Re: USBDEVFS_RESET deadlocks USB bus.

[Greg KH <greg@kroah.com>]

On Fri, Jun 04, 2004 at 03:39:11PM -0400, Zephaniah E. Hull wrote:
> Starting at 2.6.7-rc1 or so (that is when we first noticed it) the new
> pilot-link libusb back end started deadlocking the entire USB bus that
> the palm device was on.
> 
> I have finally tracked it down to happening when we make the
> USBDEVFS_RESET ioctl, we never return from it and from that point on the
> bus in question is completely dead, no processing is done, no
> notifications of devices being plugged in or unplugged.
> 
> This is still happening in 2.6.7-rc2-mm1.
> 
> It seems to happen with both the UHCI and OHCI back ends, so it is
> probably above that.
> 
> Given that there were heavy locking changes, I suspect that the case in
> question got screwed up somehow.

This needs to go to the linux-usb-devel list, now CC:

Anyway, can you look at the output of SysRq-T and see where the
processes are hung?

thanks,

greg k-h