[media] em28xx: Only deallocate struct em28xx after finishing all extensions

We can't free struct em28xx while one of the extensions is still
using it.

So, add a kref() to control it, freeing it only after the
extensions fini calls.

Reviewed-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

1 files changed, 25 insertions, 7 deletions

diff --git a/drivers/media/usb/em28xx/em28xx-cards.c b/drivers/media/usb/em28xx/em28xx-cards.c
index 2fb300e882f0..e7ec3b7866f1 100644
--- a/drivers/media/usb/em28xx/em28xx-cards.c
+++ b/drivers/media/usb/em28xx/em28xx-cards.c
@@ -2939,7 +2939,7 @@ static void flush_request_modules(struct em28xx *dev)
  * unregisters the v4l2,i2c and usb devices
  * called when the device gets disconnected or at module unload
 */
-void em28xx_release_resources(struct em28xx *dev)
+static void em28xx_release_resources(struct em28xx *dev)
 {
         /*FIXME: I2C IR should be disconnected */
 
@@ -2956,7 +2956,27 @@ void em28xx_release_resources(struct em28xx *dev)
 
         mutex_unlock(&dev->lock);
 };
-EXPORT_SYMBOL_GPL(em28xx_release_resources);
+
+/**
+ * em28xx_free_device() - Free em28xx device
+ *
+ * @ref: struct kref for em28xx device
+ *
+ * This is called when all extensions and em28xx core unregisters a device
+ */
+void em28xx_free_device(struct kref *ref)
+{
+        struct em28xx *dev = kref_to_dev(ref);
+
+        em28xx_info("Freeing device\n");
+
+        if (!dev->disconnected)
+                em28xx_release_resources(dev);
+
+        kfree(dev->alt_max_pkt_size_isoc);
+        kfree(dev);
+}
+EXPORT_SYMBOL_GPL(em28xx_free_device);
 
 /*
  * em28xx_init_dev()
@@ -3409,6 +3429,8 @@ static int em28xx_usb_probe(struct usb_interface *interface,
                             dev->dvb_xfer_bulk ? "bulk" : "isoc");
         }
 
+        kref_init(&dev->ref);
+
         request_modules(dev);
 
         /* Should be the last thing to do, to avoid newer udev's to
@@ -3453,11 +3475,7 @@ static void em28xx_usb_disconnect(struct usb_interface *interface)
         em28xx_close_extension(dev);
 
         em28xx_release_resources(dev);
-
-        if (!dev->users) {
-                kfree(dev->alt_max_pkt_size_isoc);
-                kfree(dev);
-        }
+        kref_put(&dev->ref, em28xx_free_device);
 }
 
 static int em28xx_usb_suspend(struct usb_interface *interface,