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Message-ID: <22989ed1-90a4-4acd-9ca0-00f65677ad4f@bootlin.com>
Date: Tue, 25 Feb 2025 15:08:35 +0100
From: Louis Chauvet <louis.chauvet@...tlin.com>
To: Jim Cromie <jim.cromie@...il.com>, linux-kernel@...r.kernel.org,
jbaron@...mai.com, gregkh@...uxfoundation.org, ukaszb@...omium.org
Cc: intel-gfx-trybot@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
amd-gfx@...ts.freedesktop.org, intel-gvt-dev@...ts.freedesktop.org,
intel-gfx@...ts.freedesktop.org, daniel.vetter@...ll.ch,
tvrtko.ursulin@...ux.intel.com, jani.nikula@...el.com,
ville.syrjala@...ux.intel.com
Subject: Re: [PATCH 05/63] dyndbg: replace classmap list with a vector
Le 25/01/2025 à 07:45, Jim Cromie a écrit :
> Classmaps are stored in an elf section/array, but are individually
> list-linked onto dyndbg's per-module ddebug_table for operation.
>
> This is unnecessary; even when ddebug_attach_classmap() is handling
> the builtin section (with classmaps for multiple builtin modules), its
> contents are ordered, so a module's possibly multiple classmaps will
> be consecutive in the section, and could be treated as a vector/block,
> since both start-address and subrange length are in the ddebug_info arg.
>
> IOW, this treats classmaps similarly to _ddebugs, which are already
> kept as vector-refs (address+len).
>
> So this changes:
>
> struct ddebug_class_map drops list-head link.
>
> struct ddebug_table drops the list-head maps, and gets: classes &
> num_classes for the start-address and num_classes, placed to improve
> struct packing.
>
> The loading: in ddebug_attach_module_classes(), replace the
> for-the-modname list-add loop, with a forloop that finds the module's
> subrange (start,length) of matching classmaps within the possibly
> builtin classmaps vector, and saves those to the ddebug_table.
>
> The reading/using: change list-foreach loops in ddebug_class_name() &
> ddebug_find_valid_class() to walk the array from start to length.
>
> Also:
> Move #define __outvar up, above an added use in a fn-prototype.
> Simplify ddebug_attach_module_classes args, ref has both address & len.
>
> no functional changes
>
> Signed-off-by: Jim Cromie <jim.cromie@...il.com>
> ---
> include/linux/dynamic_debug.h | 1 -
> lib/dynamic_debug.c | 61 ++++++++++++++++++-----------------
> 2 files changed, 32 insertions(+), 30 deletions(-)
>
> diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
> index b9afc7731b7c..2b0057058ecf 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 55df35df093b..41cbaa96f83d 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 {
> @@ -147,13 +148,15 @@ static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
> query->first_lineno, query->last_lineno, query->class_string);
> }
>
> +#define __outvar /* filled by callee */
Hi Jim,
What is the goal of this __outvar define? I can't find any other #define
of it in the kernel.
> 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,
> + __outvar int *class_id)
The order between __outvar and int is not important? Here you have
__outvar before int, but later [1] the __outvar is after int.
[1]:https://elixir.bootlin.com/linux/v6.14-rc3/source/lib/dynamic_debug.c#L183
Thanks,
Louis Chauvet
> {
> 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 +167,6 @@ 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
> @@ -1114,9 +1116,10 @@ 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];
>
> @@ -1200,30 +1203,31 @@ 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);
> + 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);
> + }
> }
>
> /*
> @@ -1256,10 +1260,9 @@ 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);
> @@ -1372,8 +1375,8 @@ 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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