linux-kernel - [PATCH] module: remove over-zealous check in __module

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Date:	Sat, 7 Feb 2009 18:15:56 +1030
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org, Karsten Keil <kkeil@...e.de>,
	stable@...nel.org
Subject: [PATCH] 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@...e.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@...e.de>
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
---
 include/linux/module.h |    1 -
 1 file changed, 1 deletion(-)

diff --git a/include/linux/module.h b/include/linux/module.h
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -407,7 +407,6 @@ static inline void __module_get(struct m
 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();
 	}
--
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