Date: Fri, 30 Jun 2006 14:57:37 -0400 From: John Baldwin <jhb@freebsd.org> To: Warner Losh <imp@bsdimp.com> Cc: sam@errno.com, src-committers@freebsd.org, cvs-all@freebsd.org, cvs-src@freebsd.org Subject: Re: cvs commit: src/sys/kern kern_module.c Message-ID: <200606301457.38376.jhb@freebsd.org> In-Reply-To: <20060629.235856.74667657.imp@bsdimp.com> References: <200606261834.k5QIYkEF005337@repoman.freebsd.org> <200606270848.29250.jhb@freebsd.org> <20060629.235856.74667657.imp@bsdimp.com>
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On Friday 30 June 2006 01:58, Warner Losh wrote: > From: John Baldwin <jhb@freebsd.org> > Subject: Re: cvs commit: src/sys/kern kern_module.c > Date: Tue, 27 Jun 2006 08:48:28 -0400 > > > On Monday 26 June 2006 19:41, Sam Leffler wrote: > > > John Baldwin wrote: > > > > jhb 2006-06-26 18:34:45 UTC > > > > > > > > FreeBSD src repository > > > > > > > > Modified files: > > > > sys/kern kern_module.c > > > > Log: > > > > Address a problem I missed in removing Giant from the kernel linker. Not > > > > all of the module event handlers are MP safe yet, so always acquire Giant > > > > for now when invoking module event handlers. Eventually we can add an > > > > MPSAFE flag or some such and add appropriate locking to all module event > > > > handlers. > > > > > > I suggest we should be marking things !MPSAFE rather than MPSAFE. > > > > > > Sam > > > > I would prefer that as well but that would require an exhaustive search of > > all existing module event handlers to determine MPSAFE-ness up front. With > > the mark as MPSAFE method (such as we've used for syscalls) we can mark things > > MPSAFE (and/or add locking to make them MPSAFE) while doing the exhaustive > > search and eventually when all are MPSAFE we can remove the flag (which I'm > > in the process of doing now with the syscall flag) all the while having a > > functioning system. > > We have three cases right now: > > (1) Unknown > (2) MPSAFE > (3) NEEDS GIANT > > All the unknown ones need giant right now, or at least that's a > reasonable guess. Certainly all the device driver ones do since you > need giant to do certain device tree activities. > > Short of introducing a new API, I'm unsure how we'd be able to > effectively and safely do NEEDS_GIANT marking in the interrum. DECLARE_MODULE_MPSAFE() or some such is how one would do it, but for now they are all in the (1) category. -- John Baldwin
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