[PATCH 0/3] USB: idmouse: disconnect clean ups

[PATCH 0/3] USB: idmouse: disconnect clean ups

[Johan Hovold]

The idmouse driver does not suffer from the disconnect-related bugs
recently fixed in the other misc drivers. It does however have some
redundant constructs in place to manage the open-disconnect race, which
is already taken care of by USB core.

Johan


Johan Hovold (3):
  USB: idmouse: simplify disconnect handling
  USB: idmouse: drop redundant open-count check from release
  USB: idmouse: clean up runaway white space

 drivers/usb/misc/idmouse.c | 36 +++++++-----------------------------
 1 file changed, 7 insertions(+), 29 deletions(-)

-- 
2.23.0

[PATCH 1/3] USB: idmouse: simplify disconnect handling

[Johan Hovold]

Since commit d4ead16f50f9 ("USB: prevent char device open/deregister
race") core prevents further calls to open() after usb_deregister_dev()
returns so there's no need to use the interface data for
synchronisation.

This effectively reverts commit 54d2bc068fd2 ("USB: fix locking in
idmouse") with respect to the open-disconnect race.

Note that the driver already uses a present flag to suppress I/O post
disconnect (even if all USB I/O take place at open).

Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/misc/idmouse.c | 20 ++------------------
 1 file changed, 2 insertions(+), 18 deletions(-)

diff --git a/drivers/usb/misc/idmouse.c b/drivers/usb/misc/idmouse.c
index 20b0f91a5d9b..0386bac224c4 100644
--- a/drivers/usb/misc/idmouse.c
+++ b/drivers/usb/misc/idmouse.c
@@ -60,7 +60,6 @@ static const struct usb_device_id idmouse_table[] = {
 	USB_TYPE_VENDOR | USB_RECIP_ENDPOINT | USB_DIR_OUT, value, index, NULL, 0, 1000)
 
 MODULE_DEVICE_TABLE(usb, idmouse_table);
-static DEFINE_MUTEX(open_disc_mutex);
 
 /* structure to hold all of our device specific stuff */
 struct usb_idmouse {
@@ -227,17 +226,13 @@ static int idmouse_open(struct inode *inode, struct file *file)
 	if (!interface)
 		return -ENODEV;
 
-	mutex_lock(&open_disc_mutex);
 	/* get the device information block from the interface */
 	dev = usb_get_intfdata(interface);
-	if (!dev) {
-		mutex_unlock(&open_disc_mutex);
+	if (!dev)
 		return -ENODEV;
-	}
 
 	/* lock this device */
 	mutex_lock(&dev->lock);
-	mutex_unlock(&open_disc_mutex);
 
 	/* check if already open */
 	if (dev->open) {
@@ -280,14 +275,12 @@ static int idmouse_release(struct inode *inode, struct file *file)
 	if (dev == NULL)
 		return -ENODEV;
 
-	mutex_lock(&open_disc_mutex);
 	/* lock our device */
 	mutex_lock(&dev->lock);
 
 	/* are we really open? */
 	if (dev->open <= 0) {
 		mutex_unlock(&dev->lock);
-		mutex_unlock(&open_disc_mutex);
 		return -ENODEV;
 	}
 
@@ -296,11 +289,9 @@ static int idmouse_release(struct inode *inode, struct file *file)
 	if (!dev->present) {
 		/* the device was unplugged before the file was released */
 		mutex_unlock(&dev->lock);
-		mutex_unlock(&open_disc_mutex);
 		idmouse_delete(dev);
 	} else {
 		mutex_unlock(&dev->lock);
-		mutex_unlock(&open_disc_mutex);
 	}
 	return 0;
 }
@@ -379,7 +370,6 @@ static int idmouse_probe(struct usb_interface *interface,
 	if (result) {
 		/* something prevented us from registering this device */
 		dev_err(&interface->dev, "Unable to allocate minor number.\n");
-		usb_set_intfdata(interface, NULL);
 		idmouse_delete(dev);
 		return result;
 	}
@@ -392,19 +382,13 @@ static int idmouse_probe(struct usb_interface *interface,
 
 static void idmouse_disconnect(struct usb_interface *interface)
 {
-	struct usb_idmouse *dev;
-
-	/* get device structure */
-	dev = usb_get_intfdata(interface);
+	struct usb_idmouse *dev = usb_get_intfdata(interface);
 
