Re: poll() in 2.6 and beyond

[Linus Torvalds]

On Wed, 3 Mar 2004, Richard B. Johnson wrote:
> 
> And YES! If I clear the flag only after it is read. It "fixes" the
> observed problem!

Ok. That solves one problem, but it does seem to point to the fact that 
2.6.x calls down to poll() more than 2.4.x does.

It really _is_ normal to have multiple calls to "poll()" for the same fd 
as a result of a single "poll()" system call, but if we actually get a 
positive hit (ie the ->poll() call returns a bit that we consider to be a 
success by comparing it to what we _wanted_ to see), then we should have 
stopped doing that.

And since your test program always sets "POLLIN", any ->poll() call that 
has the POLLIN flag set should have ended up being the last one (since it 
would have marked a "success"). 

So there's still something I don't understand, and that seems to differ
between 2.4.x and 2.6.x. Can anybody else see it?

		Linus
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