Re: [PATCH 1/1] eventfd: implementation of EFD_MASK flag

[Martin Sustrik]

On 08/02/13 07:36, Andy Lutomirski wrote:

> > On 08/02/13 02:03, Andy Lutomirski wrote:
> > > There may be some
> > > advantage to adding (later on, if needed) an option to change the
> > > flags set in:
> > >
> > > +               if (waitqueue_active(&ctx->wqh))
> > > +                       wake_up_locked_poll(&ctx->wqh,
> > > +                               (unsigned long)ctx->mask.events);
> > >
> > > (i.e. to allow the second parameter to omit some bits that were
> > > already signaled.)  Allowing write to write a bigger struct in the
> > > future won't break anything.
> >
> >
> > I think I don't follow. Either the second parameter is supposed to be
> > *newly* signaled events, in which case the events that were already signaled
> > in the past should be ommitted, or it is meant to be *all* signaled events,
> > in which case the current implementation is OK.
>
> I defer to the experts here.  But I suspect that if you want to
> perfectly emulate sockets, you may need to vary what you specify.
> (IIRC tcp sockets report an EPOLLIN edge every time data is received
> even if the receive buffer wasn't empty.)

Hm. That sounds like leaking protocol implementation details to the 
user. That's a bad design IMO and should not be encouraged.

Anyway, I have implemented your other suggestions.

Btw, one thing I am not sure about is how to submit improved patches to 
the ML. Should I use the same patch name? Doesn't that cause confusion?

Martin
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