Subject: parport: quickfix the proc registration bug
From: Alan Cox <[email-masked]>
Date: Tue, 2 Jun 2009 15:58:10 +0000 (+0100)

parport: quickfix the proc registration bug

Ideally we should have a directory of drivers and a link to the 'active'
driver. For now just show the first device which is effectively the existing
semantics without a warning.

This is an update on the original buggy patch that I then forgot to
resubmit. Confusingly it was proposed by Red Hat, written by Etched Pixels
fixed and submitted by Intel ...

Resolves-Bug: http://bugzilla.kernel.org/show_bug.cgi?id=9749
Signed-off-by: Alan Cox <[email-masked]>
Signed-off-by: Linus Torvalds <[email-masked]>
---

diff --git a/drivers/parport/share.c b/drivers/parport/share.c
index 0ebca45..dffa5d4 100644
--- a/drivers/parport/share.c
+++ b/drivers/parport/share.c
@@ -614,7 +614,10 @@ parport_register_device(struct parport *port, const char *name,
 	 * pardevice fields. -arca
 	 */
 	port->ops->init_state(tmp, tmp->state);
-	parport_device_proc_register(tmp);
+	if (!test_and_set_bit(PARPORT_DEVPROC_REGISTERED, &port->devflags)) {
+		port->proc_device = tmp;
+		parport_device_proc_register(tmp);
+	}
 	return tmp;
 
  out_free_all:
@@ -646,10 +649,14 @@ void parport_unregister_device(struct pardevice *dev)
 	}
 #endif
 
-	parport_device_proc_unregister(dev);
-
 	port = dev->port->physport;
 
+	if (port->proc_device == dev) {
+		port->proc_device = NULL;
+		clear_bit(PARPORT_DEVPROC_REGISTERED, &port->devflags);
+		parport_device_proc_unregister(dev);
+	}
+
 	if (port->cad == dev) {
 		printk(KERN_DEBUG "%s: %s forgot to release port\n",
 		       port->name, dev->name);
diff --git a/include/linux/parport.h b/include/linux/parport.h
index e1f83c5..38a423e 100644
--- a/include/linux/parport.h
+++ b/include/linux/parport.h
@@ -324,6 +324,10 @@ struct parport {
 	int spintime;
 	atomic_t ref_count;
 
+	unsigned long devflags;
+#define PARPORT_DEVPROC_REGISTERED	0
+	struct pardevice *proc_device;	/* Currently register proc device */
+
 	struct list_head full_list;
 	struct parport *slaves[3];
 };