[PATCH] parport: quickfix the proc registration bug

[PATCH] parport: quickfix the proc registration bug

[Alan Cox]

From: Alan Cox <alan@etchedpixels.co.uk>

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 <alan@linux.intel.com>
---

 drivers/parport/share.c |   13 ++++++++++---
 include/linux/parport.h |    4 ++++
 2 files changed, 14 insertions(+), 3 deletions(-)


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];
 };

Re: [PATCH] parport: quickfix the proc registration bug

[Frans Pop]

Alan Cox wrote:
> 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 <alan@linux.intel.com>

Thanks Alan. Unfortunately I'm no longer able to test this as my printer 
is now connected via USB to my notebook's docking station instead of via 
a parport to my desktop (which was prompted to home server and moved to a 
different room).