linux-kernel - [PATCH v4 28/39] dyndbg: don't show default trace destination "0"

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Message-ID: <20240210235009.2405808-29-ukaszb@chromium.org>
Date: Sun, 11 Feb 2024 00:49:58 +0100
From: Łukasz Bartosik <ukaszb@...omium.org>
To: Jason Baron <jbaron@...mai.com>,
	Jim Cromie <jim.cromie@...il.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Kees Cook <keescook@...omium.org>,
	Douglas Anderson <dianders@...omium.org>
Cc: Guenter Roeck <groeck@...gle.com>,
	Yaniv Tzoreff <yanivt@...gle.com>,
	Benson Leung <bleung@...gle.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Vincent Whitchurch <vincent.whitchurch@...s.com>,
	Pekka Paalanen <ppaalanen@...il.com>,
	Sean Paul <seanpaul@...omium.org>,
	Daniel Vetter <daniel@...ll.ch>,
	Simon Ser <contact@...rsion.fr>,
	John Ogness <john.ogness@...utronix.de>,
	Petr Mladek <pmladek@...e.com>,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	linux-kernel@...r.kernel.org,
	upstream@...ihalf.com
Subject: [PATCH v4 28/39] dyndbg: don't show default trace destination "0"

When a callsite's trace destination is set to "0"
(default after boot) then don't show this trace
destination in /proc/dynamic_debug/control.

Signed-off-by: Łukasz Bartosik <ukaszb@...omium.org>
---
 lib/dynamic_debug.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 7723bb7dfc46..d6d797830be4 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -188,6 +188,12 @@ char *read_colon_args(const char *str, struct flag_settings *modifiers)
 	return end ? end : str + len;
 }
 
+static bool is_colon_show_args(struct dd_ctrl *ctrl)
+{
+	/* don't show trace destination when it is set to default "0" */
+	return ctrl->trace_dst;
+}
+
 /*
  * Maximum number of characters which are being displayed when
  * printing trace instance name, longer names are truncated
@@ -223,14 +229,15 @@ static inline const char *trim_prefix(const char *path)
 }
 
 typedef const char* (*read_flag_args_f)(const char *, struct flag_settings *);
+typedef bool (*is_show_args_f)(struct dd_ctrl *);
 typedef char* (*show_flag_args_f)(struct dd_ctrl *, char *);
 
 static const struct
 {
 	unsigned flag:8;
 	char opt_char;
-	bool always_show;
 	read_flag_args_f read_args;
+	is_show_args_f is_show_args;
 	show_flag_args_f show_args;
 } opt_array[] = {
 	{ _DPRINTK_FLAGS_PRINTK, 'p' },
@@ -243,7 +250,8 @@ static const struct
 	 * future use. When both T flag and ':'are provided together then
 	 * ':' has to follow T flag in the form of 'T:'.
 	 */
-	{ _DPRINTK_FLAGS_NONE, ':', true, read_colon_args, show_colon_args },
+	{ _DPRINTK_FLAGS_NONE, ':', read_colon_args, is_colon_show_args,
+				    show_colon_args },
 	{ _DPRINTK_FLAGS_INCL_MODNAME, 'm' },
 	{ _DPRINTK_FLAGS_INCL_FUNCNAME, 'f' },
 	{ _DPRINTK_FLAGS_INCL_SOURCENAME, 's' },
@@ -258,12 +266,15 @@ struct ctrlbuf { char buf[ARRAY_SIZE(opt_array)+FLAG_COLON_ARG_LEN+1]; };
 static char *ddebug_describe_ctrl(struct dd_ctrl *ctrl, struct ctrlbuf *cb)
 {
 	show_flag_args_f show_args = NULL;
+	is_show_args_f is_show_args;
 	char *p = cb->buf;
 	int i;
 
-	for (i = 0; i < ARRAY_SIZE(opt_array); ++i)
+	for (i = 0; i < ARRAY_SIZE(opt_array); ++i) {
+		is_show_args = opt_array[i].is_show_args;
+
 		if (ctrl->flags & opt_array[i].flag ||
-		    opt_array[i].always_show) {
+		    (is_show_args && is_show_args(ctrl))) {
 			if (show_args)
 				*p++ = '.';
 			*p++ = opt_array[i].opt_char;
@@ -271,6 +282,7 @@ static char *ddebug_describe_ctrl(struct dd_ctrl *ctrl, struct ctrlbuf *cb)
 			if (show_args)
 				p = show_args(ctrl, p);
 		}
+	}
 
 	if (p == cb->buf)
 		*p++ = '_';
-- 
2.43.0.687.g38aa6559b0-goog