Re: [PATCH] rmmod notifier chain

[Tom Rini <trini@kernel.crashing.org>]

On Thu, Sep 08, 2005 at 05:03:58PM +0200, Jan Beulich wrote:

> (Note: Patch also attached because the inline version is certain to get
> line wrapped.)
> 
> Debugging and maintenance support code occasionally needs to know not
> only of module insertions, but also modulke removals. This adds a
> notifier
> chain for this purpose.

It's possible to do this a bit differently, if I'm guessing right at
what NLKD does.  The following is from the KGDB patches (trimmed of some
other, unrelated to the notify part code):

diff -puN include/linux/module.h~module include/linux/module.h
--- linux-2.6.13/include/linux/module.h~module	2005-09-01 12:00:49.000000000 -0700
+++ linux-2.6.13-trini/include/linux/module.h	2005-09-01 12:00:49.000000000 -0700
@@ -210,6 +210,7 @@ enum module_state
 	MODULE_STATE_LIVE,
 	MODULE_STATE_COMING,
 	MODULE_STATE_GOING,
+ 	MODULE_STATE_GONE,
 };
 
 /* Similar stuff for section attributes. */
diff -puN kernel/module.c~module kernel/module.c
--- linux-2.6.13/kernel/module.c~module	2005-09-01 12:00:49.000000000 -0700
+++ linux-2.6.13-trini/kernel/module.c	2005-09-01 12:00:49.000000000 -0700
@@ -623,6 +623,12 @@ sys_delete_module(const char __user *nam
 	if (ret != 0)
 		goto out;
 
+	down(&notify_mutex);
+	notifier_call_chain(&module_notify_list, MODULE_STATE_GOING,
+        			mod);
+	up(&notify_mutex);
+
+
 	/* Never wait if forced. */
 	if (!forced && module_refcount(mod) != 0)
 		wait_for_zero_refcount(mod);
@@ -635,6 +641,11 @@ sys_delete_module(const char __user *nam
 	}
 	free_module(mod);
 
+	down(&notify_mutex);
+	notifier_call_chain(&module_notify_list, MODULE_STATE_GONE,
+			NULL);
+	up(&notify_mutex);
+
  out:
 	up(&module_mutex);
 	return ret;
@@ -1909,6 +1961,10 @@ sys_init_module(void __user *umod,
 		/* Init routine failed: abort.  Try to protect us from
                    buggy refcounters. */
 		mod->state = MODULE_STATE_GOING;
+		down(&notify_mutex);
+		notifier_call_chain(&module_notify_list, MODULE_STATE_GOING,
+				mod);
+		up(&notify_mutex);
 		synchronize_sched();
 		if (mod->unsafe)
 			printk(KERN_ERR "%s: module is now stuck!\n",
_
-- 
Tom Rini
http://gate.crashing.org/~trini/