Re: [PATCH v2 23/59] dyndbg: move .mod_name from/to structs ddebug_table/_ddebug_info

[Louis Chauvet <louis.chauvet@bootlin.com>]

Le 20/03/2025 à 19:52, Jim Cromie a écrit :
> struct _ddebug_info already has almost all dyndbg's info for a module,
> so finish the encapsulation.  This puts the datum closer to where its
> needed, improving the chance that we can obsolete the _ddebug.modame
> field with a desc_modname(dp) accessor fn.
> 
> In static ddebug_add_module(&_ddebug_info_cursor..), force the
> cursor-model by dropping the modname arg, and setting it explicitly
> into the cursor before the 3 calls to it.
> 
> struct ddebug_table only uses .mod_name when applying >control
> changes, and it has a _ddebug_info member anyway, so it keeps access
> to the field, just with a different offset.
> 
> Signed-off-by: Jim Cromie <jim.cromie@gmail.com>

Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>

> ---
>   include/linux/dynamic_debug.h |  1 +
>   lib/dynamic_debug.c           | 41 ++++++++++++++++++-----------------
>   2 files changed, 22 insertions(+), 20 deletions(-)
> 
> diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
> index 03a83a83b621..8043966a0fd6 100644
> --- a/include/linux/dynamic_debug.h
> +++ b/include/linux/dynamic_debug.h
> @@ -198,6 +198,7 @@ struct _ddebug_class_users {
>   } __packed;
>   
>   struct _ddebug_info {
> +	const char *mod_name;
>   	struct _ddebug_descs descs;
>   	struct _ddebug_class_maps maps;
>   	struct _ddebug_class_users users;
> diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
> index 3c9fb8324ad6..cd3eec5bb81c 100644
> --- a/lib/dynamic_debug.c
> +++ b/lib/dynamic_debug.c
> @@ -49,7 +49,6 @@ extern struct _ddebug_class_user __stop___dyndbg_class_users[];
>   
>   struct ddebug_table {
>   	struct list_head link;
> -	const char *mod_name;
>   	struct _ddebug_info info;
>   };
>   
> @@ -166,7 +165,7 @@ static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
>   #define vpr_dt_info(dt_p, msg_p, ...) ({				\
>   	struct ddebug_table const *_dt = dt_p;				\
>   	v2pr_info(msg_p " module:%s nd:%d nc:%d nu:%d\n", ##__VA_ARGS__, \
> -		  _dt->mod_name, _dt->info.descs.len, _dt->info.maps.len, \
> +		  _dt->info.mod_name, _dt->info.descs.len, _dt->info.maps.len, \
>   		  _dt->info.users.len);					\
>   	})
>   
> @@ -215,7 +214,7 @@ static int ddebug_change(const struct ddebug_query *query, struct flag_settings
>   
>   		/* match against the module name */
>   		if (query->module &&
> -		    !match_wildcard(query->module, dt->mod_name))
> +		    !match_wildcard(query->module, dt->info.mod_name))
>   			continue;
>   
>   		if (query->class_string) {
> @@ -283,7 +282,7 @@ static int ddebug_change(const struct ddebug_query *query, struct flag_settings
>   #endif
>   			v4pr_info("changed %s:%d [%s]%s %s => %s\n",
>   				  trim_prefix(dp->filename), dp->lineno,
> -				  dt->mod_name, dp->function,
> +				  dt->info.mod_name, dp->function,
>   				  ddebug_describe_flags(dp->flags, &fbuf),
>   				  ddebug_describe_flags(newflags, &nbuf));
>   			dp->flags = newflags;
> @@ -1123,7 +1122,7 @@ static int ddebug_proc_show(struct seq_file *m, void *p)
>   
>   	seq_printf(m, "%s:%u [%s]%s =%s \"",
>   		   trim_prefix(dp->filename), dp->lineno,
> -		   iter->table->mod_name, dp->function,
> +		   iter->table->info.mod_name, dp->function,
>   		   ddebug_describe_flags(dp->flags, &flags));
>   	seq_escape_str(m, dp->format, ESCAPE_SPACE, "\t\r\n\"");
>   	seq_putc(m, '"');
> @@ -1283,7 +1282,7 @@ static void ddebug_apply_class_users(const struct ddebug_table *dt)
>   #define dd_mark_vector_subrange(_i, _dst, _sp, _box, _vec) ({	\
