kern_poll: Restore explanatory comment removed in r177374
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Authored by cem on Oct 23 2018, 5:44 PM.

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jeff
peter
markj

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rS340038: kern_poll: Restore explanatory comment removed in r177374

Summary

The comment isn't stale. The check is bogus in the sense that poll(2)
does not require pollfd entries to be unique in fd space, so there is no
reason there cannot be more pollfd entries than open or even allowed
fds. The check is mostly a seatbelt against accidental misuse or
abuse. FD_SETSIZE, while usually unrelated to poll, is used as an
arbitrary floor for systems with very low kern.maxfilesperproc.

No functional change.

Additionally, document this possible EINVAL condition in the poll.2
manual.

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rS FreeBSD src repository - subversion

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cem created this revision.Oct 23 2018, 5:44 PM

Harbormaster completed remote builds in B20365: Diff 49521.Oct 23 2018, 5:44 PM

markj accepted this revision.Oct 24 2018, 2:49 PM

markj added inline comments.

lib/libc/sys/poll.2
242 ↗	(On Diff #49521)	s/and/or/? Why not just, "exceeds the system tunable .Va kern.maxfilesperproc or .Dv FD_SETSIZE."?

This revision is now accepted and ready to land.Oct 24 2018, 2:49 PM

cem marked an inline comment as done.Oct 24 2018, 7:24 PM

cem added inline comments.

lib/libc/sys/poll.2
242 ↗	(On Diff #49521)	The condition is 'and', not or. I'm not sure of the best way to phrase it. I think maxfilesperproc is sort of the primary seatbelt and FD_SETSIZE is a sanity check that maxfilespreproc isn't set super low. I'd be ok reducing it to the simpler sentence: "exceeds the system ... and FD_SETSIZE" if that reads better to you.