Date: Mon, 12 Nov 2001 15:04:27 -0800 (PST)
From: Julian Elischer <julian@elischer.org>
To: Matthew Dillon <dillon@apollo.backplane.com>
Cc: Terry Lambert <tlambert2@mindspring.com>, Robert Watson <rwatson@FreeBSD.ORG>, freebsd-arch@FreeBSD.ORG
Subject: Re: cur{thread/proc}, or not.
Message-ID: <Pine.BSF.4.21.0111121503200.94926-100000@InterJet.elischer.org>
In-Reply-To: <200111122254.fACMsNd06845@apollo.backplane.com>
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On Mon, 12 Nov 2001, Matthew Dillon wrote: > :The point is that if the credentials are granted, then a > :change in credential is not a change of the credential itself, > :but is instead a copy-on-write proposition. In other words, > :credentials, once granted, are priviledge stable. > : > :If this is the case, then they are written when they are > :instanced, cloned before they are modified (indeed, it seems > :that the clone/modify operation must be made atomic), and > :thus are never written once instanced -- only destroyed on > :the 1->0 reference transition. > : > :If so, then no locking is required, since the LCK CMPXCHG can > :be utilized to do atomic increment and decrement on the > :reference counting, without needing locks. > :... > : > :-- Terry > > Yes, I believe this is how credentials work. I looked at > the code about 6 months ago. We should not have to do any > locking of the credential stuff, only simple mutexing > around the ref counter. That is how it should work > is how I believe it currently works. This is not how they work, but rather how they WILL work given that the commit happens soon (maybe it was already done last week and I missed it...) > > -Matt > Matthew Dillon > <dillon@backplane.com> > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-arch" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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