Date: Thu, 07 Dec 2000 02:01:33 +0000 From: Brian Somers <brian@Awfulhak.org> To: Julian Elischer <julian@elischer.org> Cc: Brian Somers <brian@Awfulhak.org>, smp@FreeBSD.org, archie@FreeBSD.org, brian@Awfulhak.org Subject: Re: Netgraph and SMP Message-ID: <200012070201.eB721Yt44116@hak.lan.Awfulhak.org> In-Reply-To: Message from Julian Elischer <julian@elischer.org> of "Wed, 06 Dec 2000 06:49:50 PST." <3A2E520E.5E4444BD@elischer.org>
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> >
> > Inside it's own lock (preventing any other dependent modules from
> > appearing), it asks the module if it's ok to unload.
> >
> > This is obviously more tricky than it sounds. We've got to ensure
> > that if any character device entry points have been created
> > (make_dev() etc), we block the relevant entry points so that we can
> > ENODEV if the MOD_UNLOAD works.
>
> but what if the process has already entered the driver?
Then it should hold a lock that fails in the kldload syscall when it
does a mutex_trylock() on it. Again, this is somewhere that a read/
write mutex would be handy. kldunload ends up trying for the write
lock while driver entry points try for the read lock.
--
Brian <brian@Awfulhak.org> <brian@[uk.]FreeBSD.org>
<http://www.Awfulhak.org>; <brian@[uk.]OpenBSD.org>
Don't _EVER_ lose your sense of humour !
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