Hi,
On 2026-04-12 14:20:31 -0400, Tom Lane wrote:
> Lukas Fittl <lukas@fittl.com> writes:
> > FWIW, for archive's sake, drongo is green again now, thanks to commit
> > 7fc36c5db550 (Avoid CPUID 0x15/0x16 for Hypervisor TSC frequency).
>
> drongo may be happy, but Coverity is not:
>
> 166 uint64 loop_count;
> 167
> 168 loop_count = test_timing(test_duration, TIMING_CLOCK_SOURCE_SYSTEM, false);
> >>> CID 1691465: Incorrect expression (DIVIDE_BY_ZERO)
> >>> In function call "output", division by expression "loop_count" which may be zero has undefined behavior.
> 169 output(loop_count);
>
> AFAICS it's correct to complain. test_timing() visibly can return zero,
> but of the three places where test_timing() is followed by output()
> only one has a defense against that.
I think it should be unreachable as-is (but we should fix it anyway): If the
system clock source doesn't work, we have much bigger issues. If rdtscp works,
rdtsc should better work as well...
Maybe it's enough to add an Assert() to clarify this? But I guess just
printing a message in that unreachable case would also work.
Greetings,
Andres Freund
