[media] em28xx-dvb: stop URBs when stopping the streaming

Stop the URBs in em28xx_stop_streaming(), so that em28xx_irq_callback()
cannot be called after the streaming has stopped.

This should eliminate the crashes reported by Antti Palosaari and the warnings
reported by Andy Furniss.
Signed-off-by: Gianluca Gennari <gennarone@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/em28xx/em28xx-core.c

@@ -666,7 +666,6 @@ int em28xx_capture_start(struct em28xx *dev, int start)
 
 	return rc;
 }
-EXPORT_SYMBOL_GPL(em28xx_capture_start);
 
 int em28xx_vbi_supported(struct em28xx *dev)
 {
@@ -1007,6 +1006,31 @@ void em28xx_uninit_isoc(struct em28xx *dev, enum em28xx_mode mode)
 }
 EXPORT_SYMBOL_GPL(em28xx_uninit_isoc);
 
+/*
+ * Stop URBs
+ */
+void em28xx_stop_urbs(struct em28xx *dev)
+{
+	int i;
+	struct urb *urb;
+	struct em28xx_usb_isoc_bufs *isoc_bufs = &dev->isoc_ctl.digital_bufs;
+
+	em28xx_isocdbg("em28xx: called em28xx_stop_urbs\n");
+
+	for (i = 0; i < isoc_bufs->num_bufs; i++) {
+		urb = isoc_bufs->urb[i];
+		if (urb) {
+			if (!irqs_disabled())
+				usb_kill_urb(urb);
+			else
+				usb_unlink_urb(urb);
+		}
+	}
+
+	em28xx_capture_start(dev, 0);
+}
+EXPORT_SYMBOL_GPL(em28xx_stop_urbs);
+
 /*
  * Allocate URBs
  */

drivers/media/video/em28xx/em28xx-dvb.c

@@ -183,7 +183,7 @@ static int em28xx_stop_streaming(struct em28xx_dvb *dvb)
 {
 	struct em28xx *dev = dvb->adapter.priv;
 
-	em28xx_capture_start(dev, 0);
+	em28xx_stop_urbs(dev);
 
 	em28xx_set_mode(dev, EM28XX_SUSPEND);
 

drivers/media/video/em28xx/em28xx.h

@@ -695,6 +695,7 @@ int em28xx_init_isoc(struct em28xx *dev, enum em28xx_mode mode,
 		     int max_packets, int num_bufs, int max_pkt_size,
 		     int (*isoc_copy) (struct em28xx *dev, struct urb *urb));
 void em28xx_uninit_isoc(struct em28xx *dev, enum em28xx_mode mode);
+void em28xx_stop_urbs(struct em28xx *dev);
 int em28xx_isoc_dvb_max_packetsize(struct em28xx *dev);
 int em28xx_set_mode(struct em28xx *dev, enum em28xx_mode set_mode);
 int em28xx_gpio_set(struct em28xx *dev, struct em28xx_reg_seq *gpio);