module: remove over-zealous check in __module_get()

Impact: fix spurious BUG_ON() triggered under load

module_refcount() isn't reliable outside stop_machine(), as demonstrated
by Karsten Keil <kkeil@suse.de>, networking can trigger it under load
(an inc on one cpu and dec on another while module_refcount() is tallying
 can give false results, for example).

Almost noone should be using __module_get, but that's another issue.

Cc: Karsten Keil <kkeil@suse.de>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/module.h b/include/linux/module.h
index f3b8329eb5b877d7233ab66d566dd280fc78536c..145a75528cc1868c275bbbcfacb97ab0124eab46 100644 (file)
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -407,7 +407,6 @@ static inline local_t *__module_ref_addr(struct module *mod, int cpu)
 static inline void __module_get(struct module *module)
 {
        if (module) {
-               BUG_ON(module_refcount(module) == 0);
                local_inc(__module_ref_addr(module, get_cpu()));
                put_cpu();
        }