Patch "ppdev: check before attaching port" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

ppdev: check before attaching port

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
ppdev-check-before-attaching-port.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Sudip Mukherjee <[email protected]>
Date: Sat, 12 Nov 2016 21:22:12 +0000
Subject: ppdev: check before attaching port

From: Sudip Mukherjee <[email protected]>

commit dd5c472a60e43549d789a17a8444513eec64bd7e upstream.

After parport starts using the device model, all pardevice drivers should decide in their match_port callback function if they want to attach with that particulatr port. ppdev has been converted to use the new parport device-model code but pp_attach() tried to attach with all the ports.
Create a new array of pointer and use that to remember the ports we have attached. And use that information to skip attaching ports which we have already attached.

---
 drivers/char/ppdev.c |   23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

@@ -86,6 +86,9 @@ struct pp_struct {
 	long default_inactivity;
 };
 
+/* should we use PARDEVICE_MAX here? */
+static struct device *devices[PARPORT_MAX];
+
 /* pp_struct.flags bitfields */
 #define PP_CLAIMED    (1<<0)
 #define PP_EXCL       (1<<1)

@@ -789,13 +792,29 @@ static const struct file_operations pp_f
 
 static void pp_attach(struct parport *port)
 {
-	device_create(ppdev_class, port->dev, MKDEV(PP_MAJOR, port->number),
-		      NULL, "parport%d", port->number);
+	struct device *ret;
+
+	if (devices[port->number])
+		return;
+
+	ret = device_create(ppdev_class, port->dev,
+			    MKDEV(PP_MAJOR, port->number), NULL,
+			    "parport%d", port->number);
+	if (IS_ERR(ret)) {
+		pr_err("Failed to create device parport%d\n",
+		       port->number);
+		return;
+	}
+	devices[port->number] = ret;
 }
 
 static void pp_detach(struct parport *port)
 {
+	if (!devices[port->number])
+		return;
+
 	device_destroy(ppdev_class, MKDEV(PP_MAJOR, port->number));
+	devices[port->number] = NULL;
 }
 
 static int pp_probe(struct pardevice *par_dev)

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/ppdev-check-before-attaching-port.patch queue-4.9/ppdev-fix-registering-same-device-name.patch