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>
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 46df5e6..e46d38b 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -1039,6 +1039,8 @@
if (udev->children[i])
recursively_mark_NOTATTACHED(udev->children[i]);
}
+ if (udev->state == USB_STATE_SUSPENDED)
+ udev->discon_suspended = 1;
udev->state = USB_STATE_NOTATTACHED;
}
@@ -1228,6 +1230,14 @@
*pdev = NULL;
spin_unlock_irq(&device_state_lock);
+ /* Decrement the parent's count of unsuspended children */
+ if (udev->parent) {
+ usb_pm_lock(udev);
+ if (!udev->discon_suspended)
+ usb_autosuspend_device(udev->parent, 1);
+ usb_pm_unlock(udev);
+ }
+
put_device(&udev->dev);
}
@@ -1356,6 +1366,10 @@
goto fail;
}
+ /* Increment the parent's count of unsuspended children */
+ if (udev->parent)
+ usb_autoresume_device(udev->parent, 1);
+
exit:
module_put(THIS_MODULE);
return err;