Re: [PATCH] rmmod notifier chain

[Tom Rini]

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/
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