Date: Wed, 5 Nov 2003 09:13:59 -0800 From: Sam Leffler <sam@errno.com> To: Hartmut Brandt <harti@FreeBSD.org>, src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/dev/hatm if_hatm.c if_hatmvar.h [MPSAFE network] Message-ID: <200311050913.59097.sam@errno.com> In-Reply-To: <200311051147.hA5BlWiV057262@repoman.freebsd.org> References: <200311051147.hA5BlWiV057262@repoman.freebsd.org>
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On Wednesday 05 November 2003 03:47 am, Hartmut Brandt wrote: > harti 2003/11/05 03:47:32 PST > > FreeBSD src repository > > Modified files: > sys/dev/hatm if_hatm.c if_hatmvar.h > Log: > Make the driver conditionally MPSAFE. MPSAFEty defaults to not-mpsafe > but can be enabled by setting hw.atm.hatmN.mpsafe in the kernel > environment to a non-zero value before loading the driver. When > the problems with network MPSAFEty have been sorted out this will > be removed and the driver will default to MPSAFE. I'm about to commit mods to make debug_mpsafenet globally visible so other parts of the system (to be committed) can use it too. Perhaps your stuff should reference it also? FWIW the problems with the MPSAFE changes I committed were two-fold. Most importantly I'd forgotten that the direct dispatch in the netisr code was left on (I thought Robert had reverted his change). This meant that drivers marked MPSAFE were potentially dispatching directly into the protocol stacks w/o Giant. This obviously caused major problems as there was no interlocking against the top half of the kernel. The second problem is that it turns out that significant bits of IPv4 are not properly locked (contrary to existing claims). The effects of this were less obvious because of the first problem, but both contributed to major instability so rather than try to bandaid the problem I just backed everytihng out to let other major changes (e.g. interrupt routing) settle before trying again. Going forward what I plan to do is commit a set of changes to bring in all the work I've done to "push Giant up" one level (previously I tried to bring things in in stages so each set of changes could get individual exposure). The new code grabs Giant depending on whether each netisr is MPSAFE or not. Then at the next level up Giant is acquired as needed, with this conditional on debug_mpsafenet (sysctl debug.mpsafenet). In the initial commit all the code will go in but with debug_mpsafenet 0. Then I'll need folks that were having problems test with debug_mpsafenet set to 1. Once things look ok I'll change the default to 1. Sam
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