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)