dynamic_debug: use pointer comparison in ddebug_remove_module

Now that we store the passed-in string directly in ddebug_add_module, we
can use pointer equality instead of strcmp.  This is a little more
efficient, but more importantly, this also makes the code somewhat more
correct:

Currently, if one loads and then unloads a module whose name happens to
match the KBUILD_MODNAME of some built-in functionality (which need not
even be modular at all), all of their dynamic debug entries vanish along
with those of the actual module.  For example, loading and unloading a
core.ko hides all pr_debugs from drivers/base/core.c and other built-in
files called core.c (incidentally, there is an in-tree module whose name
is core, but I just tested this with an out-of-tree trivial one).

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Rasmus Villemoes <[email protected]>
Acked-by: Jason Baron <[email protected]>
Cc: David Sterba <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Petr Mladek <[email protected]>
Cc: "Rafael J . Wysocki" <[email protected]>
Cc: Steven Rostedt <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 8274c4ea75e0450ad0b115db30fc3de520ed726e..214828c656251292e405e34415f786dd95b499ac 100644 (file)
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -929,9 +929,10 @@ int ddebug_remove_module(const char *mod_name)
 
        mutex_lock(&ddebug_lock);
        list_for_each_entry_safe(dt, nextdt, &ddebug_tables, link) {
-               if (!strcmp(dt->mod_name, mod_name)) {
+               if (dt->mod_name == mod_name) {
                        ddebug_table_free(dt);
                        ret = 0;
+                       break;
                }
        }
        mutex_unlock(&ddebug_lock);