From: "Michael S. Tsirkin" <mst@redhat.com>
To: Gleb Natapov <gleb@redhat.com>
Cc: Alex Williamson <alex.williamson@redhat.com>,
avi@redhat.com, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, jan.kiszka@siemens.com
Subject: Re: [PATCH v2 4/6] kvm: Extend irqfd to support level interrupts
Date: Thu, 28 Jun 2012 11:41:05 +0300 [thread overview]
Message-ID: <20120628084105.GE12447@redhat.com> (raw)
In-Reply-To: <20120628083541.GN6533@redhat.com>
On Thu, Jun 28, 2012 at 11:35:41AM +0300, Gleb Natapov wrote:
> On Thu, Jun 28, 2012 at 11:34:35AM +0300, Michael S. Tsirkin wrote:
> > On Thu, Jun 28, 2012 at 09:34:31AM +0300, Gleb Natapov wrote:
> > > On Thu, Jun 28, 2012 at 01:31:29AM +0300, Michael S. Tsirkin wrote:
> > > > On Wed, Jun 27, 2012 at 04:04:18PM -0600, Alex Williamson wrote:
> > > > > On Wed, 2012-06-27 at 18:26 +0300, Michael S. Tsirkin wrote:
> > > > > > On Tue, Jun 26, 2012 at 11:09:46PM -0600, Alex Williamson wrote:
> > > > > > > @@ -71,6 +130,14 @@ irqfd_inject(struct work_struct *work)
> > > > > > > kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0);
> > > > > > > }
> > > > > > >
> > > > > > > +static void
> > > > > > > +irqfd_inject_level(struct work_struct *work)
> > > > > > > +{
> > > > > > > + struct _irqfd *irqfd = container_of(work, struct _irqfd, inject);
> > > > > > > +
> > > > > > > + kvm_set_irq(irqfd->kvm, irqfd->source->id, irqfd->gsi, 1);
> > > > > > > +}
> > > > > > > +
> > > > > > > /*
> > > > > > > * Race-free decouple logic (ordering is critical)
> > > > > > > */
> > > > > >
> > > > > >
> > > > > > Why is it safe to ignore return value here?
> > > > > > needs a comment.
> > > > >
> > > > > Well, it seems like you and Gleb came to the conclusion that it's safe,
> > > > > but I can really follow from the list thread. Can you explain and I'll
> > > > > add a comment? Thanks,
> > > > >
> > > > > Alex
> > > >
> > > > We merely talked about edge interrupts.
> > > >
> > > In fact it would have been nice to return -EBUSY when write() to level
> > > irqfd is coalesced.
> >
> > Possibly nice but not really practical.
> >
> What do you mean by that? Impossible to implement or not useful?
Impossible to implement and also does not match normal eventfd
semantics.
> --
> Gleb.
next prev parent reply other threads:[~2012-06-28 8:41 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-27 5:08 [PATCH v2 0/6] kvm: level triggered irqfd support Alex Williamson
2012-06-27 5:09 ` [PATCH v2 1/6] kvm: Pass kvm_irqfd to functions Alex Williamson
2012-06-27 9:35 ` Michael S. Tsirkin
2012-06-27 14:30 ` Alex Williamson
2012-06-27 14:24 ` Cornelia Huck
2012-06-28 8:38 ` Michael S. Tsirkin
2012-06-28 9:03 ` Cornelia Huck
2012-06-28 9:34 ` Michael S. Tsirkin
2012-06-28 12:00 ` Cornelia Huck
2012-06-28 12:09 ` Michael S. Tsirkin
2012-06-28 16:51 ` Cornelia Huck
2012-06-28 16:56 ` Michael S. Tsirkin
2012-06-29 15:14 ` Alex Williamson
2012-06-27 5:09 ` [PATCH v2 2/6] kvm: Add missing KVM_IRQFD API documentation Alex Williamson
2012-06-27 9:53 ` Michael S. Tsirkin
2012-06-27 5:09 ` [PATCH v2 3/6] kvm: Sanitize KVM_IRQFD flags Alex Williamson
2012-06-27 9:21 ` Michael S. Tsirkin
2012-06-27 20:12 ` Alex Williamson
2012-06-27 20:22 ` Michael S. Tsirkin
2012-06-28 12:35 ` Avi Kivity
2012-06-27 5:09 ` [PATCH v2 4/6] kvm: Extend irqfd to support level interrupts Alex Williamson
2012-06-27 9:34 ` Michael S. Tsirkin
2012-06-27 21:19 ` Alex Williamson
2012-06-28 12:41 ` Avi Kivity
2012-06-27 9:51 ` Michael S. Tsirkin
2012-06-27 20:59 ` Alex Williamson
2012-06-27 21:14 ` Michael S. Tsirkin
2012-06-27 21:28 ` Alex Williamson
2012-06-27 22:28 ` Michael S. Tsirkin
2012-06-28 3:52 ` Alex Williamson
2012-06-28 8:29 ` Michael S. Tsirkin
2012-06-29 15:13 ` Alex Williamson
2012-06-27 15:26 ` Michael S. Tsirkin
2012-06-27 22:04 ` Alex Williamson
2012-06-27 22:31 ` Michael S. Tsirkin
2012-06-28 6:34 ` Gleb Natapov
2012-06-28 8:34 ` Michael S. Tsirkin
2012-06-28 8:35 ` Gleb Natapov
2012-06-28 8:41 ` Michael S. Tsirkin [this message]
2012-06-28 8:46 ` Gleb Natapov
2012-06-28 8:48 ` Michael S. Tsirkin
2012-06-28 8:53 ` Gleb Natapov
2012-06-29 22:27 ` Alex Williamson
2012-07-01 7:34 ` Gleb Natapov
2012-06-27 5:10 ` [PATCH v2 5/6] kvm: KVM_EOIFD, an eventfd for EOIs Alex Williamson
2012-06-27 9:49 ` Michael S. Tsirkin
2012-06-27 13:58 ` Gleb Natapov
2012-06-27 14:29 ` Alex Williamson
2012-06-27 14:51 ` Gleb Natapov
2012-06-28 3:55 ` Alex Williamson
2012-06-28 13:11 ` Michael S. Tsirkin
2012-06-28 14:08 ` Gleb Natapov
2012-06-28 16:55 ` Michael S. Tsirkin
2012-06-27 15:20 ` Michael S. Tsirkin
2012-06-28 19:29 ` Michael S. Tsirkin
2012-06-29 15:09 ` Alex Williamson
2012-06-29 15:12 ` Alex Williamson
2012-06-27 5:10 ` [PATCH v2 6/6] kvm: Level IRQ de-assert for KVM_IRQFD Alex Williamson
2012-06-28 12:59 ` Avi Kivity
2012-06-29 15:39 ` Alex Williamson
2012-06-27 9:15 ` [PATCH v2 0/6] kvm: level triggered irqfd support Michael S. Tsirkin
2012-06-27 9:58 ` Michael S. Tsirkin
2012-06-27 14:33 ` Alex Williamson
2012-06-28 8:42 ` Michael S. Tsirkin
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