 	/* give back our minor */
 	usb_deregister_dev(interface, &idmouse_class);
 
-	mutex_lock(&open_disc_mutex);
-	usb_set_intfdata(interface, NULL);
 	/* lock the device */
 	mutex_lock(&dev->lock);
-	mutex_unlock(&open_disc_mutex);
 
 	/* prevent device read, write and ioctl */
 	dev->present = 0;
-- 
2.23.0

[PATCH 2/3] USB: idmouse: drop redundant open-count check from release

[Johan Hovold]

The open count will always be exactly one when release is called, so
drop the redundant sanity check.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/misc/idmouse.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/drivers/usb/misc/idmouse.c b/drivers/usb/misc/idmouse.c
index 0386bac224c4..9b9d5df829d5 100644
--- a/drivers/usb/misc/idmouse.c
+++ b/drivers/usb/misc/idmouse.c
@@ -278,12 +278,6 @@ static int idmouse_release(struct inode *inode, struct file *file)
 	/* lock our device */
 	mutex_lock(&dev->lock);
 
-	/* are we really open? */
-	if (dev->open <= 0) {
-		mutex_unlock(&dev->lock);
-		return -ENODEV;
-	}
-
 	--dev->open;
 
 	if (!dev->present) {
-- 
2.23.0

[PATCH 3/3] USB: idmouse: clean up runaway white space

[Johan Hovold]

Drop space between function identifiers and opening parenthesis, which
was no longer even used consistently within the driver.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/misc/idmouse.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/misc/idmouse.c b/drivers/usb/misc/idmouse.c
index 9b9d5df829d5..4afb5ddfd361 100644
--- a/drivers/usb/misc/idmouse.c
+++ b/drivers/usb/misc/idmouse.c
@@ -56,7 +56,7 @@ static const struct usb_device_id idmouse_table[] = {
 #define FTIP_SCROLL  0x24
 
 #define ftip_command(dev, command, value, index) \
-	usb_control_msg (dev->udev, usb_sndctrlpipe (dev->udev, 0), command, \
+	usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, 0), command, \
 	USB_TYPE_VENDOR | USB_RECIP_ENDPOINT | USB_DIR_OUT, value, index, NULL, 0, 1000)
 
 MODULE_DEVICE_TABLE(usb, idmouse_table);
@@ -157,8 +157,8 @@ static int idmouse_create_image(struct usb_idmouse *dev)
 
 	/* loop over a blocking bulk read to get data from the device */
 	while (bytes_read < IMGSIZE) {
-		result = usb_bulk_msg (dev->udev,
-				usb_rcvbulkpipe (dev->udev, dev->bulk_in_endpointAddr),
+		result = usb_bulk_msg(dev->udev,
+				usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr),
 				dev->bulk_in_buffer + bytes_read,
 				dev->bulk_in_size, &bulk_read, 5000);
 		if (result < 0) {
@@ -222,7 +222,7 @@ static int idmouse_open(struct inode *inode, struct file *file)
 	int result;
 
 	/* get the interface from minor number and driver information */
-	interface = usb_find_interface (&idmouse_driver, iminor (inode));
+	interface = usb_find_interface(&idmouse_driver, iminor(inode));
 	if (!interface)
 		return -ENODEV;
 
@@ -246,7 +246,7 @@ static int idmouse_open(struct inode *inode, struct file *file)
 		result = usb_autopm_get_interface(interface);
 		if (result)
 			goto error;
-		result = idmouse_create_image (dev);
+		result = idmouse_create_image(dev);
 		usb_autopm_put_interface(interface);
 		if (result)
 			goto error;
-- 
2.23.0