USB: introduce usb_anchor
- introduction of usb_anchor and its methods
Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
index 94ea972..ac4273d 100644
--- a/drivers/usb/core/urb.c
+++ b/drivers/usb/core/urb.c
@@ -4,6 +4,7 @@
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/usb.h>
+#include <linux/wait.h>
#include "hcd.h"
#define to_urb(d) container_of(d, struct urb, kref)
@@ -11,6 +12,7 @@
static void urb_destroy(struct kref *kref)
{
struct urb *urb = to_urb(kref);
+
kfree(urb);
}
@@ -34,6 +36,7 @@
memset(urb, 0, sizeof(*urb));
kref_init(&urb->kref);
spin_lock_init(&urb->lock);
+ INIT_LIST_HEAD(&urb->anchor_list);
}
}
@@ -100,8 +103,60 @@
kref_get(&urb->kref);
return urb;
}
-
-
+
+/**
+ * usb_anchor_urb - anchors an URB while it is processed
+ * @urb: pointer to the urb to anchor
+ * @anchor: pointer to the anchor
+ *
+ * This can be called to have access to URBs which are to be executed
+ * without bothering to track them
+ */
+void usb_anchor_urb(struct urb *urb, struct usb_anchor *anchor)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&anchor->lock, flags);
+ usb_get_urb(urb);
+ list_add_tail(&urb->anchor_list, &anchor->urb_list);
+ urb->anchor = anchor;
+ spin_unlock_irqrestore(&anchor->lock, flags);
+}
+EXPORT_SYMBOL_GPL(usb_anchor_urb);
+
+/**
+ * usb_unanchor_urb - unanchors an URB
+ * @urb: pointer to the urb to anchor
+ *
+ * Call this to stop the system keeping track of this URB
+ */
+void usb_unanchor_urb(struct urb *urb)
+{
+ unsigned long flags;
+ struct usb_anchor *anchor;
+
+ if (!urb)
+ return;
+
+ anchor = urb->anchor;
+ if (!anchor)
+ return;
+
+ spin_lock_irqsave(&anchor->lock, flags);
+ if (unlikely(anchor != urb->anchor)) {
+ /* we've lost the race to another thread */
+ spin_unlock_irqrestore(&anchor->lock, flags);
+ return;
+ }
+ urb->anchor = NULL;
+ list_del(&urb->anchor_list);
+ spin_unlock_irqrestore(&anchor->lock, flags);
+ usb_put_urb(urb);
+ if (list_empty(&anchor->urb_list))
+ wake_up(&anchor->wait);
+}
+EXPORT_SYMBOL_GPL(usb_unanchor_urb);
+
/*-------------------------------------------------------------------*/
/**
@@ -478,6 +533,48 @@
spin_unlock_irq(&urb->lock);
}
+/**
+ * usb_kill_anchored_urbs - cancel transfer requests en masse
+ * @anchor: anchor the requests are bound to
+ *
+ * this allows all outstanding URBs to be killed starting
+ * from the back of the queue
+ */
+void usb_kill_anchored_urbs(struct usb_anchor *anchor)
+{
+ struct urb *victim;
+
+ spin_lock_irq(&anchor->lock);
+ while (!list_empty(&anchor->urb_list)) {
+ victim = list_entry(anchor->urb_list.prev, struct urb, anchor_list);
+ /* we must make sure the URB isn't freed before we kill it*/
+ usb_get_urb(victim);
+ spin_unlock_irq(&anchor->lock);
+ /* this will unanchor the URB */
+ usb_kill_urb(victim);
+ usb_put_urb(victim);
+ spin_lock_irq(&anchor->lock);
+ }
+ spin_unlock_irq(&anchor->lock);
+}
+EXPORT_SYMBOL_GPL(usb_kill_anchored_urbs);
+
+/**
+ * usb_wait_anchor_empty_timeout - wait for an anchor to be unused
+ * @anchor: the anchor you want to become unused
+ * @timeout: how long you are willing to wait in milliseconds
+ *
+ * Call this is you want to be sure all an anchor's
+ * URBs have finished
+ */
+int usb_wait_anchor_empty_timeout(struct usb_anchor *anchor,
+ unsigned int timeout)
+{
+ return wait_event_timeout(anchor->wait, list_empty(&anchor->urb_list),
+ msecs_to_jiffies(timeout));
+}
+EXPORT_SYMBOL_GPL(usb_wait_anchor_empty_timeout);
+
EXPORT_SYMBOL(usb_init_urb);
EXPORT_SYMBOL(usb_alloc_urb);
EXPORT_SYMBOL(usb_free_urb);
@@ -485,4 +582,3 @@
EXPORT_SYMBOL(usb_submit_urb);
EXPORT_SYMBOL(usb_unlink_urb);
EXPORT_SYMBOL(usb_kill_urb);
-