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Date: Tue, 6 Jul 2004 01:08:42 -0700
From: Kris Kennaway <kris@obsecurity.org>
To: Tim Robbins <tjr@freebsd.org>
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cc: freebsd-stable@freebsd.org
cc: ngl <ngl@ur.ru>
Subject: Re: Shared/exclusive (rw) locks
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On Tue, Jul 06, 2004 at 05:17:32PM +1000, Tim Robbins wrote:
> On Tue, Jul 06, 2004 at 12:45:27PM +0600, ngl wrote:
> > That means, freebsd stable has no spin rwlocks ?
>=20
> Right. Reader-writer spinlocks would not be very useful in FreeBSD 4; bec=
ause
> only one thread can be running in the kernel at once, the only opportunity
> you'd have to share reader locks would be if you slept while holding a
> spinlock, which is a bad idea (and not permitted by FreeBSD 5 or Linux).
> If you want -rwlocks, you'll have to use lockmgr() (which is a sleep lock=
).

i.e. perhaps you really want to be using FreeBSD 5.

Kris

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