linux-kernel - [RFC PATCH v3 02/18] dyndbg: __init iterate over __dyndbg & __dyndbg

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Message-Id: <20210316050801.2446401-3-jim.cromie@gmail.com>
Date:   Mon, 15 Mar 2021 23:07:45 -0600
From:   Jim Cromie <jim.cromie@...il.com>
To:     jbaron@...mai.com, gregkh@...uxfoundation.org,
        linux-kernel@...r.kernel.org
Cc:     Jim Cromie <jim.cromie@...il.com>
Subject: [RFC PATCH v3 02/18] dyndbg: __init iterate over __dyndbg & __dyndbg_site in parallel

In dynamic_debug_init(), rework for-loop; add 2nd 'site' var, and
iterate over both __dyndbg* sections in parallel.  Replace uses of
iter->site with the new 'site' iter, add a BUG_ON to enforce the
invariant given by HEAD~1's DECLARE_DYNAMIC_DEBUG_METADATA base->site
initialization.

0- declare the new elf section start/stop, named in vmlinux.lds.h
   I disregarded a checkpatch warning about externs in c-files, stuck
   with current practice.

1- clean up use of 4 iterators for clarity:
   (iter, site), and ((iter, site)_mod_start) block markers.

2- iterate over __dyndbg_sites in parallel with __dyndbg
   s/iter->site/site/g;

3- add BUG_ON(iter->site != site)
   DECLARE_DYNAMIC_DEBUG_METADATA + linker insure this now.
   Maybe we can drop pointer, still get order.

4- var rename n to site_ct

Signed-off-by: Jim Cromie <jim.cromie@...il.com>
---
 lib/dynamic_debug.c | 36 +++++++++++++++++++++++-------------
 1 file changed, 23 insertions(+), 13 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 738c4ce28046..c3c35dcc6a59 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -41,6 +41,8 @@
 
 extern struct _ddebug __start___dyndbg[];
 extern struct _ddebug __stop___dyndbg[];
+extern struct _ddebug_site __start___dyndbg_sites[];
+extern struct _ddebug_site __stop___dyndbg_sites[];
 
 struct ddebug_table {
 	struct list_head link;
@@ -118,6 +120,7 @@ do {								\
 
 #define vpr_info(fmt, ...)	vnpr_info(1, fmt, ##__VA_ARGS__)
 #define v2pr_info(fmt, ...)	vnpr_info(2, fmt, ##__VA_ARGS__)
+#define v3pr_info(fmt, ...)	vnpr_info(3, fmt, ##__VA_ARGS__)
 
 static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
 {
@@ -1082,11 +1085,12 @@ static int __init dynamic_debug_init_control(void)
 
 static int __init dynamic_debug_init(void)
 {
-	struct _ddebug *iter, *iter_start;
+	struct _ddebug *iter, *iter_mod_start;
+	struct _ddebug_site *site, *site_mod_start;
 	const char *modname = NULL;
 	char *cmdline;
 	int ret = 0;
-	int n = 0, entries = 0, modct = 0;
+	int site_ct = 0, entries = 0, modct = 0;
 
 	if (&__start___dyndbg == &__stop___dyndbg) {
 		if (IS_ENABLED(CONFIG_DYNAMIC_DEBUG)) {
@@ -1097,23 +1101,29 @@ static int __init dynamic_debug_init(void)
 		ddebug_init_success = 1;
 		return 0;
 	}
-	iter = __start___dyndbg;
-	modname = iter->site->modname;
-	iter_start = iter;
-	for (; iter < __stop___dyndbg; iter++) {
+
+	iter = iter_mod_start = __start___dyndbg;
+	site = site_mod_start = __start___dyndbg_sites;
+	modname = site->modname;
+
+	for (; iter < __stop___dyndbg; iter++, site++) {
+
+		BUG_ON(site != iter->site);
 		entries++;
-		if (strcmp(modname, iter->site->modname)) {
+
+		if (strcmp(modname, site->modname)) {
 			modct++;
-			ret = ddebug_add_module(iter_start, n, modname);
+			ret = ddebug_add_module(iter_mod_start, site_ct, modname);
 			if (ret)
 				goto out_err;
-			n = 0;
-			modname = iter->site->modname;
-			iter_start = iter;
+			site_ct = 0;
+			modname = site->modname;
+			iter_mod_start = iter;
+			site_mod_start = site;
 		}
-		n++;
+		site_ct++;
 	}
-	ret = ddebug_add_module(iter_start, n, modname);
+	ret = ddebug_add_module(iter_mod_start, site_ct, modname);
 	if (ret)
 		goto out_err;
 
-- 
2.29.2