uma: UMA_ALIGN_CACHE: Resolve the proper value at use point

[olce]

Summary

Having a special value of -1 that is resolved internally to
'uma_align_cache' provides no significant advantages and prevents
changing that variable to an unsigned type, which is natural for an
alignment mask. So suppress it and replace its use with a call to
uma_get_align_mask(). The small overhead of the added function call is
irrelevant since UMA_ALIGN_CACHE is only used when creating new zones,
which is not performance critical.

MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation

[kib]

sys/vm/uma_core.c

3259

Perhaps add asserts checking that mask is reasonable. I wonder if there are cases where -1 was passed by some reason.

As I understand, the check should be that align is > 0 and is some power of two - 1.

[olce]

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[olce]

sys/vm/uma_core.c

3259

Already done in D42263. The first point, alignment > 0, is automatically true since the mask is switched to unsigned int type in the next patch (see D42262).