Re: [PATCH] (4/4) use system get_random_bytes in hdlcdrv

[Andi Kleen <ak@xxxxxxx>]

>  void hdlcdrv_arbitrate(struct net_device *dev, struct hdlcdrv_state *s)
>  {
> +     u8 prand;
> +
>       if (!s || s->magic != HDLCDRV_MAGIC || s->hdlctx.ptt || !s->skb) 
>               return;
>       if (s->ch_params.fulldup) {
> @@ -459,7 +452,9 @@
>       if ((--s->hdlctx.slotcnt) > 0)
>               return;
>       s->hdlctx.slotcnt = s->ch_params.slottime;
> -     if ((random_num() % 256) > s->ch_params.ppersist)
> +
> +     get_random_bytes(&prand, sizeof(prand));
> +     if (prand > s->ch_params.ppersist)

The "hard" random numbers generated by get_random_bytes
are a precious scarce resource (many systems don't generate them very often).
They should only be used as seed or when it is needed for security, otherwise
users who really need them risk blocking on /dev/random.
Especially if that function is called often it would be a bad idea.

-Andi