linux-kernel - [PATCH v6 05/57] dyndbg: reverse module.callsite walk in cat control

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Date:   Sun,  4 Sep 2022 15:40:42 -0600
From:   Jim Cromie <jim.cromie@...il.com>
To:     jbaron@...mai.com, gregkh@...uxfoundation.org,
        dri-devel@...ts.freedesktop.org, amd-gfx@...ts.freedesktop.org,
        intel-gvt-dev@...ts.freedesktop.org,
        intel-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Cc:     daniel.vetter@...ll.ch, seanpaul@...omium.org, robdclark@...il.com,
        linux@...musvillemoes.dk, joe@...ches.com,
        Jim Cromie <jim.cromie@...il.com>
Subject: [PATCH v6 05/57] dyndbg: reverse module.callsite walk in cat control

Walk the module's vector of callsites backwards; ie N..0.  This
"corrects" the backwards appearance of a module's prdbg vector when
walked 0..N.  I think this is due to linker mechanics, which I'm
inclined to treat as immutable, and the order is fixable in display.

No functional changes.

Combined with previous commit, which reversed tables-list, we get:

  :#> head -n7 /proc/dynamic_debug/control
  # filename:lineno [module]function flags format
  init/main.c:1179 [main]initcall_blacklist =_ "blacklisting initcall %s\012"
  init/main.c:1218 [main]initcall_blacklisted =_ "initcall %s blacklisted\012"
  init/main.c:1424 [main]run_init_process =_ "  with arguments:\012"
  init/main.c:1426 [main]run_init_process =_ "    %s\012"
  init/main.c:1427 [main]run_init_process =_ "  with environment:\012"
  init/main.c:1429 [main]run_init_process =_ "    %s\012"

Acked-by: Jason Baron <jbaron@...mai.com>
Signed-off-by: Jim Cromie <jim.cromie@...il.com>
---
 lib/dynamic_debug.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 7fb99492c16f..8ff11977b8bd 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -59,7 +59,7 @@ struct ddebug_query {
 
 struct ddebug_iter {
 	struct ddebug_table *table;
-	unsigned int idx;
+	int idx;
 };
 
 struct flag_settings {
@@ -805,13 +805,12 @@ static struct _ddebug *ddebug_iter_first(struct ddebug_iter *iter)
 {
 	if (list_empty(&ddebug_tables)) {
 		iter->table = NULL;
-		iter->idx = 0;
 		return NULL;
 	}
 	iter->table = list_entry(ddebug_tables.next,
 				 struct ddebug_table, link);
-	iter->idx = 0;
-	return &iter->table->ddebugs[iter->idx];
+	iter->idx = iter->table->num_ddebugs;
+	return &iter->table->ddebugs[--iter->idx];
 }
 
 /*
@@ -824,15 +823,16 @@ static struct _ddebug *ddebug_iter_next(struct ddebug_iter *iter)
 {
 	if (iter->table == NULL)
 		return NULL;
-	if (++iter->idx == iter->table->num_ddebugs) {
+	if (--iter->idx < 0) {
 		/* iterate to next table */
-		iter->idx = 0;
 		if (list_is_last(&iter->table->link, &ddebug_tables)) {
 			iter->table = NULL;
 			return NULL;
 		}
 		iter->table = list_entry(iter->table->link.next,
 					 struct ddebug_table, link);
+		iter->idx = iter->table->num_ddebugs;
+		--iter->idx;
 	}
 	return &iter->table->ddebugs[iter->idx];
 }
-- 
2.37.2