Date: Wed, 30 Aug 2000 17:44:15 -0400 (EDT) From: Bosko Milekic <bmilekic@dsuper.net> To: David Malone <dwmalone@maths.tcd.ie> Cc: freebsd-net@FreeBSD.ORG Subject: Re: Proposal to clarify mbuf handling rules Message-ID: <Pine.BSF.4.21.0008301739290.10819-100000@jehovah.technokratis.com> In-Reply-To: <200008301953.aa98962@salmon.maths.tcd.ie>
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On Wed, 30 Aug 2000, David Malone wrote: > Personally, I'd go for the simplest option, to just add a M_RDONLY > flag to the m_flags and use the three condition check for writability. > (That way we can even make normal mbuf read only if we want to - > not that that is necessarily an advantage ;-) > > I guess we could impliment it either way and use macros so it is easy > to change later. > > David. But how would you take care of removing a M_RDONLY flag for an mbuf referring to certain external storage where that one mbuf is not the only mbuf referring to it? i.e. you would have to remove M_RDONLY from all the mbufs referring to the same ext_buf, and this is impossible (and undesired, actually, as it would involve big overhead as a result of giant locks). Or, if that doesn't matter, because you'll be using the three condition check for safe-writability testing, then why do we need the M_RDONLY flag in the first place? Cheers, Bosko Milekic bmilekic@technokratis.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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