Re: usb suspend backtraces.

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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