 @@ struct _ddebug {
#define _DPRINTK_FLAGS_INCL_FUNCNAME (1<<2)
#define _DPRINTK_FLAGS_INCL_LINENO (1<<3)
#define _DPRINTK_FLAGS_INCL_TID (1<<4)
+#define _DPRINTK_FLAGS_INCL_SOURCENAME (1<<5)

#define _DPRINTK_FLAGS_INCL_ANY \
(_DPRINTK_FLAGS_INCL_MODNAME | _DPRINTK_FLAGS_INCL_FUNCNAME |\
- _DPRINTK_FLAGS_INCL_LINENO | _DPRINTK_FLAGS_INCL_TID)
+ _DPRINTK_FLAGS_INCL_LINENO | _DPRINTK_FLAGS_INCL_TID |\
+ _DPRINTK_FLAGS_INCL_SOURCENAME)

#if defined DEBUG
#define _DPRINTK_FLAGS_DEFAULT _DPRINTK_FLAGS_PRINT
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index e96ea427d8af..fa7418e35197 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -92,6 +92,7 @@ static const struct { unsigned flag:8; char opt_char; } opt_array[] = {
{ _DPRINTK_FLAGS_PRINT, 'p' },
{ _DPRINTK_FLAGS_INCL_MODNAME, 'm' },
{ _DPRINTK_FLAGS_INCL_FUNCNAME, 'f' },
+ { _DPRINTK_FLAGS_INCL_SOURCENAME, 's' },
{ _DPRINTK_FLAGS_INCL_LINENO, 'l' },
{ _DPRINTK_FLAGS_INCL_TID, 't' },
{ _DPRINTK_FLAGS_NONE, '_' },
@@ -836,6 +837,9 @@ static char *__dynamic_emit_prefix(const struct _ddebug *desc, char *buf)
if (desc->flags & _DPRINTK_FLAGS_INCL_FUNCNAME)
pos += snprintf(buf + pos, remaining(pos), "%s:",
desc->function);
+ if (desc->flags & _DPRINTK_FLAGS_INCL_SOURCENAME)
+ pos += snprintf(buf + pos, remaining(pos), "%s:",
+ trim_prefix(desc->filename));
if (desc->flags & _DPRINTK_FLAGS_INCL_LINENO)
pos += snprintf(buf + pos, remaining(pos), "%d:",
desc->lineno);

--
2.39.1