USB: keep count of unsuspended children

This patch (as818b) simplifies autosuspend processing by keeping track
of the number of unsuspended children of each USB hub.  This will
permit us to avoid a good deal of unnecessary work all the time; we
will no longer have to create a bunch of workqueue entries to carry
out autosuspend requests, only to have them fail because one of the
hub's children isn't suspended.

The basic idea is simple.  There already is a usage counter in the
usb_device structure for preventing autosuspends.  The patch just
increments that counter for every unsuspended child.  There's only one
tricky part: When a device disconnects we need to remember whether it
was suspended at the time (leave the counter alone) or not (decrement
the counter).

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/usb.h b/include/linux/usb.h
index 5634a2d91ec0..0cd73edeef13 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -362,6 +362,7 @@ struct usb_device {
         u8 portnum;                     /* Parent port number (origin 1) */
         u8 level;                       /* Number of USB hub ancestors */
 
+        unsigned discon_suspended:1;    /* Disconnected while suspended */
         unsigned have_langid:1;         /* whether string_langid is valid */
         int string_langid;              /* language ID for strings */