[PATCH 1/2] parport: fix attempt to write duplicate procfiles

[PATCH 1/2] parport: fix attempt to write duplicate procfiles

[Sudip Mukherjee]

Usually every parallel port will have a single pardev registered with
it. But ppdev driver is an exception. This userspace parallel port
driver allows to create multiple parrallel port devices for a single
parallel port. And as a result we were having a nice warning like:
"sysctl table check failed:
/dev/parport/parport0/devices/ppdev0/timeslice Sysctl already exists"

Use the same logic as used in parport_register_device() and register
the proc files only once for each parallel port.

Fixes: 6fa45a226897 ("parport: add device-model to parport subsystem")
Cc: stable <stable@vger.kernel.org> # v4.4+
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1414656
Bugzilla: https://bugs.archlinux.org/task/52322
Tested-by: James Feeney <james@nurealm.net>
Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
---
 drivers/parport/share.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/parport/share.c b/drivers/parport/share.c
index bc090da..5dc53d4 100644
--- a/drivers/parport/share.c
+++ b/drivers/parport/share.c
@@ -939,8 +939,10 @@ parport_register_dev_model(struct parport *port, const char *name,
 	 * pardevice fields. -arca
 	 */
 	port->ops->init_state(par_dev, par_dev->state);
-	port->proc_device = par_dev;
-	parport_device_proc_register(par_dev);
+	if (!test_and_set_bit(PARPORT_DEVPROC_REGISTERED, &port->devflags)) {
+		port->proc_device = par_dev;
+		parport_device_proc_register(par_dev);
+	}
 
 	return par_dev;
 
-- 
2.1.4

[PATCH 2/2] ppdev: fix registering same device name

[Sudip Mukherjee]

Usually every parallel port will have a single pardev registered with
it. But ppdev driver is an exception. This userspace parallel port
driver allows to create multiple parrallel port devices for a single
parallel port. And as a result we were having a big warning like:
"sysfs: cannot create duplicate filename '/devices/parport0/ppdev0.0'".
And with that many parallel port printers stopped working.

We have been using the minor number as the id field while registering
a parralel port device with a parralel port. But when there are
multiple parrallel port device for one single parallel port, they all
tried to register with the same name like 'pardev0.0' and everything
started failing.
Use an incremented index as the id instead of the minor number.

Fixes: 8b7d3a9d903e ("ppdev: use new parport device model")
Cc: stable <stable@vger.kernel.org> # v4.9+
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1414656
Bugzilla: https://bugs.archlinux.org/task/52322
Tested-by: James Feeney <james@nurealm.net>
Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
---
 drivers/char/ppdev.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/char/ppdev.c b/drivers/char/ppdev.c
index 2a558c7..3e73bcd 100644
--- a/drivers/char/ppdev.c
+++ b/drivers/char/ppdev.c
@@ -84,11 +84,14 @@ struct pp_struct {
 	struct ieee1284_info state;
 	struct ieee1284_info saved_state;
 	long default_inactivity;
+	int index;
 };
 
 /* should we use PARDEVICE_MAX here? */
 static struct device *devices[PARPORT_MAX];
 
+static DEFINE_IDA(ida_index);
+
 /* pp_struct.flags bitfields */
 #define PP_CLAIMED    (1<<0)
 #define PP_EXCL       (1<<1)
@@ -290,7 +293,7 @@ static int register_device(int minor, struct pp_struct *pp)
 	struct pardevice *pdev = NULL;
 	char *name;
 	struct pardev_cb ppdev_cb;
-	int rc = 0;
+	int rc = 0, index;
 
 	name = kasprintf(GFP_KERNEL, CHRDEV "%x", minor);
 	if (name == NULL)
@@ -303,20 +306,23 @@ static int register_device(int minor, struct pp_struct *pp)
 		goto err;
 	}
 
+	index = ida_simple_get(&ida_index, 0, 0, GFP_KERNEL);
 	memset(&ppdev_cb, 0, sizeof(ppdev_cb));
 	ppdev_cb.irq_func = pp_irq;
 	ppdev_cb.flags = (pp->flags & PP_EXCL) ? PARPORT_FLAG_EXCL : 0;
 	ppdev_cb.private = pp;
-	pdev = parport_register_dev_model(port, name, &ppdev_cb, minor);
+	pdev = parport_register_dev_model(port, name, &ppdev_cb, index);
 	parport_put_port(port);
 
 	if (!pdev) {
 		pr_warn("%s: failed to register device!\n", name);
 		rc = -ENXIO;
+		ida_simple_remove(&ida_index, index);
 		goto err;
 	}
 
 	pp->pdev = pdev;
+	pp->index = index;
 	dev_dbg(&pdev->dev, "registered pardevice\n");
 err:
 	kfree(name);
@@ -755,6 +761,7 @@ static int pp_release(struct inode *inode, struct file *file)
 
 	if (pp->pdev) {
 		parport_unregister_device(pp->pdev);
+		ida_simple_remove(&ida_index, pp->index);
 		pp->pdev = NULL;
 		pr_debug(CHRDEV "%x: unregistered pardevice\n", minor);
 	}
-- 
2.1.4