The pointer from a xhci usb virt device to its root hub port
(vdev->rhub_port) is set later when device is addressed, not while
vdev is allocated.

Tracepoints dereferenced this rhub_port pointer when freeing the virt
device, which causes null pointer dereference if tracing is enabled
and device is freed before addressed.

This can happen if tracing is enabled and xhci driver is unloaded before
a device is fully enumerated, or initial enumeration fails and device
is reset and freed before retry.

Don't dereference the rhub_port or show port numbers when tracing
xhci_free_virt_device(). This info is not very useful anyway.

Print the more useful slot id instead

Fixes: 06790c19 ("xhci: replace real & fake port with pointer to root hub port")
Reported-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Closes: https://lore.kernel.org/linux-usb/20240402005007.klv2ij727fkz7rpd@synopsys.com/Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20240404121106.2842417-3-mathias.nyman@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>