Re: [RFC/T][PATCH v2 2/3] rc80211-pid: introduce PID sharpening factor

[Stefano Brivio <stefano.brivio@polimi.it>]

On Mon, 10 Dec 2007 07:28:01 +0100
Mattias Nissler <mattias.nissler@gmx.de> wrote:

> > -	/* If no frames were transmitted, we assume the old sample is
> > -	 * still a good measurement and copy it. */
> > -	if (spinfo->tx_num_xmit == 0)
> > -		pf = spinfo->last_pf;
> 
> Please don't remove this check. We can never know when anybody starts
> calling rate_control_pid_sample() without packets transmitted. Then it's
> good to have it, else we divide by zero in the next line.

But, as you said, rate_control_pid_sample() only gets called by
rate_control_pid_tx_status(). There, spinfo->tx_num_xmit always get
increased. The only other spot where spinfo->tx_num_xmit gets changed is in
rate_control_pid_sample(), where we set it to 0 after that that division
gets done, and we obviously change its value after having been called by
rate_control_pid_tx_status(). So, it always get increased before the
division, and it's never set to a negative value. Therefore, I assume that
it will never be zero in the division. Am I wrong?


--
Ciao
Stefano