Merge branch 'percpu-for-linus' into percpu-for-next

Conflicts:
	arch/sparc/kernel/smp_64.c
	arch/x86/kernel/cpu/perf_counter.c
	arch/x86/kernel/setup_percpu.c
	drivers/cpufreq/cpufreq_ondemand.c
	mm/percpu.c

Conflicts in core and arch percpu codes are mostly from commit
ed78e1e078dd44249f88b1dd8c76dafb39567161 which substituted many
num_possible_cpus() with nr_cpu_ids.  As for-next branch has moved all
the first chunk allocators into mm/percpu.c, the changes are moved
from arch code to mm/percpu.c.

Signed-off-by: Tejun Heo <tj@kernel.org>

9 files changed, 167 insertions, 96 deletions

diff --git a/drivers/usb/core/Kconfig b/drivers/usb/core/Kconfig
index 69280c35b5cb..ad925946f869 100644
--- a/drivers/usb/core/Kconfig
+++ b/drivers/usb/core/Kconfig
@@ -28,7 +28,7 @@ comment "Miscellaneous USB options"
 	depends on USB
 
 config USB_DEVICEFS
-	bool "USB device filesystem (DEPRECATED)" if EMBEDDED
+	bool "USB device filesystem (DEPRECATED)"
 	depends on USB
 	---help---
 	  If you say Y here (and to "/proc file system support" in the "File
diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c
index 24dfb33f90cb..a16c538d0132 100644
--- a/drivers/usb/core/config.c
+++ b/drivers/usb/core/config.c
@@ -80,38 +80,18 @@ static int usb_parse_ss_endpoint_companion(struct device *ddev, int cfgno,
 	int max_tx;
 	int i;
 
-	/* Allocate space for the SS endpoint companion descriptor */
-	ep->ss_ep_comp = kzalloc(sizeof(struct usb_host_ss_ep_comp),
-			GFP_KERNEL);
-	if (!ep->ss_ep_comp)
-		return -ENOMEM;
 	desc = (struct usb_ss_ep_comp_descriptor *) buffer;
 	if (desc->bDescriptorType != USB_DT_SS_ENDPOINT_COMP) {
 		dev_warn(ddev, "No SuperSpeed endpoint companion for config %d "
 				" interface %d altsetting %d ep %d: "
 				"using minimum values\n",
 				cfgno, inum, asnum, ep->desc.bEndpointAddress);
-		ep->ss_ep_comp->desc.bLength = USB_DT_SS_EP_COMP_SIZE;
-		ep->ss_ep_comp->desc.bDescriptorType = USB_DT_SS_ENDPOINT_COMP;
-		ep->ss_ep_comp->desc.bMaxBurst = 0;
-		/*
-		 * Leave bmAttributes as zero, which will mean no streams for
-		 * bulk, and isoc won't support multiple bursts of packets.
-		 * With bursts of only one packet, and a Mult of 1, the max
-		 * amount of data moved per endpoint service interval is one
-		 * packet.
-		 */
-		if (usb_endpoint_xfer_isoc(&ep->desc) ||
-				usb_endpoint_xfer_int(&ep->desc))
-			ep->ss_ep_comp->desc.wBytesPerInterval =
-				ep->desc.wMaxPacketSize;
 		/*
 		 * The next descriptor is for an Endpoint or Interface,
 		 * no extra descriptors to copy into the companion structure,
 		 * and we didn't eat up any of the buffer.
 		 */
-		retval = 0;
-		goto valid;
+		return 0;
 	}
 	memcpy(&ep->ss_ep_comp->desc, desc, USB_DT_SS_EP_COMP_SIZE);
 	desc = &ep->ss_ep_comp->desc;
@@ -320,6 +300,28 @@ static int usb_parse_endpoint(struct device *ddev, int cfgno, int inum,
 		buffer += i;
 		size -= i;
 
