lkml.org 
[lkml]   [2012]   [Jun]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2 4/6] kvm: Extend irqfd to support level interrupts
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.


\
 
 \ /
  Last update: 2012-06-28 14:21    [W:0.083 / U:0.500 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site