From: Stefani Seibold <stefani@xxxxxxxxxxx>
Most USB devices can only used in a single usage mode. This patch
prevents a reopening on an already opened device.
Signed-off-by: Stefani Seibold <stefani@xxxxxxxxxxx>
---
drivers/usb/usb-skeleton.c | 9 +++++++++
1 files changed, 9 insertions(+), 0 deletions(-)
diff --git a/drivers/usb/usb-skeleton.c b/drivers/usb/usb-skeleton.c
index 11cc97b..81d256f 100644
--- a/drivers/usb/usb-skeleton.c
+++ b/drivers/usb/usb-skeleton.c
@@ -61,6 +61,7 @@ struct usb_skel {
int errors; /* the last request tanked */
bool ongoing_read; /* a read is going on */
bool connected; /* connected flag */
+ bool in_use; /* in use flag */
spinlock_t err_lock; /* lock for errors */
struct kref kref;
struct mutex io_mutex; /* synchronize with disconnect */
@@ -104,6 +105,11 @@ static int skel_open(struct inode *inode, struct file *file)
goto exit;
}
+ if (dev->in_use) {
+ retval = -EBUSY;
+ goto exit;
+ }
+
retval = usb_autopm_get_interface(interface);
if (retval)
goto exit;
@@ -111,6 +117,7 @@ static int skel_open(struct inode *inode, struct file *file)
/* increment our usage count for the device */
kref_get(&dev->kref);
+ dev->in_use = true;
mutex_unlock(&sync_mutex);
/* save our object in the file's private structure */
@@ -131,6 +138,7 @@ static int skel_release(struct inode *inode, struct file *file)
if (dev->connected)
usb_autopm_put_interface(
usb_find_interface(&skel_driver, iminor(inode)));
+ dev->in_use = false;
/* decrement the count on our device */
kref_put(&dev->kref, skel_delete);
@@ -529,6 +537,7 @@ static int skel_probe(struct usb_interface *interface,
dev->udev = usb_get_dev(interface_to_usbdev(interface));
dev->connected = true;
+ dev->in_use = false;
/* set up the endpoint information */
/* use only the first bulk-in and bulk-out endpoints */
--
1.7.8.6
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