linux-kernel - [PATCH 1/2] modules: Fix module waiting for dependent modules' init.

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Message-Id: <200803042321.01683.rusty@rustcorp.com.au>
Date:	Tue, 4 Mar 2008 23:21:01 +1100
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Jan Glauber <jang@...ux.vnet.ibm.com>
Cc:	Miles Lane <miles.lane@...il.com>,
	LKML <linux-kernel@...r.kernel.org>, linux-usb@...r.kernel.org
Subject: [PATCH 1/2] modules: Fix module waiting for dependent modules' init.

Commit c9a3ba55 (module: wait for dependent modules doing init.)
didn't quite work because the waiter holds the module lock, meaning
that the state of the module it's waiting for cannot change.

Fortunately, it's fairly simple to update the state outside the lock
and do the wakeup.

Thanks to Jan Glauber <jang@...ux.vnet.ibm.com> for tracking this down
and testing (qdio and qeth).

Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
---
 kernel/module.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff -r 1198dd206438 kernel/module.c
--- a/kernel/module.c	Tue Mar 04 11:18:59 2008 +1100
+++ b/kernel/module.c	Tue Mar 04 13:23:22 2008 +1100
@@ -2172,9 +2172,11 @@ sys_init_module(void __user *umod,
 		return ret;
 	}
 
-	/* Now it's a first class citizen! */
+	/* Now it's a first class citizen!  Wake up anyone waiting for it. */
+	mod->state = MODULE_STATE_LIVE;
+	wake_up(&module_wq);
+
 	mutex_lock(&module_mutex);
-	mod->state = MODULE_STATE_LIVE;
 	/* Drop initial reference. */
 	module_put(mod);
 	unwind_remove_table(mod->unwind_info, 1);
@@ -2183,7 +2185,6 @@ sys_init_module(void __user *umod,
 	mod->init_size = 0;
 	mod->init_text_size = 0;
 	mutex_unlock(&module_mutex);
-	wake_up(&module_wq);
 
 	return 0;
 }
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