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Commit c7ccde6e authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
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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: default avatarAlan Stern <stern@rowland.harvard.edu>
CC: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 272b98c6

drivers/usb/core/hcd.c

+2 −0
Original line number Diff line number Diff line
@@ -1703,7 +1703,9 @@ static void usb_giveback_urb_bh(unsigned long param) 


		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 */

include/linux/usb/hcd.h

+7 −0
Original line number Diff line number Diff line
@@ -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(struct usb_hcd *hcd) 
	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);