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 <st...@rowland.harvard.edu>
CC: Ming Lei <tom.leim...@gmail.com>
---
[as1705]
drivers/usb/core/hcd.c | 2 ++
include/linux/usb/hcd.h | 7 +++++++
2 files changed, 9 insertions(+)
Index: usb-3.11/include/linux/usb/hcd.h
===================================================================
--- usb-3.11.orig/include/linux/usb/hcd.h
+++ usb-3.11/include/linux/usb/hcd.h
@@ -73,6 +73,7 @@ struct giveback_urb_bh {
spinlock_t lock;
struct list_head head;
struct tasklet_struct bh;
+ struct usb_host_endpoint *completing_ep;
};
struct usb_hcd {
@@ -378,6 +379,12 @@ static inline int hcd_giveback_urb_in_bh
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);
Index: usb-3.11/drivers/usb/core/hcd.c
===================================================================
--- usb-3.11.orig/drivers/usb/core/hcd.c
+++ usb-3.11/drivers/usb/core/hcd.c
@@ -1690,7 +1690,9 @@ static void usb_giveback_urb_bh(unsigned
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 */
--
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