"unsigned expression < 0" always false warning

[Bjorn Helgaas <bhelgaas@google.com>]

Can somebody help me resolve the following warning, please?

$ make W=1 drivers/pci/pcie/aer/aerdrv_errprint.o
...
  CC      drivers/pci/pcie/aer/aerdrv_errprint.o
In file included from include/trace/ftrace.h:356:0,
                 from include/trace/define_trace.h:86,
                 from include/trace/events/ras.h:77,
                 from drivers/pci/pcie/aer/aerdrv_errprint.c:27:
include/trace/events/ras.h: In function ‘ftrace_define_fields_aer_event’:
include/trace/events/ras.h:72:1: warning: comparison of unsigned
expression < 0 is always false [-Wtype-limits]

I think it's related to "status" being a u32 below (this is from
include/trace/events/ras.h), but I don't know whether that's incorrect
or how to fix it:

TRACE_EVENT(aer_event,
        TP_PROTO(const char *dev_name,
                 const u32 status,
                 const u8 severity),

        TP_ARGS(dev_name, status, severity),

        TP_STRUCT__entry(
                __string(       dev_name,       dev_name        )
                __field(        u32,            status          )
                __field(        u8,             severity        )
        ),
        ...

Thanks,
  Bjorn