MFC r300667:

Check for signals when locking the USB enumeration thread from
userspace, so that USB applications can be killed if an enumeration
thread should be stuck for various reasons.

3 files changed, 32 insertions, 2 deletions

diff --git a/sys/dev/usb/usb_dev.c b/sys/dev/usb/usb_dev.c
index 7231230..2973fa4 100644
--- a/sys/dev/usb/usb_dev.c
+++ b/sys/dev/usb/usb_dev.c
@@ -229,7 +229,7 @@ usb_ref_device(struct usb_cdev_privdata *cpd,
 		 * We need to grab the enumeration SX-lock before
 		 * grabbing the FIFO refs to avoid deadlock at detach!
 		 */
-		crd->do_unlock = usbd_enum_lock(cpd->udev);
+		crd->do_unlock = usbd_enum_lock_sig(cpd->udev);
 
 		mtx_lock(&usb_ref_lock);
 
@@ -237,6 +237,12 @@ usb_ref_device(struct usb_cdev_privdata *cpd,
 		 * Set "is_uref" after grabbing the default SX lock
 		 */
 		crd->is_uref = 1;
+
+		/* check for signal */
+		if (crd->do_unlock > 1) {
+			crd->do_unlock = 0;
+			goto error;
+		}
 	}
 
 	/* check if we are doing an open */
diff --git a/sys/dev/usb/usb_device.c b/sys/dev/usb/usb_device.c
index bd62009..639d461 100644
--- a/sys/dev/usb/usb_device.c
+++ b/sys/dev/usb/usb_device.c
@@ -2740,7 +2740,7 @@ usbd_device_attached(struct usb_device *udev)
 /*
  * The following function locks enumerating the given USB device. If
  * the lock is already grabbed this function returns zero. Else a
- * non-zero value is returned.
+ * a value of one is returned.
  */
 uint8_t
 usbd_enum_lock(struct usb_device *udev)
@@ -2759,6 +2759,27 @@ usbd_enum_lock(struct usb_device *udev)
 	return (1);
 }
 
+#if USB_HAVE_UGEN
+/*
+ * This function is the same like usbd_enum_lock() except a value of
+ * 255 is returned when a signal is pending:
+ */
+uint8_t
+usbd_enum_lock_sig(struct usb_device *udev)
+{
+	if (sx_xlocked(&udev->enum_sx))
+		return (0);
+	if (sx_xlock_sig(&udev->enum_sx))
+		return (255);
+	if (sx_xlock_sig(&udev->sr_sx)) {
+		sx_xunlock(&udev->enum_sx);
+		return (255);
+	}
+	mtx_lock(&Giant);
+	return (1);
+}
+#endif
+
 /* The following function unlocks enumerating the given USB device. */
 
 void
diff --git a/sys/dev/usb/usb_device.h b/sys/dev/usb/usb_device.h
index 5a94998..7a979bb 100644
--- a/sys/dev/usb/usb_device.h
+++ b/sys/dev/usb/usb_device.h
@@ -314,6 +314,9 @@ void	usb_set_device_state(struct usb_device *, enum usb_dev_state);
 enum usb_dev_state usb_get_device_state(struct usb_device *);
 
 uint8_t	usbd_enum_lock(struct usb_device *);
+#if USB_HAVE_UGEN
+uint8_t	usbd_enum_lock_sig(struct usb_device *);
+#endif
 void	usbd_enum_unlock(struct usb_device *);
 void	usbd_sr_lock(struct usb_device *);
 void	usbd_sr_unlock(struct usb_device *);