Le 02/04/2025 à 19:41, Jim Cromie a écrit :
Classmaps are stored in an elf section/array, but currently are
individually list-linked onto dyndbg's per-module ddebug_table for
operation. This is unnecessary.

Just like dyndbg's descriptors, classes are packed in compile order;
so even with many builtin modules employing multiple classmaps, each
modules' maps are packed contiguously, and can be treated as a
array-start-address & array-length.

So this drops the whole list building operation done in
ddebug_attach_module_classes(), and removes the list-head members.
The "select-by-modname" condition is reused to find the start,end of
the subrange.

NOTE: This "filter-by-modname" on classmaps should really be done in
ddebug_add_module(1); ie at least one step closer to ddebug_init(2),
which already splits up pr-debug descriptors into subranges by
modname, then calls (1) on each.  (2) knows nothing of classmaps
currently, and doesn't need to.  For now, just add comment.

Signed-off-by: Jim Cromie <jim.cro...@gmail.com>
---
v3- drop __outvar as promising magic it doesnt have
---
  include/linux/dynamic_debug.h |  1 -
  lib/dynamic_debug.c           | 62 ++++++++++++++++++-----------------
  2 files changed, 32 insertions(+), 31 deletions(-)

diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index ac199293d203..e458d4b838ac 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -83,7 +83,6 @@ enum class_map_type {
  };
struct ddebug_class_map {
-       struct list_head link;
        struct module *mod;
        const char *mod_name;   /* needed for builtins */
        const char **class_names;
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 621e04b1f28c..85b8d32742ec 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -45,10 +45,11 @@ extern struct ddebug_class_map __start___dyndbg_classes[];
  extern struct ddebug_class_map __stop___dyndbg_classes[];
struct ddebug_table {
-       struct list_head link, maps;
+       struct list_head link;
        const char *mod_name;
-       unsigned int num_ddebugs;
        struct _ddebug *ddebugs;
+       struct ddebug_class_map *classes;
+       unsigned int num_ddebugs, num_classes;
  };
struct ddebug_query {
@@ -148,12 +149,13 @@ 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 idx;
+       int i, idx;
- list_for_each_entry(map, &dt->maps, link) {
+       for (map = dt->classes, i = 0; i < dt->num_classes; i++, map++) {
                idx = match_string(map->class_names, map->length, class_string);
                if (idx >= 0) {
                        *class_id = idx + map->base;
@@ -164,7 +166,6 @@ static struct ddebug_class_map 
*ddebug_find_valid_class(struct ddebug_table cons
        return NULL;
  }
-#define __outvar /* filled by callee */
  /*
   * Search the tables for _ddebug's which match the given `query' and
   * apply the `flags' and `mask' to them.  Returns number of matching
@@ -180,7 +181,7 @@ static int ddebug_change(const struct ddebug_query *query,
        unsigned int nfound = 0;
        struct flagsbuf fbuf, nbuf;
        struct ddebug_class_map *map = NULL;
-       int __outvar valid_class;
+       int valid_class;
/* search for matching ddebugs */
        mutex_lock(&ddebug_lock);
@@ -1122,9 +1123,10 @@ static void *ddebug_proc_next(struct seq_file *m, void 
*p, loff_t *pos)
static const char *ddebug_class_name(struct ddebug_iter *iter, struct _ddebug *dp)
  {
-       struct ddebug_class_map *map;
+       struct ddebug_class_map *map = iter->table->classes;
+       int i, nc = iter->table->num_classes;
- list_for_each_entry(map, &iter->table->maps, link)
+       for (i = 0; i < nc; i++, map++)
                if (class_in_range(dp->class_id, map))
                        return map->class_names[dp->class_id - map->base];
@@ -1208,30 +1210,31 @@ static const struct proc_ops proc_fops = {
        .proc_write = ddebug_proc_write
  };
-static void ddebug_attach_module_classes(struct ddebug_table *dt,
-                                        struct ddebug_class_map *classes,
-                                        int num_classes)
+static void ddebug_attach_module_classes(struct ddebug_table *dt, struct 
_ddebug_info *di)
  {
        struct ddebug_class_map *cm;
-       int i, j, ct = 0;
+       int i, nc = 0;
- for (cm = classes, i = 0; i < num_classes; i++, cm++) {
+       /*
+        * 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 (cm = di->classes, i = 0; i < di->num_classes; i++, cm++) {
if (!strcmp(cm->mod_name, dt->mod_name)) {
-
-                       v2pr_info("class[%d]: module:%s base:%d len:%d 
ty:%d\n", i,
-                                 cm->mod_name, cm->base, cm->length, 
cm->map_type);
-
-                       for (j = 0; j < cm->length; j++)
-                               v3pr_info(" %d: %d %s\n", j + cm->base, j,
-                                         cm->class_names[j]);
-
-                       list_add(&cm->link, &dt->maps);
-                       ct++;
+                       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);

I think the log change belongs to patch 08 (reduce verbose/debug clutter).

With or without this:
Reviewed-by: Louis Chauvet <louis.chau...@bootlin.com>

+                               dt->classes = cm;
+                       }
+                       nc++;
                }
        }
-       if (ct)
-               vpr_info("module:%s attached %d classes\n", dt->mod_name, ct);
+       if (nc) {
+               dt->num_classes = nc;
+               vpr_info("module:%s attached %d classes\n", dt->mod_name, nc);
+       }
  }
/*
@@ -1263,10 +1266,9 @@ static int ddebug_add_module(struct _ddebug_info *di, 
const char *modname)
        dt->num_ddebugs = di->num_descs;
INIT_LIST_HEAD(&dt->link);
-       INIT_LIST_HEAD(&dt->maps);
if (di->classes && di->num_classes)
-               ddebug_attach_module_classes(dt, di->classes, di->num_classes);
+               ddebug_attach_module_classes(dt, di);
mutex_lock(&ddebug_lock);
        list_add_tail(&dt->link, &ddebug_tables);
@@ -1379,8 +1381,8 @@ static void ddebug_remove_all_tables(void)
        mutex_lock(&ddebug_lock);
        while (!list_empty(&ddebug_tables)) {
                struct ddebug_table *dt = list_entry(ddebug_tables.next,
-                                                     struct ddebug_table,
-                                                     link);
+                                                    struct ddebug_table,
+                                                    link);
                ddebug_table_free(dt);
        }
        mutex_unlock(&ddebug_lock);

--
Louis Chauvet, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com


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