Merge branch 'next' (accumulated 3.16 merge window patches) into master

Now that 3.15 is released, this merges the 'next' branch into 'master',
bringing us to the normal situation where my 'master' branch is the
merge window.

* accumulated work in next: (6809 commits)
  ufs: sb mutex merge + mutex_destroy
  powerpc: update comments for generic idle conversion
  cris: update comments for generic idle conversion
  idle: remove cpu_idle() forward declarations
  nbd: zero from and len fields in NBD_CMD_DISCONNECT.
  mm: convert some level-less printks to pr_*
  MAINTAINERS: adi-buildroot-devel is moderated
  MAINTAINERS: add linux-api for review of API/ABI changes
  mm/kmemleak-test.c: use pr_fmt for logging
  fs/dlm/debug_fs.c: replace seq_printf by seq_puts
  fs/dlm/lockspace.c: convert simple_str to kstr
  fs/dlm/config.c: convert simple_str to kstr
  mm: mark remap_file_pages() syscall as deprecated
  mm: memcontrol: remove unnecessary memcg argument from soft limit functions
  mm: memcontrol: clean up memcg zoneinfo lookup
  mm/memblock.c: call kmemleak directly from memblock_(alloc|free)
  mm/mempool.c: update the kmemleak stack trace for mempool allocations
  lib/radix-tree.c: update the kmemleak stack trace for radix tree allocations
  mm: introduce kmemleak_update_trace()
  mm/kmemleak.c: use %u to print ->checksum
  ...

1 files changed, 11 insertions, 4 deletions

diff --git a/drivers/usb/misc/appledisplay.c b/drivers/usb/misc/appledisplay.c
index ba6a5d6e618..b3d245ef46e 100644
--- a/drivers/usb/misc/appledisplay.c
+++ b/drivers/usb/misc/appledisplay.c
@@ -81,6 +81,7 @@ struct appledisplay {
 	struct delayed_work work;
 	int button_pressed;
 	spinlock_t lock;
+	struct mutex sysfslock;		/* concurrent read and write */
 };
 
 static atomic_t count_displays = ATOMIC_INIT(0);
@@ -110,7 +111,7 @@ static void appledisplay_complete(struct urb *urb)
 			__func__, status);
 		return;
 	default:
-		dev_dbg(dev, "%s - nonzero urb status received: %d/n",
+		dev_dbg(dev, "%s - nonzero urb status received: %d\n",
 			__func__, status);
 		goto exit;
 	}
@@ -144,6 +145,7 @@ static int appledisplay_bl_update_status(struct backlight_device *bd)
 	struct appledisplay *pdata = bl_get_data(bd);
 	int retval;
 
+	mutex_lock(&pdata->sysfslock);
 	pdata->msgdata[0] = 0x10;
 	pdata->msgdata[1] = bd->props.brightness;
 
@@ -156,15 +158,17 @@ static int appledisplay_bl_update_status(struct backlight_device *bd)
 		0,
 		pdata->msgdata, 2,
 		ACD_USB_TIMEOUT);
-
+	mutex_unlock(&pdata->sysfslock);
+	
 	return retval;
 }
 
 static int appledisplay_bl_get_brightness(struct backlight_device *bd)
 {
 	struct appledisplay *pdata = bl_get_data(bd);
-	int retval;
+	int retval, brightness;
 
+	mutex_lock(&pdata->sysfslock);
 	retval = usb_control_msg(
 		pdata->udev,
 		usb_rcvctrlpipe(pdata->udev, 0),
@@ -174,11 +178,13 @@ static int appledisplay_bl_get_brightness(struct backlight_device *bd)
 		0,
 		pdata->msgdata, 2,
 		ACD_USB_TIMEOUT);
+	brightness = pdata->msgdata[1];
+	mutex_unlock(&pdata->sysfslock);
 
 	if (retval < 0)
 		return retval;
 	else
-		return pdata->msgdata[1];
+		return brightness;
 }
 
 static const struct backlight_ops appledisplay_bl_data = {
@@ -241,6 +247,7 @@ static int appledisplay_probe(struct usb_interface *iface,
 
 	spin_lock_init(&pdata->lock);
 	INIT_DELAYED_WORK(&pdata->work, appledisplay_work);
+	mutex_init(&pdata->sysfslock);
 
 	/* Allocate buffer for control messages */
 	pdata->msgdata = kmalloc(ACD_MSG_BUFFER_LEN, GFP_KERNEL);