[ECOS] Re: What causes interrupted network system calls?

[Grant Edwards <grant.b.edwards@gmail.com>]

On 2009-10-29, Nick Garnett <nickg@ecoscentric.com> wrote:
>  Grant Edwards <grant.b.edwards@gmail.com> writes:
>
> If you don't have the POSIX package then there won't be any
> signal deliver of the sort that could affect the net stack.

That's what I thought.

> The net stack interprets any return from an event signal that
> is not a proper signal or a timeout as an interrupt and
> returns EINTR. If POSIX is not included then something else
> must be forcing that thread out of the semaphore wait. Perhaps
> there are other parts of the system that call
> cyg_thread_release()

Yep, I just realized that any call to cyg_thread_release() on a
thread that's doing network stuff could cause an EINTR.  I
don't think "signals" (in the POSIX/libc sense) have anything
to do with it.

> and may be zapping the wrong thread. Or perhaps the right
> thread at the wrong time.

I'm now betting it's going to turn out to be the latter.  It
looks like there is a case where one task calls
cyg_thread_release() to wake up another task (which I think is
the task that's seeing the EINTR).  That bit of synchronization
should probably be done with an event flag or something...

-- 
Grant Edwards                   grante             Yow! Is my fallout shelter
                                  at               termite proof?
                               visi.com            


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