On Thu, 27 Aug 2009, Paolo Bonzini wrote:
> > Ok, so why not using the eventfd counter as state?
> > On the device side:
> >
> > void write_state(int sfd, int state) {
> > u64 cnt;
> >
> > /* Clear the current state, sfd is in non-blocking mode */
> > read(sfd,&cnt, sizeof(cnt));
> > /* Writes new state */
> > cnt = 1 + !!state;
> > write(sfd,&cnt, sizeof(cnt));
> > }
>
> It's interesting [no sarcasm intended, mind] that EFD_SEMAPHORE was
> added exactly to avoid a read+write combination for the case of
> decrementing a value.
Like I repeated 25 times already, EFD_SEMAPHORE was added, because a
*semaphore* is a pretty widely known and used abstraction.
- Davide
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