Re: [PATCH] EDAC: core EDAC support code

[Andrew Morton]

Al Viro <viro@xxxxxxxxxxxxxxxx> wrote:
>
> On Mon, Mar 06, 2006 at 01:53:44PM -0800, Greg KH wrote:
>  > > 	rmmod your_turd </sys/spew/from/your_turd
>  > > and there you go.  rmmod can _NOT_ wait for sysfs references to go away.
>  > 
>  > To be fair, the only part of the kernel that supports the above process,
>  > is the network stack.  And they implemented a special kind of lock to
>  > handle just this kind of thing.
>  > 
>  > That is not something that I want the rest of the kernel to have to use.
>  > If your code blocks when doing the above thing, that's fine with me.
> 
>  One word: fail.  With -EBUSY.

It seems quite simple to make wait_for_zero_refcount() interruptible? 
Something like...



--- devel/kernel/module.c~modules-make-wait_for_zero_refcount-interruptible	2006-03-07 02:36:46.000000000 -0800
+++ devel-akpm/kernel/module.c	2006-03-07 02:39:18.000000000 -0800
@@ -578,8 +578,8 @@ static void wait_for_zero_refcount(struc
 	mutex_unlock(&module_mutex);
 	for (;;) {
 		DEBUGP("Looking at refcount...\n");
-		set_current_state(TASK_UNINTERRUPTIBLE);
-		if (module_refcount(mod) == 0)
+		set_current_state(TASK_INTERRUPTIBLE);
+		if (module_refcount(mod) == 0 || signal_pending(current))
 			break;
 		schedule();
 	}
@@ -645,8 +645,18 @@ sys_delete_module(const char __user *nam
 		goto out;
 
 	/* Never wait if forced. */
-	if (!forced && module_refcount(mod) != 0)
+	if (!forced && module_refcount(mod) != 0) {
 		wait_for_zero_refcount(mod);
+		if (module_refcount(mod)) {
+			/*
+			 * Signalled: back out
+			 */
+			mod->state = MODULE_STATE_LIVE;
+			mod->waiter = NULL;
+			ret = -EINTR;
+			goto out;
+		}
+	}
 
 	/* Final destruction now noone is using it. */
 	if (mod->exit != NULL) {
_

-
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