Re: [CRASH] in tulip driver?

From: Andrew Morton (akpm@zip.com.au)
Date: Thu Jul 11 2002 - 15:44:30 EST


Jussi Laako wrote:
>
> ...
> >
> > --- 2.4.19-pre6/drivers/char/random.c~low-latency Fri Apr 5 12:11:17 2002
> > +++ 2.4.19-pre6-akpm/drivers/char/random.c Fri Apr 5 12:11:17 2002
> > @@ -1369,6 +1369,11 @@ static ssize_t extract_entropy(struct en
> > buf += i;
> > ret += i;
> > add_timer_randomness(&extract_timer_state, nbytes);
> > +#if LOWLATENCY_NEEDED
> > + /* This can happen in softirq's, but that's what we want */
> > + if (conditional_schedule_needed())
> > + break;
> > +#endif
> > }
> >
> > /* Wipe data just returned from memory */
> >
> > So it's a bit of a mystery. It seems to think that it has
> > EXTRACT_ENTROPY_USER.
>
> Whoops, thanks, I found the bug. My fault...
>
> That "break;" breaks some (apparently broken) programs that don't expect
> read of /dev/urandom to return early. For security resons (to get
> identical behaviour compared to the original kernel) I made a fix that
> someone proposed. That fix is apparently broken on some rare situations
> which seem to be difficult to trigger (requires high overall irq rates
> with network load). Now I'm going to remove that part completely and see
> what happens next...
>

Yes, just delete that chunk. I took it out of the ll patch a few
weeks ago because of the /dev/urandom thing.

The random driver only causes a 1-2 milliseocnd blip @500MHz anyway.

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