Messages in this thread | | | Date | Wed, 26 Aug 2009 12:44:10 -0700 (PDT) | From | Davide Libenzi <> | Subject | Re: [PATCH 0/2] eventfd: new EFD_STATE flag |
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On Wed, 26 Aug 2009, Avi Kivity wrote:
> On 08/26/2009 10:13 PM, Davide Libenzi 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)); > > } > > > > > > On the hypervisor side: > > > > int read_state(int sfd) { > > u64 cnt; > > > > read(sfd,&cnt, sizeof(cnt)); > > return state - 1; > > } > > > > > > Hadn't though of read+write as set. While the 1+ is a little ugly, it's > workable.
Pick what you want, as long as it always writes something != 0 :)
> I see no kernel equivalent to read(), but that's easily done.
Adding an in-kernel read based on "ctx", that is no problem at all.
- Davide
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