+		/* Allocate space for the SS endpoint companion descriptor */
+		endpoint->ss_ep_comp = kzalloc(sizeof(struct usb_host_ss_ep_comp),
+				GFP_KERNEL);
+		if (!endpoint->ss_ep_comp)
+			return -ENOMEM;
+
+		/* Fill in some default values (may be overwritten later) */
+		endpoint->ss_ep_comp->desc.bLength = USB_DT_SS_EP_COMP_SIZE;
+		endpoint->ss_ep_comp->desc.bDescriptorType = USB_DT_SS_ENDPOINT_COMP;
+		endpoint->ss_ep_comp->desc.bMaxBurst = 0;
+		/*
+		 * Leave bmAttributes as zero, which will mean no streams for
+		 * bulk, and isoc won't support multiple bursts of packets.
+		 * With bursts of only one packet, and a Mult of 1, the max
+		 * amount of data moved per endpoint service interval is one
+		 * packet.
+		 */
+		if (usb_endpoint_xfer_isoc(&endpoint->desc) ||
+				usb_endpoint_xfer_int(&endpoint->desc))
+			endpoint->ss_ep_comp->desc.wBytesPerInterval =
+				endpoint->desc.wMaxPacketSize;
+
 		if (size > 0) {
 			retval = usb_parse_ss_endpoint_companion(ddev, cfgno,
 					inum, asnum, endpoint, num_ep, buffer,
@@ -329,6 +331,10 @@ static int usb_parse_endpoint(struct device *ddev, int cfgno, int inum,
 				retval = buffer - buffer0;
 			}
 		} else {
+			dev_warn(ddev, "config %d interface %d altsetting %d "
+				"endpoint 0x%X has no "
+				"SuperSpeed companion descriptor\n",
+				cfgno, inum, asnum, d->bEndpointAddress);
 			retval = buffer - buffer0;
 		}
 	} else {
diff --git a/drivers/usb/core/devices.c b/drivers/usb/core/devices.c
index 73c108d117b4..96f11715cd26 100644
--- a/drivers/usb/core/devices.c
+++ b/drivers/usb/core/devices.c
@@ -136,17 +136,19 @@ static const struct class_info clas_info[] =
 	{USB_CLASS_AUDIO,		"audio"},
 	{USB_CLASS_COMM,		"comm."},
 	{USB_CLASS_HID,			"HID"},
-	{USB_CLASS_HUB,			"hub"},
 	{USB_CLASS_PHYSICAL,		"PID"},
+	{USB_CLASS_STILL_IMAGE,		"still"},
 	{USB_CLASS_PRINTER,		"print"},
 	{USB_CLASS_MASS_STORAGE,	"stor."},
+	{USB_CLASS_HUB,			"hub"},
 	{USB_CLASS_CDC_DATA,		"data"},
-	{USB_CLASS_APP_SPEC,		"app."},
-	{USB_CLASS_VENDOR_SPEC,		"vend."},
-	{USB_CLASS_STILL_IMAGE,		"still"},
 	{USB_CLASS_CSCID,		"scard"},
 	{USB_CLASS_CONTENT_SEC,		"c-sec"},
 	{USB_CLASS_VIDEO,		"video"},
+	{USB_CLASS_WIRELESS_CONTROLLER,	"wlcon"},
+	{USB_CLASS_MISC,		"misc"},
+	{USB_CLASS_APP_SPEC,		"app."},
+	{USB_CLASS_VENDOR_SPEC,		"vend."},
 	{-1,				"unk."}		/* leave as last */
 };
 
diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index 308609039c73..4247eccf858c 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -325,21 +325,34 @@ static void async_completed(struct urb *urb)
 	struct async *as = urb->context;
 	struct dev_state *ps = as->ps;
 	struct siginfo sinfo;
+	struct pid *pid = NULL;
+	uid_t uid = 0;
+	uid_t euid = 0;
+	u32 secid = 0;
+	int signr;
 
 	spin_lock(&ps->lock);
 	list_move_tail(&as->asynclist, &ps->async_completed);
-	spin_unlock(&ps->lock);
 	as->status = urb->status;
-	if (as->signr) {
+	signr = as->signr;
+	if (signr) {
 		sinfo.si_signo = as->signr;
 		sinfo.si_errno = as->status;
 		sinfo.si_code = SI_ASYNCIO;
 		sinfo.si_addr = as->userurb;
-		kill_pid_info_as_uid(as->signr, &sinfo, as->pid, as->uid,
-				      as->euid, as->secid);
+		pid = as->pid;
+		uid = as->uid;
+		euid = as->euid;
+		secid = as->secid;
 	}
 	snoop(&urb->dev->dev, "urb complete\n");
 	snoop_urb(urb, as->userurb);
+	spin_unlock(&ps->lock);
+
+	if (signr)
+		kill_pid_info_as_uid(sinfo.si_signo, &sinfo, pid, uid,
+				      euid, secid);
+
 	wake_up(&ps->wait);
 }
 
