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Date:      Wed, 25 May 2016 07:48:36 +0000 (UTC)
From:      Hans Petter Selasky <hselasky@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r300667 - head/sys/dev/usb
Message-ID:  <201605250748.u4P7ma5F030925@repo.freebsd.org>
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Author: hselasky
Date: Wed May 25 07:48:36 2016
New Revision: 300667
URL: https://svnweb.freebsd.org/changeset/base/300667

Log:
  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.
  
  MFC after:	1 week

Modified:
  head/sys/dev/usb/usb_dev.c
  head/sys/dev/usb/usb_device.c
  head/sys/dev/usb/usb_device.h

Modified: head/sys/dev/usb/usb_dev.c
==============================================================================
--- head/sys/dev/usb/usb_dev.c	Wed May 25 07:43:32 2016	(r300666)
+++ head/sys/dev/usb/usb_dev.c	Wed May 25 07:48:36 2016	(r300667)
@@ -228,7 +228,7 @@ usb_ref_device(struct usb_cdev_privdata 
 		 * 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);
 
@@ -236,6 +236,12 @@ usb_ref_device(struct usb_cdev_privdata 
 		 * 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 */

Modified: head/sys/dev/usb/usb_device.c
==============================================================================
--- head/sys/dev/usb/usb_device.c	Wed May 25 07:43:32 2016	(r300666)
+++ head/sys/dev/usb/usb_device.c	Wed May 25 07:48:36 2016	(r300667)
@@ -2740,7 +2740,7 @@ usbd_device_attached(struct usb_device *
 /*
  * 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

Modified: head/sys/dev/usb/usb_device.h
==============================================================================
--- head/sys/dev/usb/usb_device.h	Wed May 25 07:43:32 2016	(r300666)
+++ head/sys/dev/usb/usb_device.h	Wed May 25 07:48:36 2016	(r300667)
@@ -314,6 +314,9 @@ void	usb_set_device_state(struct usb_dev
 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 *);

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