Fix geom build with clang 17 and KTR enabled

[dim]

Summary

When building a kernel with clang 17 and KTR enabled, such as with the
LINT configurations, a -Werror warning is emitted:

sys/geom/geom_io.c:145:31: error: use of logical '&&' with constant operand [-Werror,-Wconstant-logical-operand]
  145 |         if ((KTR_COMPILE & KTR_GEOM) && (ktr_mask & KTR_GEOM)) {
      |             ~~~~~~~~~~~~~~~~~~~~~~~~ ^
sys/geom/geom_io.c:145:31: note: use '&' for a bitwise operation
  145 |         if ((KTR_COMPILE & KTR_GEOM) && (ktr_mask & KTR_GEOM)) {
      |                                      ^~
      |                                      &
sys/geom/geom_io.c:145:31: note: remove constant to silence this warning

Since the KTR_xxx constants and the ktr_mask variable are all intended
as bitmasks, use '&' instead.

[mjg]

is this the only occurence of this "error" in the tree?

this either should not be a warning altogether or the compile should ship a way to indicate "yes, this is what was meant".

[dim]

In D41823#953284, @mjg wrote:

is this the only occurence of this "error" in the tree?

this either should not be a warning altogether or the compile should ship a way to indicate "yes, this is what was meant".

Yep, of course you can suppress the warning. But I think it makes sense to warn about mixing logical and bitwise operators. You could also write (KTR_COMPILE & KTR_GEOM) != 0 && (ktr_mask & KTR_GEOM) != 0) but that is effectively the same.

[imp]

Maybe use == instead of & here. And maybe make is a macro?

So (a & b) == (c & b) or

A & b & c != 0

Since a & c & b & c == a & b & c

Which makes sense: if the compile enabled geom tr is there and we have it enabled at run time.

I suggested a macro/inline because I think this crosses the line from trivial check, which we inline directly to more tricky and difficult to get right, which we abstract out.

[dim]

Replace multiple expressions with one macro, and use logical operands in
that macro.

[emaste]

if we're going to make a change like this any reason not to go all the way and just make it a static inline bool?

[dim]

In D41823#953876, @emaste wrote:

if we're going to make a change like this any reason not to go all the way and just make it a static inline bool?

A function, you mean? Or a variable? (Since ktr_mask is already a variable.)

[jhb]

I really think the better fix for this is to rework the CTRSTACK wrapper macro to include the call to stack_save() and for it to incorporate the compile and runtime check. It would make this geom code quite a bit cleaner.

sys/geom/geom_io.c

72

The comparisons of != 0 jointed with && is the right expression IMO.

[jhb]

This is fine for now though.