@@ -582,7 +595,7 @@ static int usbdev_open(struct inode *inode, struct file *file)
 	if (!ps)
 		goto out;
 
-	ret = -ENOENT;
+	ret = -ENODEV;
 
 	/* usbdev device-node */
 	if (imajor(inode) == USB_DEVICE_MAJOR)
@@ -982,7 +995,7 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
 				USBDEVFS_URB_ZERO_PACKET |
 				USBDEVFS_URB_NO_INTERRUPT))
 		return -EINVAL;
-	if (!uurb->buffer)
+	if (uurb->buffer_length > 0 && !uurb->buffer)
 		return -EINVAL;
 	if (!(uurb->type == USBDEVFS_URB_TYPE_CONTROL &&
 	    (uurb->endpoint & ~USB_ENDPOINT_DIR_MASK) == 0)) {
@@ -1038,11 +1051,6 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
 			is_in = 0;
 			uurb->endpoint &= ~USB_DIR_IN;
 		}
-		if (!access_ok(is_in ? VERIFY_WRITE : VERIFY_READ,
-				uurb->buffer, uurb->buffer_length)) {
-			kfree(dr);
-			return -EFAULT;
-		}
 		snoop(&ps->dev->dev, "control urb: bRequest=%02x "
 			"bRrequestType=%02x wValue=%04x "
 			"wIndex=%04x wLength=%04x\n",
@@ -1062,9 +1070,6 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
 		uurb->number_of_packets = 0;
 		if (uurb->buffer_length > MAX_USBFS_BUFFER_SIZE)
 			return -EINVAL;
-		if (!access_ok(is_in ? VERIFY_WRITE : VERIFY_READ,
-				uurb->buffer, uurb->buffer_length))
-			return -EFAULT;
 		snoop(&ps->dev->dev, "bulk urb\n");
 		break;
 
@@ -1106,28 +1111,35 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
 			return -EINVAL;
 		if (uurb->buffer_length > MAX_USBFS_BUFFER_SIZE)
 			return -EINVAL;
-		if (!access_ok(is_in ? VERIFY_WRITE : VERIFY_READ,
-				uurb->buffer, uurb->buffer_length))
-			return -EFAULT;
 		snoop(&ps->dev->dev, "interrupt urb\n");
 		break;
 
 	default:
 		return -EINVAL;
 	}
-	as = alloc_async(uurb->number_of_packets);
-	if (!as) {
+	if (uurb->buffer_length > 0 &&
+			!access_ok(is_in ? VERIFY_WRITE : VERIFY_READ,
+				uurb->buffer, uurb->buffer_length)) {
 		kfree(isopkt);
 		kfree(dr);
-		return -ENOMEM;
+		return -EFAULT;
 	}
-	as->urb->transfer_buffer = kmalloc(uurb->buffer_length, GFP_KERNEL);
-	if (!as->urb->transfer_buffer) {
+	as = alloc_async(uurb->number_of_packets);
+	if (!as) {
 		kfree(isopkt);
 		kfree(dr);
-		free_async(as);
 		return -ENOMEM;
 	}
+	if (uurb->buffer_length > 0) {
+		as->urb->transfer_buffer = kmalloc(uurb->buffer_length,
+				GFP_KERNEL);
+		if (!as->urb->transfer_buffer) {
+			kfree(isopkt);
+			kfree(dr);
+			free_async(as);
+			return -ENOMEM;
+		}
+	}
 	as->urb->dev = ps->dev;
 	as->urb->pipe = (uurb->type << 30) |
 			__create_pipe(ps->dev, uurb->endpoint & 0xf) |
@@ -1169,7 +1181,7 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
 	kfree(isopkt);
 	as->ps = ps;
 	as->userurb = arg;
-	if (uurb->endpoint & USB_DIR_IN)
+	if (is_in && uurb->buffer_length > 0)
 		as->userbuffer = uurb->buffer;
 	else
 		as->userbuffer = NULL;
@@ -1179,9 +1191,9 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
 	as->uid = cred->uid;
 	as->euid = cred->euid;
 	security_task_getsecid(current, &as->secid);
-	if (!is_in) {
+	if (!is_in && uurb->buffer_length > 0) {
 		if (copy_from_user(as->urb->transfer_buffer, uurb->buffer,
-				as->urb->transfer_buffer_length)) {
+				uurb->buffer_length)) {
 			free_async(as);
 			return -EFAULT;
 		}
@@ -1231,22 +1243,22 @@ static int processcompl(struct async *as, void __user * __user *arg)
 	if (as->userbuffer)
 		if (copy_to_user(as->userbuffer, urb->transfer_buffer,
 				 urb->transfer_buffer_length))
-			return -EFAULT;
+			goto err_out;
 	if (put_user(as->status, &userurb->status))
-		return -EFAULT;
+		goto err_out;
 	if (put_user(urb->actual_length, &userurb->actual_length))
-		return -EFAULT;
+		goto err_out;
 	if (put_user(urb->error_count, &userurb->error_count))
-		return -EFAULT;
+		goto err_out;
 
