linux-kernel - [RFC PATCH v5 04/28] dyndbg: __init iterate over __dyndbg & __dyndbg

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Date:   Tue, 11 May 2021 12:50:33 -0600
From:   Jim Cromie <jim.cromie@...il.com>
To:     Jason Baron <jbaron@...mai.com>, linux-kernel@...r.kernel.org
Cc:     linux-mm@...ck.org, Jim Cromie <jim.cromie@...il.com>
Subject: [RFC PATCH v5 04/28] dyndbg: __init iterate over __dyndbg & __dyndbg_site in parallel

In HEAD~1, a new elf section was added, and dynamic_debug_init() got
minimal adjustments; basically s/iter/iter->site/ where needed.

Now we rework the for-loop for clarity:
. iterate over both sections in parallel (iter & site)
. demote iter->site indirection (1st step towards dropping site)
. add __(start|stop)___dyndbg_sites decls (init'd in vmlinux.lds.h)
. add/rename several iterator/mod_start variables for clarity.
. add BUG_ON(iter->site != site)
. 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 c1c2c90ed944..5a33143215a4 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)
 {
@@ -1086,11 +1089,12 @@ 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)) {
@@ -1101,23 +1105,29 @@ 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;
 
-- 
2.31.1