On 16/08/18 11:58, Hans Verkuil wrote: >>> +On success :c:func:`poll() <request-func-poll>` returns the number of file >>> +descriptors that have been selected (that is, file descriptors for which >>> the +``revents`` field of the respective struct :c:type:`pollfd` >>> +is non-zero). Request file descriptor set the ``POLLPRI`` flag in >>> ``revents`` +when the request was completed. When the function times out >>> it returns +a value of zero, on failure it returns -1 and the ``errno`` >>> variable is +set appropriately. >>> + >>> +Attempting to poll for a request that is completed or not yet queued will >>> +set the ``POLLERR`` flag in ``revents``. >> >> Why should a completed request set POLLERR, given that the purpose of poll() >> is to poll for completion ? > > I think you are right. We should just always set POLLPRI for completed requests. > I'll change that. I checked the code, and this is actually what happens already. So the text should read: "Attempting to poll for a request that is not yet queued will set the ``POLLERR`` flag in ``revents``." I'll update this. Regards, Hans
