2.6.18-rt7: rollover with 32-bit cycles_t

[Kevin Hilman]

On ARM, I'm noticing the 'bug' message from check_critical_timing()
where two calls to get_cycles() are compared and the 2nd is assumed to
be >= the first.

This isn't properly handling the case of rollover which occurs
relatively often with fast hardware clocks and 32-bit cycle counters.

Is this really a bug?  If the get_cycles() can be assumed to run between
0 and (cycles_t)~0, using the right unsigned math could get a proper
delta even in the rollover case.  Is this a safe assumption?

Kevin





-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/