On Tue, 13 Jul 2004, Jesse Stockall wrote:
> Log is attached
>
> > Did lsusb hang immediately after booting? What drivers and USB
> > devices had been loaded?
> >
>
> System boots. X is started. Login on VT1. Run lsusb. See attachment for
> modules loaded. Mouse and on-board hub are only devices.
>
> > What would happen if instead of running lsusb you tried to cat
> > /proc/bus/usb/devices?
> >
>
> Hangs, same as lsusb. The following line appears in dmesg after I ran
> 'cat /proc/bus/usb/devices'
>
> usb_lock_device: udev=f7fd2800 count=fffefffe
>
> > Was some earlier process (like a modprobe) already hung when these other
> > problems occurred?
> >
>
> No, all modules are loaded, and hotplug / udev have finished. Mouse
> works fine in X
>
> Jesse
A very informative and detailed response, thank you.
The problem shows up clearly in your "dmesg" file; something is calling
usb_unlock_device() without calling usb_lock_device() first.
Unfortunately the diagnostic patch didn't include a dump_stack() call in
usb_unlock_device(), so I can't tell who the guilty party is.
Here's a shorter patch for you to try. It ought to pinpoint the culprit.
This is probably some stupid mistake on my part that will end up being
obvious, but I just can't see where it is...
Alan Stern
===== drivers/usb/core/usb.c 1.281 vs edited =====
--- 1.281/drivers/usb/core/usb.c Wed Jun 30 09:44:26 2004
+++ edited/drivers/usb/core/usb.c Wed Jul 7 14:04:02 2004
@@ -891,6 +854,9 @@
*/
void usb_lock_device(struct usb_device *udev)
{
+ printk(KERN_INFO "%s: udev=%p count=%lx\n", __FUNCTION__, udev,
+ usb_all_devices_rwsem.count);
+ dump_stack();
down_read(&usb_all_devices_rwsem);
down(&udev->serialize);
}
@@ -968,6 +934,9 @@
*/
void usb_unlock_device(struct usb_device *udev)
{
+ printk(KERN_INFO "%s: udev=%p count=%lx\n", __FUNCTION__, udev,
+ usb_all_devices_rwsem.count);
+ dump_stack();
up(&udev->serialize);
up_read(&usb_all_devices_rwsem);
}
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