[PATCH v2 08/23] dynamic_debug: don't duplicate modname in ddebug_add_module

[Rasmus Villemoes]

For built-in modules, we're already reusing the passed-in string via
kstrdup_const(). But for actual modules (i.e. when we're called from
dynamic_debug_setup in module.c), the passed-in string (which points
at the name[] array inside struct module) is also
guaranteed to live at least as long as the struct ddebug_table, since
free_module() calls ddebug_remove_module().

Acked-by: Jason Baron <jba...@akamai.com>
Signed-off-by: Rasmus Villemoes <li...@rasmusvillemoes.dk>
---
 lib/dynamic_debug.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index c7c96bc7654a..2155e0e23530 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -847,17 +847,17 @@ int ddebug_add_module(struct _ddebug *tab, unsigned int n,
                             const char *name)
 {
        struct ddebug_table *dt;
-       const char *new_name;
 
        dt = kzalloc(sizeof(*dt), GFP_KERNEL);
        if (dt == NULL)
                return -ENOMEM;
-       new_name = kstrdup_const(name, GFP_KERNEL);
-       if (new_name == NULL) {
-               kfree(dt);
-               return -ENOMEM;
-       }
-       dt->mod_name = new_name;
+       /*
+        * 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.
+        */
+       dt->mod_name = name;
        dt->num_ddebugs = n;
        dt->ddebugs = tab;
 
@@ -913,7 +913,6 @@ int ddebug_dyndbg_module_param_cb(char *param, char *val, 
const char *module)
 static void ddebug_table_free(struct ddebug_table *dt)
 {
        list_del_init(&dt->link);
-       kfree_const(dt->mod_name);
        kfree(dt);
 }
 
-- 
2.19.1.3.g1d92a00e68