ppdev: check before attaching port

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.

Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 21 insertions, 2 deletions

diff --git a/drivers/char/ppdev.c b/drivers/char/ppdev.c
index 85c63e49df7f..02819e0703c8 100644
--- a/drivers/char/ppdev.c
+++ b/drivers/char/ppdev.c
@@ -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_fops = {
 
 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)