From: Gabriel Paubert <paubert@iram.es>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: ppc-dev <linuxppc-dev@ozlabs.org>,
Dave Liu <r63238@freescale.com>,
Paul Mackerras <paulus@samba.org>,
Kumar Gala <galak@gate.crashing.org>
Subject: Re: fsl booke MM vs. SMP questions
Date: Tue, 22 May 2007 12:02:12 +0200 [thread overview]
Message-ID: <20070522100212.GA13225@iram.es> (raw)
In-Reply-To: <1179825278.32247.827.camel@localhost.localdomain>
On Tue, May 22, 2007 at 07:14:38PM +1000, Benjamin Herrenschmidt wrote:
> > Why do you want to clear the reservation here?
> >
> > Coming out of some code path with the reservation still held
> > can only affect buggy code (someone doing st[dw]cx. before
> > l[dw]arx) AFAIK.
>
> And buggy CPUs :-)
>
> Seriously, lots of CPU implementations don't test the address for local
> lwarx stwcx. so if your kernel code "replaces" a reservation with
> another that is left set, the userland stwcx. might well succeed which
> is bogus.
>
Well, there should always be an stwcx. to clear reservation before
any interrupt return. Otherwise you'll be able to cause hard to
reproduce bugs in the interrupted code.
Checking or not that the reservation address matches the stwcx.
is irrelevant.
Gabriel
next prev parent reply other threads:[~2007-05-22 10:02 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-21 7:06 fsl booke MM vs. SMP questions Benjamin Herrenschmidt
[not found] ` <1179741447.3660.7.camel@localhost.localdomain>
[not found] ` <1179742083.32247.689.camel@localhost.localdomain>
2007-05-21 11:37 ` Dave Liu
2007-05-21 22:07 ` Benjamin Herrenschmidt
2007-05-22 3:09 ` Benjamin Herrenschmidt
2007-05-22 10:56 ` Dave Liu
2007-05-22 22:42 ` Benjamin Herrenschmidt
2007-05-23 2:38 ` Dave Liu
2007-05-23 3:08 ` Benjamin Herrenschmidt
2007-05-28 9:05 ` Liu Dave-r63238
2007-05-28 9:24 ` Benjamin Herrenschmidt
2007-05-28 9:37 ` Liu Dave-r63238
2007-05-28 10:00 ` Benjamin Herrenschmidt
2007-05-28 10:23 ` Gabriel Paubert
2007-05-28 10:28 ` Benjamin Herrenschmidt
2007-05-22 8:46 ` Gabriel Paubert
2007-05-22 9:14 ` Benjamin Herrenschmidt
2007-05-22 10:02 ` Gabriel Paubert [this message]
2007-05-22 10:05 ` Benjamin Herrenschmidt
2007-05-23 9:12 ` Gabriel Paubert
2007-05-22 3:03 ` Kumar Gala
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