From: Ralf Baechle <ralf@linux-mips.org>
To: Manuel Lauss <manuel.lauss@gmail.com>
Cc: Linux-MIPS <linux-mips@linux-mips.org>
Subject: Re: [PATCH v2] MIPS: Alchemy: fix wait function
Date: Mon, 10 Jun 2013 17:49:44 +0200 [thread overview]
Message-ID: <20130610154944.GB5303@linux-mips.org> (raw)
In-Reply-To: <1369315716-7408-1-git-send-email-manuel.lauss@gmail.com>
On Thu, May 23, 2013 at 03:28:36PM +0200, Manuel Lauss wrote:
> Only an interrupt can wake the core from 'wait', enable interrupts
> locally before executing 'wait'.
>
> Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
> ---
> Ralf made me aware of the race in between enabling interrupts and
> entering wait. While this patch does not eliminate it, it shrinks it
> to 1 instruction. It's not perfect, but lets Alchemy boot until a
> more sophisticated solution (like __r4k_wait) can be implemented
> without having to duplicate the interrupt exception handler.
It doesn't shrink it - interrupts will be pending from the time they
were disabled to the point where they get re-enabled. That can be quite
a few cycles and so the likelyhood for hitting the race is not that low.
Ralf
next prev parent reply other threads:[~2013-06-10 15:49 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-23 13:28 [PATCH v2] MIPS: Alchemy: fix wait function Manuel Lauss
2013-06-08 18:18 ` Maciej W. Rozycki
2013-06-08 20:15 ` Manuel Lauss
2013-06-10 15:49 ` Ralf Baechle [this message]
2013-06-10 18:45 ` Maciej W. Rozycki
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