Date: Tue, 24 Apr 2001 13:47:17 -0400 (EDT) From: "Andrew R. Reiter" <arr@watson.org> To: Robert Watson <rwatson@FreeBSD.ORG> Cc: John Baldwin <jhb@FreeBSD.ORG>, smp@FreeBSD.ORG Subject: RE: sysctl's and mutexes Message-ID: <Pine.NEB.3.96L.1010424134320.18652A-100000@fledge.watson.org> In-Reply-To: <Pine.NEB.3.96L.1010424131753.9817D-100000@fledge.watson.org>
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On Tue, 24 Apr 2001, Robert Watson wrote: > On Tue, 24 Apr 2001, John Baldwin wrote: > > > > int jail_set_hostname_allowed = 1; > > > SYSCTL_INT(_jail, OID_AUTO, set_hostname_allowed, CTLFLAG_RW|CTLFLAG_MTX, > > > &jail_set_hostname_allowed, &jail_set_hostname_allowed_mtx, 0, > > > "Processes in jail can set their hostnames"); > > > > It might very well be desirable to add a new parameter for each sysctl > > that is a pointer to a mutex. However, an appropriate SYSINIT() or some > > such during startup needs to initialize that mutex before that sysctl is > > used. If need be, we can also add a flag to determine if the sysctl > > should initialize the mutex itself or not. Ideally then, we would > > create a new SYSINIT on the fly to initialize the mutex in question. I > > think though, that requiring explicit initialization of each mutex > > shouldn't be too hard. > > I don't have strong feelings on the exact nature of how mutices are bound > to sysctl's, as long as it's possible to do the following: > > 1) It should be possible to use an existing initialized mutex, especially > with regards to dynamically allocated sysctl's. > > 2) It should be possible for several sysctl's to share the same mutex. As in being able to say that for (and this might be a bad example) kern.timecounter.* mibs, could all share a mutex which is really "bound" to kern.timecounter in genera. Or do you mean just more generically the idea that multiple sysctl's can share a mutex and who/what shares a mutex is something to be decided? > > Robert N M Watson FreeBSD Core Team, TrustedBSD Project > robert@fledge.watson.org NAI Labs, Safeport Network Services > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-smp" in the body of the message > *-------------................................................. | Andrew R. Reiter | arr@fledge.watson.org | "It requires a very unusual mind | to undertake the analysis of the obvious" -- A.N. Whitehead To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message
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