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/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index d6a8d23..3a2e82a 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -1703,7 +1703,9 @@
urb = list_entry(local_list.next, struct urb, urb_list);
list_del_init(&urb->urb_list);
+ bh->completing_ep = urb->ep;
__usb_hcd_giveback_urb(urb);
+ bh->completing_ep = NULL;
}
/* check if there are new URBs to giveback */