From: "Jan Beulich" <JBeulich@novell.com>
To: Keir Fraser <keir.fraser@eu.citrix.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>,
"Xen-devel@lists.xensource.com" <Xen-devel@lists.xensource.com>,
Tom Kopec <tek@acm.org>,
Daniel Stodden <Daniel.Stodden@citrix.com>
Subject: Re: [GIT PULL] Fix lost interrupt race in Xen event channels
Date: Mon, 30 Aug 2010 10:22:24 +0100 [thread overview]
Message-ID: <4C7B94700200007800012C74@vpn.id2.novell.com> (raw)
In-Reply-To: <C8A1354E.2155C%keir.fraser@eu.citrix.com>
>>> On 30.08.10 at 11:15, Keir Fraser <keir.fraser@eu.citrix.com> wrote:
> On 30/08/2010 10:06, "Jan Beulich" <JBeulich@novell.com> wrote:
>
>> However, do you also think that pirq_unmask_and_notify() is safe
>> to be called twice? I would think the double EOI potentially sent to
>> Xen could lead to an interrupt getting ack-ed that didn't even get
>> started to be serviced yet.
>
> Erm, well if this is a race that happens only occasionally, does it matter?
> Worst case you get another interrupt straight away. Only a problem if it
> happens often enough to cause a performance issue or even livelock interrupt
> storm.
I wasn't worried about the level case, but rather the edge one. I
forgot, however, that edge ones are ACKTYPE_NONE in Xen, so
indeed there shouldn't be a problem unless IRQs get moved
around at a very high rate (which clearly they shouldn't).
Jan
next prev parent reply other threads:[~2010-08-30 9:22 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-24 21:35 [GIT PULL] Fix lost interrupt race in Xen event channels Jeremy Fitzhardinge
2010-08-25 7:52 ` [Xen-devel] " Jan Beulich
2010-08-25 10:04 ` Daniel Stodden
2010-08-25 11:24 ` Jan Beulich
2010-08-25 17:54 ` Jeremy Fitzhardinge
2010-08-26 6:46 ` Jan Beulich
2010-08-26 16:32 ` Jeremy Fitzhardinge
2010-08-27 8:56 ` Jan Beulich
2010-08-27 20:43 ` Daniel Stodden
2010-08-27 21:49 ` Daniel Stodden
2010-08-27 23:43 ` Jeremy Fitzhardinge
2010-08-30 8:03 ` Jan Beulich
2010-08-30 8:43 ` Jan Beulich
2010-08-30 8:48 ` Keir Fraser
2010-08-30 9:06 ` Jan Beulich
2010-08-30 9:15 ` Keir Fraser
2010-08-30 9:22 ` Jan Beulich [this message]
2010-08-30 16:36 ` Jeremy Fitzhardinge
2010-08-31 6:38 ` Jan Beulich
2010-09-03 18:46 ` Using handle_fasteoi_irq for pirqs Jeremy Fitzhardinge
2010-09-06 7:58 ` Jan Beulich
2010-09-07 1:53 ` Jeremy Fitzhardinge
2010-09-07 6:58 ` Jan Beulich
2010-09-07 8:02 ` Jeremy Fitzhardinge
2010-09-07 8:58 ` Jan Beulich
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