 	if (usb_endpoint_xfer_isoc(&urb->ep->desc)) {
 		for (i = 0; i < urb->number_of_packets; i++) {
 			if (put_user(urb->iso_frame_desc[i].actual_length,
 				     &userurb->iso_frame_desc[i].actual_length))
-				return -EFAULT;
+				goto err_out;
 			if (put_user(urb->iso_frame_desc[i].status,
 				     &userurb->iso_frame_desc[i].status))
-				return -EFAULT;
+				goto err_out;
 		}
 	}
 
@@ -1255,6 +1267,10 @@ static int processcompl(struct async *as, void __user * __user *arg)
 	if (put_user(addr, (void __user * __user *)arg))
 		return -EFAULT;
 	return 0;
+
+err_out:
+	free_async(as);
+	return -EFAULT;
 }
 
 static struct async *reap_as(struct dev_state *ps)
@@ -1305,7 +1321,8 @@ static int get_urb32(struct usbdevfs_urb *kurb,
 		     struct usbdevfs_urb32 __user *uurb)
 {
 	__u32  uptr;
-	if (get_user(kurb->type, &uurb->type) ||
+	if (!access_ok(VERIFY_READ, uurb, sizeof(*uurb)) ||
+	    __get_user(kurb->type, &uurb->type) ||
 	    __get_user(kurb->endpoint, &uurb->endpoint) ||
 	    __get_user(kurb->status, &uurb->status) ||
 	    __get_user(kurb->flags, &uurb->flags) ||
@@ -1520,8 +1537,9 @@ static int proc_ioctl_compat(struct dev_state *ps, compat_uptr_t arg)
 	u32 udata;
 
 	uioc = compat_ptr((long)arg);
-	if (get_user(ctrl.ifno, &uioc->ifno) ||
-	    get_user(ctrl.ioctl_code, &uioc->ioctl_code) ||
+	if (!access_ok(VERIFY_READ, uioc, sizeof(*uioc)) ||
+	    __get_user(ctrl.ifno, &uioc->ifno) ||
+	    __get_user(ctrl.ioctl_code, &uioc->ioctl_code) ||
 	    __get_user(udata, &uioc->data))
 		return -EFAULT;
 	ctrl.data = compat_ptr(udata);
diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index ce3f453f02ef..95ccfa0b9fc5 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -648,7 +648,7 @@ void usb_hcd_poll_rh_status(struct usb_hcd *hcd)
 	struct urb	*urb;
 	int		length;
 	unsigned long	flags;
-	char		buffer[4];	/* Any root hubs with > 31 ports? */
+	char		buffer[6];	/* Any root hubs with > 31 ports? */
 
 	if (unlikely(!hcd->rh_registered))
 		return;
diff --git a/drivers/usb/core/hcd.h b/drivers/usb/core/hcd.h
index d397ecfd5b17..ec5c67ea07b7 100644
--- a/drivers/usb/core/hcd.h
+++ b/drivers/usb/core/hcd.h
@@ -227,6 +227,10 @@ struct hc_driver {
 		/* has a port been handed over to a companion? */
 	int	(*port_handed_over)(struct usb_hcd *, int);
 
+		/* CLEAR_TT_BUFFER completion callback */
+	void	(*clear_tt_buffer_complete)(struct usb_hcd *,
+				struct usb_host_endpoint *);
+
 	/* xHCI specific functions */
 		/* Called by usb_alloc_dev to alloc HC device structures */
 	int	(*alloc_dev)(struct usb_hcd *, struct usb_device *);
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 2af3b4f06054..71f86c60d83c 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -450,10 +450,10 @@ hub_clear_tt_buffer (struct usb_device *hdev, u16 devinfo, u16 tt)
  * talking to TTs must queue control transfers (not just bulk and iso), so
  * both can talk to the same hub concurrently.
  */
-static void hub_tt_kevent (struct work_struct *work)
+static void hub_tt_work(struct work_struct *work)
 {
 	struct usb_hub		*hub =
-		container_of(work, struct usb_hub, tt.kevent);
+		container_of(work, struct usb_hub, tt.clear_work);
 	unsigned long		flags;
 	int			limit = 100;
 
