USB: see if URB comes from a completion handler
Now that URBs can be completed inside tasklets, we need a way of
determining whether a completion handler for a given endpoint is
currently running. Otherwise it's not possible to maintain the API
guarantee about keeping isochronous streams synchronous when an
underrun occurs.
This patch adds a field and a routine to check whether a completion
handler for a periodic endpoint is running. At the moment no
analogous routine appears to be necessary for async endpoints, but one
can always be added.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h
index 75efc45..8c86513 100644
--- a/include/linux/usb/hcd.h
+++ b/include/linux/usb/hcd.h
@@ -73,6 +73,7 @@
spinlock_t lock;
struct list_head head;
struct tasklet_struct bh;
+ struct usb_host_endpoint *completing_ep;
};
struct usb_hcd {
@@ -378,6 +379,12 @@
return hcd->driver->flags & HCD_BH;
}
+static inline bool hcd_periodic_completion_in_progress(struct usb_hcd *hcd,
+ struct usb_host_endpoint *ep)
+{
+ return hcd->high_prio_bh.completing_ep == ep;
+}
+
extern int usb_hcd_link_urb_to_ep(struct usb_hcd *hcd, struct urb *urb);
extern int usb_hcd_check_unlink_urb(struct usb_hcd *hcd, struct urb *urb,
int status);