On Mon, 16 Jul 2007, Dave Jones wrote:
> > > in usb_autopm_do_device()
> > > I'm suspecting logic is underflowing here causing this.
> >
> > Yes, that's what it means. I'm puzzled as to how this could occur; let
> > me try some tests. What types of devices give rise to these warnings?
>
> On the machine I tried it on, there's nothing really exotic..
> lsusb shows..
> Bus 005 Device 054: ID 0781:5150 SanDisk Corp. SDCZ2 Cruzer Mini Flash Drive
> (thin)
> Bus 005 Device 002: ID 050d:0234 Belkin Components F5U234 USB 2.0 4-Port Hub
> Bus 005 Device 001: ID 0000:0000
> Bus 004 Device 003: ID 0aec:3050 Neodio Technologies Corp. ND3050 8-in-1 Card
> Reader
> Bus 004 Device 001: ID 0000:0000
> Bus 003 Device 001: ID 0000:0000
> Bus 002 Device 004: ID 04a9:1097 Canon, Inc.
> Bus 002 Device 003: ID 045e:0053 Microsoft Corp.
> Bus 002 Device 001: ID 0000:0000
> Bus 001 Device 001: ID 0000:0000
>
> so, usb memory stick, hub, card reader, printer, mouse.
>
> The 28 warnings in my dmesg are all preceded by..
> usb 5-1.4: new high speed USB device using ehci_hcd and address 51
> usb 5-1.4: configuration #1 chosen from 1 choice
>
> I'm not sure how that 5-1.4 relates to the above map.
>
> oh, there's one other case, where it prints the same thing for usb 4-2:
All right, it turns out there really is a minor bug that shows up only
with the autosuspend delay set to 0. The patch below fixes it (should
you happen to care).
Alan Stern
Index: 2.6.22/drivers/usb/core/hub.c
===================================================================
--- 2.6.22.orig/drivers/usb/core/hub.c
+++ 2.6.22/drivers/usb/core/hub.c
@@ -1388,6 +1388,10 @@ int usb_new_device(struct usb_device *ud
udev->dev.devt = MKDEV(USB_DEVICE_MAJOR,
(((udev->bus->busnum-1) * 128) + (udev->devnum-1)));
+ /* Increment the parent's count of unsuspended children */
+ if (udev->parent)
+ usb_autoresume_device(udev->parent);
+
/* Register the device. The device driver is responsible
* for adding the device files to sysfs and for configuring
* the device.
@@ -1395,13 +1399,11 @@ int usb_new_device(struct usb_device *ud
err = device_add(&udev->dev);
if (err) {
dev_err(&udev->dev, "can't device_add, error %d\n", err);
+ if (udev->parent)
+ usb_autosuspend_device(udev->parent);
goto fail;
}
- /* Increment the parent's count of unsuspended children */
- if (udev->parent)
- usb_autoresume_device(udev->parent);
-
exit:
return err;
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