Date: Fri, 08 Sep 2000 16:33:01 -0700 From: Jake Burkholder <jburkhol@home.com> To: Daniel Eischen <eischen@vigrid.com> Cc: Alfred Perlstein <bright@wintelcom.net>, smp@FreeBSD.ORG Subject: Re: SMPng: catching signals and mutexes. Message-ID: <20000908233301.D27EBBA6D@io.yi.org> In-Reply-To: Message from Daniel Eischen <eischen@vigrid.com> of "Fri, 08 Sep 2000 15:48:18 EDT." <Pine.SUN.3.91.1000908154525.10025A@pcnet1.pcnet.com>
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> On Fri, 8 Sep 2000, Alfred Perlstein wrote:
> > There seems to be no way to specify that a signal is to interrupt
> > a wait on a mutex, I'm wondering if we should make it possible to
> > do so.
>
> [...]
>
> > I'm not sure I like this at all, shouldn't there be an
> > mtx_enter with some option to return an error if a signal
> > arrives?
>
> IMHO, yes. Solaris has cv_wait_sig() for just that.
>
Mutexes are meant to serve a different purpose than tsleep or
condition variables.
The next thing in line is to add a mutex argument to tsleep,
which will be atomicly released and re-acquired upon resume.
The code in question might then look like:
mtx_enter(&sb->sb_mtx, MTX_DEF);
while (sb->sb_flags & SB_LOCK) {
sb->sb_flags |= SB_WANT;
error = tsleep((caddr_t)&sb->sb_flags, sb->sb_mtx,
(sb->sb_flags & SB_NOINTR) ? PSOCK : PSOCK|PCATCH,
"sblock", 0);
if (error) {
mtx_exit(sb->sb_mtx, MTX_DEF);
return (error);
}
}
sb->sb_flags |= SB_LOCK;
mtx_exit(sb->sb_mtx, MTX_DEF);
Jake
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