On Wed, Feb 7, 2018 at 2:55 AM, Taylor R Campbell <campbell+netbsd-tech-k...@mumble.net> wrote: >> Date: Tue, 6 Feb 2018 19:06:33 +0900 >> From: Ryota Ozaki <ozak...@netbsd.org> >> >> Is there any reason that rw_lock_held checks if it's held >> by *someone*, not by curlwp? It's confusable and most (or all?) >> users of the API seem to expect the latter (held by curlwp). > > Wild guesses: > > (a) because it seemed fast to just test (owner & RW_THREAD) != 0, or > (b) because Solaris did it. > >> So I think we should do either: >> (1) fix rw_lock_held, or >> - probably it would be rw_read_held() || rw_write_held() >> (2) fix users of rw_lock_held. >> - it also would replace rw_lock_held with >> rw_read_held() || rw_write_held() >> >> I prefer (1) because I think there is no user of the current >> behavior that is difficult to use for users (it may be useful >> as an internal utility function though). > > I like (1) too, but check for Solaris compatibility? It is hard to > imagine that there are correct uses of the current semantics that are > not also correct uses of (1).
https://docs.oracle.com/cd/E36784_01/html/E36886/rwlock-9f.html They seem to have only rw_read_locked that is compatible to our rw_read_held. ozaki-r
