From: Michael Ellerman <michael@ellerman•id.au>
To: Jeremy Kerr <jk@ozlabs•org>
Cc: linuxppc-dev@ozlabs•org
Subject: Re: [PATCH] powerpc: Add write barrier before enabling DTL flags
Date: Tue, 24 Mar 2009 16:53:26 +1100 [thread overview]
Message-ID: <1237874006.6478.284.camel@localhost> (raw)
In-Reply-To: <1237863308.620048.912148989400.1.gpush@pingu>
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On Tue, 2009-03-24 at 13:55 +1100, Jeremy Kerr wrote:
> Currently, we don't enforce any ordering for updates to the lppaca
> when enabling dtl logging, so we may end up enabling logging before the
> index fields have been established.
>
> This change adds a smp_wmb() before doing the actual enable.
>
> Signed-off-by: Jeremy Kerr <jk@ozlabs•org>
>
> ---
> arch/powerpc/platforms/pseries/dtl.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/arch/powerpc/platforms/pseries/dtl.c b/arch/powerpc/platforms/pseries/dtl.c
> index dc9b0f8..fafcaa0 100644
> --- a/arch/powerpc/platforms/pseries/dtl.c
> +++ b/arch/powerpc/platforms/pseries/dtl.c
> @@ -107,6 +107,10 @@ static int dtl_enable(struct dtl *dtl)
> /* set our initial buffer indices */
> dtl->last_idx = lppaca[dtl->cpu].dtl_idx = 0;
>
> + /* ensure that our updates to the lppaca fields have occurred before
> + * we actually enable the logging */
> + smp_wmb();
Wouldn't this still be a problem on a UP kernel?
cheers
--
Michael Ellerman
OzLabs, IBM Australia Development Lab
wwweb: http://michael.ellerman.id.au
phone: +61 2 6212 1183 (tie line 70 21183)
We do not inherit the earth from our ancestors,
we borrow it from our children. - S.M.A.R.T Person
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next prev parent reply other threads:[~2009-03-24 5:53 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <<1236830152.729279.468331899806.3.gpush@pingu>
2009-03-24 2:40 ` [PATCH v2] powerpc: Add virtual processor dispatch trace log Jeremy Kerr
2009-03-24 2:55 ` [PATCH] powerpc: Add write barrier before enabling DTL flags Jeremy Kerr
2009-03-24 5:53 ` Michael Ellerman [this message]
2009-03-24 5:59 ` Jeremy Kerr
2009-03-25 0:44 ` Michael Ellerman
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