linux-kernel - [PATCH v6 16/31] dyndbg: hoist classmap-filter-by-modname up to ddebug_add

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Message-ID: <20251118201842.1447666-17-jim.cromie@gmail.com>
Date: Tue, 18 Nov 2025 13:18:26 -0700
From: Jim Cromie <jim.cromie@...il.com>
To: linux-kernel@...r.kernel.org,
	dri-devel@...ts.freedesktop.org,
	gregkh@...uxfoundation.org,
	jbaron@...mai.com
Cc: ukaszb@...omium.org,
	louis.chauvet@...tlin.com,
	Jim Cromie <jim.cromie@...il.com>
Subject: [PATCH v6 16/31] dyndbg: hoist classmap-filter-by-modname up to ddebug_add_module

The body of ddebug_attach_module_classes() is dominated by a
code-block that finds the contiguous subrange of classmaps matching on
modname, and saves it into the ddebug_table's info record.

Implement this block in a macro to accommodate different component
vectors in the "box" (as named in the for_subvec macro).  We will
reuse this macro shortly.

And hoist its invocation out of ddebug_attach_module_classes() up into
ddebug_add_module().  This moves the filtering step up closer to
dynamic_debug_init(), which already segments the builtin pr_debug
descriptors on their mod_name boundaries.

Signed-off-by: Jim Cromie <jim.cromie@...il.com>
---
Ive review checkpatch complaints:
all are lvalues, and not issues.
CHECK: Macro argument reuse '_dst' - possible side-effects?
CHECK: Macro argument reuse '_sp' - possible side-effects?
CHECK: Macro argument reuse '_vec' - possible side-effects?
---
 lib/dynamic_debug.c | 57 ++++++++++++++++++++++++++-------------------
 1 file changed, 33 insertions(+), 24 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index c9377a444fc8..49de591f036a 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -170,8 +170,8 @@ static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
 }
 
 static struct _ddebug_class_map *ddebug_find_valid_class(struct ddebug_table const *dt,
-							const char *class_string,
-							int *class_id)
+							 const char *class_string,
+							 int *class_id)
 {
 	struct _ddebug_class_map *map;
 	int i, idx;
@@ -1247,30 +1247,35 @@ static const struct proc_ops proc_fops = {
 
 static void ddebug_attach_module_classes(struct ddebug_table *dt, struct _ddebug_info *di)
 {
-	struct _ddebug_class_map *cm;
-	int i, nc = 0;
-
-	/*
-	 * Find this module's classmaps in a subrange/wholerange of
-	 * the builtin/modular classmap vector/section.  Save the start
-	 * and length of the subrange at its edges.
-	 */
-	for_subvec(i, cm, di, maps) {
-		if (!strcmp(cm->mod_name, dt->mod_name)) {
-			if (!nc) {
-				v2pr_info("start subrange, class[%d]: module:%s base:%d len:%d ty:%d\n",
-					  i, cm->mod_name, cm->base, cm->length, cm->map_type);
-				dt->info.maps.start = cm;
-			}
-			nc++;
-		}
-	}
-	if (nc) {
-		dt->info.maps.len = nc;
-		vpr_info("module:%s attached %d classes\n", dt->mod_name, nc);
-	}
+	vpr_info("module:%s attached %d classes\n", dt->mod_name, dt->info.maps.len);
 }
 
+/*
+ * Walk the @_box->@_vec member, over @_vec.start[0..len], and find
+ * the contiguous subrange of elements matching on ->mod_name.  Copy
+ * the subrange into @_dst.  This depends on vars defd by caller.
+ *
+ * @_i:   caller provided counter var, init'd by macro
+ * @_sp:  cursor into @_vec.
+ * @_box: contains member named @_vec
+ * @_vec: member-name of a type with: .start .len fields.
+ * @_dst: an array-ref: to remember the module's subrange
+ */
+#define dd_mark_vector_subrange(_i, _dst, _sp, _box, _vec) ({		\
+	typeof(_dst) __dst = (_dst);					\
+	int __nc = 0;							\
+	for_subvec(_i, _sp, _box, _vec) {				\
+		if (!strcmp((_sp)->mod_name, (_dst)->mod_name)) {	\
+			if (!__nc++)					\
+				(__dst)->info._vec.start = (_sp);	\
+		} else {						\
+			if (__nc)					\
+				break; /* end of consecutive matches */ \
+		}							\
+	}								\
+	(__dst)->info._vec.len = __nc;					\
+})
+
 /*
  * Allocate a new ddebug_table for the given module
  * and add it to the global list.
@@ -1278,6 +1283,8 @@ static void ddebug_attach_module_classes(struct ddebug_table *dt, struct _ddebug
 static int ddebug_add_module(struct _ddebug_info *di, const char *modname)
 {
 	struct ddebug_table *dt;
+	struct _ddebug_class_map *cm;
+	int i;
 
 	if (!di->descs.len)
 		return 0;
@@ -1300,6 +1307,8 @@ static int ddebug_add_module(struct _ddebug_info *di, const char *modname)
 
 	INIT_LIST_HEAD(&dt->link);
 
+	dd_mark_vector_subrange(i, dt, cm, di, maps);
+
 	if (di->maps.len)
 		ddebug_attach_module_classes(dt, di);
 
-- 
2.51.1