usb: cdc-wdm: make reset work with blocking IO

Add a flag to tell wdm_read/wdm_write that a reset is in progress,
and wake any blocking read/write before taking the mutexes.  This
allows the device to reset without waiting for blocking IO to
finish.

Signed-off-by: Bjørn Mork <bjorn@mork.no>
Acked-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 17 insertions, 4 deletions

diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c
index f63601a2054c..b27bbb957e16 100644
--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -70,6 +70,7 @@ MODULE_DEVICE_TABLE (usb, wdm_ids);
 #define WDM_POLL_RUNNING        6
 #define WDM_RESPONDING          7
 #define WDM_SUSPENDING          8
+#define WDM_RESETTING           9
 
 #define WDM_MAX                 16
 
@@ -340,6 +341,10 @@ static ssize_t wdm_write
         else
                 if (test_bit(WDM_IN_USE, &desc->flags))
                         r = -EAGAIN;
+
+        if (test_bit(WDM_RESETTING, &desc->flags))
+                r = -EIO;
+
         if (r < 0) {
                 kfree(buf);
                 goto out;
@@ -419,6 +424,10 @@ retry:
                         rv = -ENODEV;
                         goto err;
                 }
+                if (test_bit(WDM_RESETTING, &desc->flags)) {
+                        rv = -EIO;
+                        goto err;
+                }
                 usb_mark_last_busy(interface_to_usbdev(desc->intf));
                 if (rv < 0) {
                         rv = -ERESTARTSYS;
@@ -859,10 +868,6 @@ static int wdm_pre_reset(struct usb_interface *intf)
 {
         struct wdm_device *desc = usb_get_intfdata(intf);
 
-        mutex_lock(&desc->rlock);
-        mutex_lock(&desc->wlock);
-        kill_urbs(desc);
-
         /*
          * we notify everybody using poll of
          * an exceptional situation
@@ -870,9 +875,16 @@ static int wdm_pre_reset(struct usb_interface *intf)
          * message from the device is lost
          */
         spin_lock_irq(&desc->iuspin);
+        set_bit(WDM_RESETTING, &desc->flags);   /* inform read/write */
+        set_bit(WDM_READ, &desc->flags);        /* unblock read */
+        clear_bit(WDM_IN_USE, &desc->flags);    /* unblock write */
         desc->rerr = -EINTR;
         spin_unlock_irq(&desc->iuspin);
         wake_up_all(&desc->wait);
+        mutex_lock(&desc->rlock);
+        mutex_lock(&desc->wlock);
+        kill_urbs(desc);
+        cancel_work_sync(&desc->rxwork);
         return 0;
 }
 
@@ -881,6 +893,7 @@ static int wdm_post_reset(struct usb_interface *intf)
         struct wdm_device *desc = usb_get_intfdata(intf);
         int rv;
 
+        clear_bit(WDM_RESETTING, &desc->flags);
         rv = recover_from_urb_loss(desc);
         mutex_unlock(&desc->wlock);
         mutex_unlock(&desc->rlock);