Date: Sat, 22 Mar 2008 13:57:38 +0000 (GMT) From: Robert Watson <rwatson@FreeBSD.org> To: Ruslan Ermilov <ru@FreeBSD.org> Cc: arch@FreeBSD.org Subject: Re: Disposal of a misleading M_TRYWAIT Message-ID: <20080322135637.Y6961@fledge.watson.org> In-Reply-To: <20080322105145.GA41672@team.vega.ru> References: <20080322105145.GA41672@team.vega.ru>
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On Sat, 22 Mar 2008, Ruslan Ermilov wrote: > I'd like to remove the misleading uses of M_TRYWAIT throughout the tree and > clean up some dead code that assumes its original behavior (that it could > return NULL). > > Since the advent of MBUMA in FreeBSD (whatever), M_TRYWAIT has meant > M_WAITOK. (The reason for M_TRYWAIT itself was that an original mbuf's > M_WAIT could return NULL.) > > There is little or no sign that this will change, and there are lots of > consumers that already pass M_WAITOK to mbuf allocator routines and rely on > its invariants, so support for the concept of M_TRYWAIT has rotted and would > have to be re-written anyway if reintroduced. > > http://people.freebsd.org/~ru/patches/M_TRYWAIT.patch This seems reasonable to me for exactly the reasons you stte. We might simultaneously want to complete the M_DONTWAIT -> M_NOWAIT conversion. And you can then remove the XXX comment in mbuf.h about phasing out M_TRYWAIT and M_DONTWAIT. :-) Robert N M Watson Computer Laboratory University of Cambridge
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