>   	int nc = 0;							\
>   	for_subvec(_i, _sp, _box, _vec) {				\
> -		if (!strcmp((_sp)->mod_name, (_dst)->mod_name)) {	\
> +		if (!strcmp((_sp)->mod_name, (_dst)->info.mod_name)) {	\
>   			if (!nc++)					\
>   				(_dst)->info._vec.start = (_sp);	\
>   		} else {						\
> @@ -1314,7 +1313,7 @@ ddebug_class_range_overlap(struct _ddebug_class_map *cm,
>    * Allocate a new ddebug_table for the given module
>    * and add it to the global list.
>    */
> -static int ddebug_add_module(struct _ddebug_info *di, const char *modname)
> +static int ddebug_add_module(struct _ddebug_info *di)
>   {
>   	struct ddebug_table *dt;
>   	struct _ddebug_class_map *cm;
> @@ -1325,20 +1324,19 @@ static int ddebug_add_module(struct _ddebug_info *di, const char *modname)
>   	if (!di->descs.len)
>   		return 0;
>   
> -	v3pr_info("add-module: %s %d sites\n", modname, di->descs.len);
> +	v3pr_info("add-module: %s %d sites\n", di->mod_name, di->descs.len);
>   
>   	dt = kzalloc(sizeof(*dt), GFP_KERNEL);
>   	if (dt == NULL) {
> -		pr_err("error adding module: %s\n", modname);
> +		pr_err("error adding module: %s\n", di->mod_name);
>   		return -ENOMEM;
>   	}
>   	/*
> -	 * For built-in modules, name lives in .rodata and is
> -	 * immortal. For loaded modules, name points at the name[]
> -	 * member of struct module, which lives at least as long as
> -	 * this struct ddebug_table.
> +	 * For built-in modules, name (as supplied in di by its
> +	 * callers) lives in .rodata and is immortal. For loaded
> +	 * modules, name points at the name[] member of struct module,
> +	 * which lives at least as long as this struct ddebug_table.
>   	 */
> -	dt->mod_name = modname;
>   	dt->info = *di;
>   
>   	INIT_LIST_HEAD(&dt->link);
> @@ -1368,10 +1366,10 @@ static int ddebug_add_module(struct _ddebug_info *di, const char *modname)
>   	if (dt->info.users.len)
>   		ddebug_apply_class_users(dt);
>   
> -	vpr_info("%3u debug prints in module %s\n", di->descs.len, modname);
> +	vpr_info("%3u debug prints in module %s\n", di->descs.len, di->mod_name);
>   	return 0;
>   cleanup:
> -	WARN_ONCE("dyndbg multi-classmap conflict in %s\n", modname);
> +	WARN_ONCE("dyndbg multi-classmap conflict in %s\n", di->mod_name);
>   	kfree(dt);
>   	return -EINVAL;
>   
> @@ -1436,7 +1434,7 @@ static int ddebug_remove_module(const char *mod_name)
>   
>   	mutex_lock(&ddebug_lock);
>   	list_for_each_entry_safe(dt, nextdt, &ddebug_tables, link) {
> -		if (dt->mod_name == mod_name) {
> +		if (dt->info.mod_name == mod_name) {
>   			ddebug_table_free(dt);
>   			ret = 0;
>   			break;
> @@ -1456,7 +1454,8 @@ static int ddebug_module_notify(struct notifier_block *self, unsigned long val,
>   
>   	switch (val) {
>   	case MODULE_STATE_COMING:
> -		ret = ddebug_add_module(&mod->dyndbg_info, mod->name);
> +		mod->dyndbg_info.mod_name = mod->name;
> +		ret = ddebug_add_module(&mod->dyndbg_info);
>   		if (ret)
>   			WARN(1, "Failed to allocate memory: dyndbg may not work properly.\n");
>   		break;
> @@ -1556,7 +1555,8 @@ static int __init dynamic_debug_init(void)
>   			mod_ct++;
>   			di.descs.len = mod_sites;
>   			di.descs.start = iter_mod_start;
> -			ret = ddebug_add_module(&di, modname);
> +			di.mod_name = modname;
> +			ret = ddebug_add_module(&di);
>   			if (ret)
>   				goto out_err;
>   
> @@ -1567,7 +1567,8 @@ static int __init dynamic_debug_init(void)
>   	}
>   	di.descs.len = mod_sites;
>   	di.descs.start = iter_mod_start;
> -	ret = ddebug_add_module(&di, modname);
> +	di.mod_name = modname;
> +	ret = ddebug_add_module(&di);
>   	if (ret)
>   		goto out_err;
>   

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