Date: Fri, 24 Jul 1998 09:30:14 -0400 (EDT) From: Robert Watson <robert@cyrus.watson.org> To: wjw@IAEhv.nl Cc: Doug Rabson <dfr@nlsystems.com>, hackers@FreeBSD.ORG Subject: Re: SYSCTL ....... Message-ID: <Pine.BSF.3.96.980724092639.22685C-100000@fledge.watson.org> In-Reply-To: <199807241032.MAA19151@surf.IAE.nl>
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On Fri, 24 Jul 1998, Willem Jan Withagen wrote: > You ( Doug Rabson ) write: > => > Intresting point. > => > I haven't thought about this point. I considered that once submitted OID's > => > are there for ever. But evaporating LKM's would case some access trouble. > => > => I think that coping well with loading/unloading modules is a requirement > => since supporting loadable drivers (and other components) is a goal we > => should be working towards. > > It could have some influence on the data-structures if deleteing nodes is > a frequent operation. The alternative would be to invalidate te content > pointers. > It also puts a serious commitment by the LKM-builder. He needs to make shure > he unregisters everything he has registered. Which could be more than he/she > bargained for. LKM writers should not register sysctl nodes unless they are willing to delete them afterwards. It is the same as any kernel hook -- if an lkm calls at_fork(), they are morally obligated to call rm_at_fork() when they unload :). Otherwise things go down the tubes pretty quickly. However, the interface should make it extremely easy for the lkm writer to register/unregister without excessive overhead. Also, to detect duplicate registrations, etc. I don not think deleting would be a frequent (read: performance-intensive) activity, as relinking stuff in your running kernel is bound to be slow anyway. Unless we plan to providing routing information or something through a dynamic sysctl mechanism :). Robert N Watson Carnegie Mellon University http://www.cmu.edu/ TIS Labs at Network Associates, Inc. http://www.tis.com/ SafePort Network Services http://www.safeport.com/ robert@fledge.watson.org http://www.watson.org/~robert/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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