LinuxKPI: implement get_random_u32_inclusive()

[bz]

Summary

Attempt of an implementation of get_random_u32_inclusive().
This is needed by an update for wireless drivers.

Sponsored by: The FreeBSD Foundation
MFC after: 10 days

[emaste]

sys/compat/linuxkpi/common/include/linux/random.h

62

low and top seem like an odd pair - I'd think low and high, bottom and top, or floor and ceil.

[bz]

Change function argument names to floor/ceil as suggested by @emaste.

[bz]

Anyone?

[• hselasky]

sys/compat/linuxkpi/common/include/linux/random.h

70

Is there a reason for the while loop? Is zero not valid for "x >> 32" ?

[emaste]

See also https://arxiv.org/pdf/1805.10941.pdf

[• hselasky]

Maybe add:
MPASS(ceil >= floor);

Maybe add a comment showing the reference to the .PDF document explaining the formula ...

What do you think?

sys/compat/linuxkpi/common/include/linux/random.h

70

@emaste : Thanks for the link!

[bz]

Address review comments.

@emaste, do you think this is okay now?