From: Jan Kiszka <jan.kiszka@siemens.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Avi Kivity <avi@redhat.com>,
Alex Williamson <alex.williamson@redhat.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"mtosatti@redhat.com" <mtosatti@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"yongjie.ren@intel.com" <yongjie.ren@intel.com>
Subject: Re: [PATCH] KVM: Use IRQF_ONESHOT for assigned device MSI interrupts
Date: Mon, 04 Jun 2012 15:16:33 +0200 [thread overview]
Message-ID: <4FCCB531.4000008@siemens.com> (raw)
In-Reply-To: <alpine.LFD.2.02.1206041458490.3086@ionos>
On 2012-06-04 15:07, Thomas Gleixner wrote:
> On Mon, 4 Jun 2012, Jan Kiszka wrote:
>> On 2012-06-04 13:21, Thomas Gleixner wrote:
>> So this shortcut requires some checks before being applied to a specific
>> MSI/MSI-X vector.
>>
>>
>> Taking KVM aside, my general question remains if threaded MSI handlers
>> of all devices really need to apply IRQF_ONESHOT though they should have
>> no use for it.
>
> In theory no, but we had more than one incident, where threaded irqs
> w/o a primary handler and w/o IRQF_ONEHSOT lead to full system
> starvation. Linus requested this sanity check and I think it's sane
> and required.
OK.
>
> In fact it's a non issue for MSI. MSI uses handle_edge_irq which does
> not mask the interrupt. IRQF_ONESHOT is a noop for that flow handler.
Isn't irq_finalize_oneshot processes for all flows?
Jan
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
next prev parent reply other threads:[~2012-06-04 13:16 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-01 16:16 [PATCH] KVM: Use IRQF_ONESHOT for assigned device MSI interrupts Alex Williamson
2012-06-01 16:39 ` Jan Kiszka
2012-06-01 17:03 ` Alex Williamson
2012-06-01 17:14 ` Jan Kiszka
2012-06-01 17:59 ` Alex Williamson
2012-06-01 18:26 ` Jan Kiszka
2012-06-03 8:42 ` Avi Kivity
2012-06-04 11:21 ` Thomas Gleixner
2012-06-04 11:40 ` Jan Kiszka
2012-06-04 13:07 ` Thomas Gleixner
2012-06-04 13:16 ` Jan Kiszka [this message]
2012-06-04 13:22 ` Thomas Gleixner
2012-06-08 7:47 ` Michael S. Tsirkin
2012-06-08 7:55 ` Jan Kiszka
2012-06-08 8:00 ` Michael S. Tsirkin
2012-06-08 8:03 ` Jan Kiszka
2012-06-08 14:39 ` Michael S. Tsirkin
2012-06-08 14:50 ` Jan Kiszka
2012-06-11 10:01 ` Avi Kivity
2012-06-11 10:21 ` Michael S. Tsirkin
2012-06-18 8:46 ` Ren, Yongjie
2012-06-18 11:00 ` Avi Kivity
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