From: Andrew Morton <akpm@digeo.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: davej@codemonkey.org.uk, schlicht@uni-mannheim.de,
torvalds@transmeta.com, hugh@veritas.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH][2.5] fix preempt-issues with smp_call_function()
Date: Wed, 26 Feb 2003 10:47:23 -0800 [thread overview]
Message-ID: <20030226104723.76df4b18.akpm@digeo.com> (raw)
In-Reply-To: <1046266771.8948.1.camel@irongate.swansea.linux.org.uk>
Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
>
> On Wed, 2003-02-26 at 10:28, Andrew Morton wrote:
> > Dave Jones <davej@codemonkey.org.uk> wrote:
> > >
> > > btw, (unrelated) shouldn't smp_call_function be doing magick checks
> > > with cpu_online() ?
> >
> > Looks OK? It sprays the IPI out to all the other CPUs in cpu_online_map,
> > and waits for num_online_cpus()-1 CPUs to answer.
>
> You cannot do that by counting without a lot of care. IPI messages do not have
> guaranteed "once only" semantics. On an error a resend can and has been observed
> to cause a reissue of an IPI on PII/PIII setups
If that resend results in delivery of an actual extra interrupt, the
resent-to CPU can start playing with stuff which used to be on the sender's
stack and the box goes splat.
Didn't sct have a fix for that?
next prev parent reply other threads:[~2003-02-26 18:36 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-02-25 18:08 [PATCH][2.5] fix preempt-issues with smp_call_function() Thomas Schlichter
2003-02-26 9:27 ` Andrew Morton
2003-02-26 10:37 ` Dave Jones
2003-02-26 9:54 ` Andrew Morton
2003-02-26 10:14 ` Thomas Schlichter
2003-02-26 11:19 ` Dave Jones
2003-02-26 10:28 ` Andrew Morton
2003-02-26 10:52 ` Thomas Schlichter
2003-02-26 11:28 ` Dave Jones
2003-02-26 13:39 ` Alan Cox
2003-02-26 18:47 ` Andrew Morton [this message]
2003-02-26 20:11 ` Alan Cox
2003-02-26 16:00 ` Martin J. Bligh
-- strict thread matches above, loose matches on Subject: below --
2003-02-21 14:20 [PATCH][2.5] replace flush_map() in arch/i386/mm/pageattr.c w ith flush_tlb_all() Dave Jones
2003-02-21 17:36 ` Dave Jones
2003-02-22 3:23 ` [PATCH][2.5] fix preempt-issues with smp_call_function() Thomas Schlichter
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