Re: [PATCH-RFC 2/2] eventfd: EFD_STATE flag

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On 08/04/2009 11:54 AM, Michael S. Tsirkin wrote:
On Tue, Aug 04, 2009 at 11:53:03AM +0300, Avi Kivity wrote:
On 08/03/2009 07:57 PM, Michael S. Tsirkin wrote:
Why not do it at the point of the write?

      if (value != ctx->count) {
          ctx->count = value;
          wake_things_up();
      }

What if write comes before read?

The read will get the new value.

Yes :) But how does read know it should not block?

If a different read comes after the write but after our read, it will have transferred the value, resulting in the same situation.

I think reads should never block with a state based mechanism.

--
error compiling committee.c: too many arguments to function

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