Taylor R Campbell <campbell+netbsd-source-change...@mumble.net> wrote: > Date: Wed, 12 Mar 2014 16:16:32 +0200 > From: Jukka Ruohonen <jruoho...@iki.fi> > > On Wed, Mar 12, 2014 at 09:39:23AM +0000, Juergen Hannken-Illjes wrote: > > Restructure layer_lock() to always lock before testing for dead node. > > Use ISSET() to test flags, add assertions. > > As I wrote in the manual page, I'd rather see ISSET(3) et. al. > disappear, i.e. these obscure rather than clarify... > > I disagree. Phrases like `(vp->v_iflag & (VI_XLOCK | VI_CLEAN)) == 0' > make my head's parser stumble -- there are just enough complements to > juggle that it overwhelms my brain registers for the fast path. I'd > rather read `!ISSET(vp->v_iflag, (VI_XLOCK | VI_CLEAN))'.
I disagree. For kernel developers, that kind of bitwise arithmetics and masking ought to be intuitive. If there is more logic and it gets long, then separate it: const bool foobar = (mask & (FOO | BAR)) == 0; const bool baz = (mask & BAZ) != 0; if (foobar && baz) ... ISSET() is somewhat okay (although I do not use it), but I particularly dislike __BIT() as I forget whether the 1st bit is n = 0 or whether this API tries to be fancy and it is n = 1. 1U << n is just straigtforward. -- Mindaugas
