USB: extension of anchor API to unpoison an anchor

This extension allows unpoisoning an anchor allowing drivers that
resubmit URBs to reuse an anchor for methods like resume()

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 21 insertions, 0 deletions

diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
index b5e9948698bf..58bc5e3c2560 100644
--- a/drivers/usb/core/urb.c
+++ b/drivers/usb/core/urb.c
@@ -679,6 +679,26 @@ void usb_poison_anchored_urbs(struct usb_anchor *anchor)
 EXPORT_SYMBOL_GPL(usb_poison_anchored_urbs);
 
 /**
+ * usb_unpoison_anchored_urbs - let an anchor be used successfully again
+ * @anchor: anchor the requests are bound to
+ *
+ * Reverses the effect of usb_poison_anchored_urbs
+ * the anchor can be used normally after it returns
+ */
+void usb_unpoison_anchored_urbs(struct usb_anchor *anchor)
+{
+        unsigned long flags;
+        struct urb *lazarus;
+
+        spin_lock_irqsave(&anchor->lock, flags);
+        list_for_each_entry(lazarus, &anchor->urb_list, anchor_list) {
+                usb_unpoison_urb(lazarus);
+        }
+        anchor->poisoned = 0;
+        spin_unlock_irqrestore(&anchor->lock, flags);
+}
+EXPORT_SYMBOL_GPL(usb_unpoison_anchored_urbs);
+/**
  * usb_unlink_anchored_urbs - asynchronously cancel transfer requests en masse
  * @anchor: anchor the requests are bound to
  *
diff --git a/include/linux/usb.h b/include/linux/usb.h
index 4e8654a18250..e89639896508 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -1485,6 +1485,7 @@ extern void usb_poison_urb(struct urb *urb);
 extern void usb_unpoison_urb(struct urb *urb);
 extern void usb_kill_anchored_urbs(struct usb_anchor *anchor);
 extern void usb_poison_anchored_urbs(struct usb_anchor *anchor);
+extern void usb_unpoison_anchored_urbs(struct usb_anchor *anchor);
 extern void usb_unlink_anchored_urbs(struct usb_anchor *anchor);
 extern void usb_anchor_urb(struct urb *urb, struct usb_anchor *anchor);
 extern void usb_unanchor_urb(struct urb *urb);