Re: [PATCHv2 1/3] eventfd: allow atomic read and waitqueue remove

[Michael S. Tsirkin]

On Thu, Jan 21, 2010 at 09:50:34AM -0800, Davide Libenzi wrote:
> On Thu, 21 Jan 2010, Avi Kivity wrote:
> 
> > On 01/21/2010 07:32 PM, Michael S. Tsirkin wrote:
> > > 
> > > > Can't you read from the file?
> > > >      
> > > IMO no, the read could block.
> > >    
> > 
> > But you're in process context.  An eventfd never blocks.
> 
> Can you control the eventfd flags? Because if yes, O_NONBLOCK will never 
> block.
> 

Userspace can but kvm can't.

> 
> - Davide
> 
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