V4L/DVB (9086): gspca: Use a kref to avoid potentialy blocking forever in disconnect.

Signed-off-by: Frank Zago <frank@zago.net>
Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

2 files changed, 28 insertions, 12 deletions

diff --git a/drivers/media/video/gspca/gspca.c b/drivers/media/video/gspca/gspca.c
index 3f0fd44f19ab..342a0f39e5d5 100644
--- a/drivers/media/video/gspca/gspca.c
+++ b/drivers/media/video/gspca/gspca.c
@@ -29,6 +29,7 @@
 #include <linux/string.h>
 #include <linux/pagemap.h>
 #include <linux/io.h>
+#include <linux/kref.h>
 #include <asm/page.h>
 #include <linux/uaccess.h>
 #include <linux/jiffies.h>
@@ -834,6 +835,16 @@ out:
         return ret;
 }
 
+static void gspca_delete(struct kref *kref)
+{
+        struct gspca_dev *gspca_dev = container_of(kref, struct gspca_dev, kref);
+
+        PDEBUG(D_STREAM, "device deleted");
+
+        kfree(gspca_dev->usb_buf);
+        kfree(gspca_dev);
+}
+
 static int dev_open(struct inode *inode, struct file *file)
 {
         struct gspca_dev *gspca_dev;
@@ -853,6 +864,10 @@ static int dev_open(struct inode *inode, struct file *file)
                 goto out;
         }
         gspca_dev->users++;
+
+        /* one more user */
+        kref_get(&gspca_dev->kref);
+
         file->private_data = gspca_dev;
 #ifdef GSPCA_DEBUG
         /* activate the v4l2 debug */
@@ -895,7 +910,11 @@ static int dev_close(struct inode *inode, struct file *file)
         }
         file->private_data = NULL;
         mutex_unlock(&gspca_dev->queue_lock);
+
         PDEBUG(D_STREAM, "close done");
+
+        kref_put(&gspca_dev->kref, gspca_delete);
+
         return 0;
 }
 
@@ -1809,6 +1828,7 @@ int gspca_dev_probe(struct usb_interface *intf,
                 err("couldn't kzalloc gspca struct");
                 return -EIO;
         }
+        kref_init(&gspca_dev->kref);
         gspca_dev->usb_buf = kmalloc(USB_BUF_SZ, GFP_KERNEL);
         if (!gspca_dev->usb_buf) {
                 err("out of memory");
@@ -1858,8 +1878,7 @@ int gspca_dev_probe(struct usb_interface *intf,
         PDEBUG(D_PROBE, "probe ok");
         return 0;
 out:
-        kfree(gspca_dev->usb_buf);
-        kfree(gspca_dev);
+        kref_put(&gspca_dev->kref, gspca_delete);
         return ret;
 }
 EXPORT_SYMBOL(gspca_dev_probe);
@@ -1874,8 +1893,8 @@ void gspca_disconnect(struct usb_interface *intf)
 {
         struct gspca_dev *gspca_dev = usb_get_intfdata(intf);
 
-        if (!gspca_dev)
-                return;
+        usb_set_intfdata(intf, NULL);
+
         gspca_dev->present = 0;
         mutex_lock(&gspca_dev->queue_lock);
         mutex_lock(&gspca_dev->usb_lock);
@@ -1883,16 +1902,12 @@ void gspca_disconnect(struct usb_interface *intf)
         destroy_urbs(gspca_dev);
         mutex_unlock(&gspca_dev->usb_lock);
         mutex_unlock(&gspca_dev->queue_lock);
-        while (gspca_dev->users != 0) {         /* wait until fully closed */
-                atomic_inc(&gspca_dev->nevent);
-                wake_up_interruptible(&gspca_dev->wq);  /* wake processes */
-                schedule();
-        }
+
 /* We don't want people trying to open up the device */
         video_unregister_device(&gspca_dev->vdev);
-/* Free the memory */
-        kfree(gspca_dev->usb_buf);
-        kfree(gspca_dev);
+
+        kref_put(&gspca_dev->kref, gspca_delete);
+
         PDEBUG(D_PROBE, "disconnect complete");
 }
 EXPORT_SYMBOL(gspca_disconnect);
diff --git a/drivers/media/video/gspca/gspca.h b/drivers/media/video/gspca/gspca.h
index b0bdae194bb6..192dffdcd9cd 100644
--- a/drivers/media/video/gspca/gspca.h
+++ b/drivers/media/video/gspca/gspca.h
@@ -121,6 +121,7 @@ struct gspca_dev {
         struct video_device vdev;       /* !! must be the first item */
         struct file_operations fops;
         struct usb_device *dev;
+        struct kref kref;
         struct file *capt_file;         /* file doing video capture */
 
         struct cam cam;                         /* device information */