Split kern_poll() on two counterparts.

[dchagin]

Summary

The kern_poll() operates on clear kernel data, while the kern_poll_ufds()
operates on user supplied pollfd.
Move nfds check to kern_poll_maxfds().

No functional changes, it's for future use in the Linux emulation layer.

[dchagin]

make kern_poll private, kern_poll_ufds - public
use kern_poll_ufds in freebsd32, linux

[dchagin]

export both methods

[kib]

I believe it would be useful to add a comment above each of kern_poll_{u,k}fds, explaining that corresponding function expects from fds pointer.

sys/kern/sys_generic.c

1575

I would make kern_poll_maxfds() returning bool, and then just write

if (!kern_poll_maxfds(nfds))
    return (EINVAL);

[dchagin]

fixed

[dchagin]

I left the previous name for the kern_poll() to not break third-party modules

[kib]

sys/kern/sys_generic.c

1422

I do not see much sense in the second sentence.

[dchagin]

fix comment