@@ -462,6 +462,7 @@ static void hub_tt_kevent (struct work_struct *work)
 		struct list_head	*next;
 		struct usb_tt_clear	*clear;
 		struct usb_device	*hdev = hub->hdev;
+		const struct hc_driver	*drv;
 		int			status;
 
 		next = hub->tt.clear_list.next;
@@ -471,21 +472,25 @@ static void hub_tt_kevent (struct work_struct *work)
 		/* drop lock so HCD can concurrently report other TT errors */
 		spin_unlock_irqrestore (&hub->tt.lock, flags);
 		status = hub_clear_tt_buffer (hdev, clear->devinfo, clear->tt);
-		spin_lock_irqsave (&hub->tt.lock, flags);
-
 		if (status)
 			dev_err (&hdev->dev,
 				"clear tt %d (%04x) error %d\n",
 				clear->tt, clear->devinfo, status);
+
+		/* Tell the HCD, even if the operation failed */
+		drv = clear->hcd->driver;
+		if (drv->clear_tt_buffer_complete)
+			(drv->clear_tt_buffer_complete)(clear->hcd, clear->ep);
+
 		kfree(clear);
+		spin_lock_irqsave(&hub->tt.lock, flags);
 	}
 	spin_unlock_irqrestore (&hub->tt.lock, flags);
 }
 
 /**
- * usb_hub_tt_clear_buffer - clear control/bulk TT state in high speed hub
- * @udev: the device whose split transaction failed
- * @pipe: identifies the endpoint of the failed transaction
+ * usb_hub_clear_tt_buffer - clear control/bulk TT state in high speed hub
+ * @urb: an URB associated with the failed or incomplete split transaction
  *
  * High speed HCDs use this to tell the hub driver that some split control or
  * bulk transaction failed in a way that requires clearing internal state of
@@ -495,8 +500,10 @@ static void hub_tt_kevent (struct work_struct *work)
  * It may not be possible for that hub to handle additional full (or low)
  * speed transactions until that state is fully cleared out.
  */
-void usb_hub_tt_clear_buffer (struct usb_device *udev, int pipe)
+int usb_hub_clear_tt_buffer(struct urb *urb)
 {
+	struct usb_device	*udev = urb->dev;
+	int			pipe = urb->pipe;
 	struct usb_tt		*tt = udev->tt;
 	unsigned long		flags;
 	struct usb_tt_clear	*clear;
@@ -508,7 +515,7 @@ void usb_hub_tt_clear_buffer (struct usb_device *udev, int pipe)
 	if ((clear = kmalloc (sizeof *clear, GFP_ATOMIC)) == NULL) {
 		dev_err (&udev->dev, "can't save CLEAR_TT_BUFFER state\n");
 		/* FIXME recover somehow ... RESET_TT? */
-		return;
+		return -ENOMEM;
 	}
 
 	/* info that CLEAR_TT_BUFFER needs */
@@ -520,14 +527,19 @@ void usb_hub_tt_clear_buffer (struct usb_device *udev, int pipe)
 			: (USB_ENDPOINT_XFER_BULK << 11);
 	if (usb_pipein (pipe))
 		clear->devinfo |= 1 << 15;
-	
+
+	/* info for completion callback */
+	clear->hcd = bus_to_hcd(udev->bus);
+	clear->ep = urb->ep;
+
 	/* tell keventd to clear state for this TT */
 	spin_lock_irqsave (&tt->lock, flags);
 	list_add_tail (&clear->clear_list, &tt->clear_list);
-	schedule_work (&tt->kevent);
+	schedule_work(&tt->clear_work);
 	spin_unlock_irqrestore (&tt->lock, flags);
+	return 0;
 }
-EXPORT_SYMBOL_GPL(usb_hub_tt_clear_buffer);
+EXPORT_SYMBOL_GPL(usb_hub_clear_tt_buffer);
 
 /* If do_delay is false, return the number of milliseconds the caller
  * needs to delay.
@@ -818,7 +830,7 @@ static void hub_quiesce(struct usb_hub *hub, enum hub_quiescing_type type)
 	if (hub->has_indicators)
 		cancel_delayed_work_sync(&hub->leds);
 	if (hub->tt.hub)
-		cancel_work_sync(&hub->tt.kevent);
+		cancel_work_sync(&hub->tt.clear_work);
 }
 
 /* caller has locked the hub device */
@@ -935,7 +947,7 @@ static int hub_configure(struct usb_hub *hub,
 
 	spin_lock_init (&hub->tt.lock);
 	INIT_LIST_HEAD (&hub->tt.clear_list);
-	INIT_WORK (&hub->tt.kevent, hub_tt_kevent);
+	INIT_WORK(&hub->tt.clear_work, hub_tt_work);
 	switch (hdev->descriptor.bDeviceProtocol) {
 		case 0:
 			break;
diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h
index 889c0f32a40b..de8081f065ed 100644
--- a/drivers/usb/core/hub.h
+++ b/drivers/usb/core/hub.h
@@ -188,16 +188,18 @@ struct usb_tt {
 	/* for control/bulk error recovery (CLEAR_TT_BUFFER) */
 	spinlock_t		lock;
 	struct list_head	clear_list;	/* of usb_tt_clear */
-	struct work_struct			kevent;
+	struct work_struct	clear_work;
 };
 
 struct usb_tt_clear {
 	struct list_head	clear_list;
 	unsigned		tt;
 	u16			devinfo;
+	struct usb_hcd		*hcd;
+	struct usb_host_endpoint	*ep;
 };
 
-extern void usb_hub_tt_clear_buffer(struct usb_device *dev, int pipe);
+extern int usb_hub_clear_tt_buffer(struct urb *urb);
 extern void usb_ep0_reinit(struct usb_device *);
 
 #endif /* __LINUX_HUB_H */
diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index 2bed83caacb1..9720e699f472 100644
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -806,6 +806,48 @@ static int usb_string_sub(struct usb_device *dev, unsigned int langid,
 	return rc;
 }
 
+static int usb_get_langid(struct usb_device *dev, unsigned char *tbuf)
+{
+	int err;
+
+	if (dev->have_langid)
+		return 0;
+
+	if (dev->string_langid < 0)
+		return -EPIPE;
+
+	err = usb_string_sub(dev, 0, 0, tbuf);
+
+	/* If the string was reported but is malformed, default to english
+	 * (0x0409) */
+	if (err == -ENODATA || (err > 0 && err < 4)) {
+		dev->string_langid = 0x0409;
+		dev->have_langid = 1;
+		dev_err(&dev->dev,
+			"string descriptor 0 malformed (err = %d), "
+			"defaulting to 0x%04x\n",
+				err, dev->string_langid);
+		return 0;
+	}
+
+	/* In case of all other errors, we assume the device is not able to
+	 * deal with strings at all. Set string_langid to -1 in order to
+	 * prevent any string to be retrieved from the device */
+	if (err < 0) {
+		dev_err(&dev->dev, "string descriptor 0 read error: %d\n",
+					err);
+		dev->string_langid = -1;
+		return -EPIPE;
+	}
+
+	/* always use the first langid listed */
+	dev->string_langid = tbuf[2] | (tbuf[3] << 8);
+	dev->have_langid = 1;
+	dev_dbg(&dev->dev, "default language 0x%04x\n",
+				dev->string_langid);
+	return 0;
+}
+
 /**
  * usb_string - returns UTF-8 version of a string descriptor
  * @dev: the device whose string descriptor is being retrieved
@@ -837,24 +879,9 @@ int usb_string(struct usb_device *dev, int index, char *buf, size_t size)
 	if (!tbuf)
 		return -ENOMEM;
 
-	/* get langid for strings if it's not yet known */
-	if (!dev->have_langid) {
-		err = usb_string_sub(dev, 0, 0, tbuf);
-		if (err < 0) {
-			dev_err(&dev->dev,
-				"string descriptor 0 read error: %d\n",
-				err);
-		} else if (err < 4) {
-			dev_err(&dev->dev, "string descriptor 0 too short\n");
-		} else {
-			dev->string_langid = tbuf[2] | (tbuf[3] << 8);
-			/* always use the first langid listed */
-			dev_dbg(&dev->dev, "default language 0x%04x\n",
-				dev->string_langid);
-		}
-
-		dev->have_langid = 1;
-	}
+	err = usb_get_langid(dev, tbuf);
+	if (err < 0)
+		goto errout;
 
 	err = usb_string_sub(dev, dev->string_langid, index, tbuf);
 	if (err < 0)