Re: [PATCH 1/8] Introduce slices

[Sascha Hauer <s.hauer@pengutronix.de>]

On Mon, Mar 09, 2020 at 03:49:53PM +0100, Daniel Glöckner wrote:
> Hello Sascha,
> 
> Am 03/06/20 um 20:33 schrieb Sascha Hauer:
> > +static void __slice_acquire(struct slice *slice, int add)
> > +{
> > +	struct slice_entry *se;
> > +
> > +	slice->acquired += add;
> > +
> > +	if (slice->acquired < 0) {
> > +		pr_err("Slice %s acquired count drops below zero\n",
> > +			slice_name(slice));
> > +		dump_stack();
> > +		slice->acquired = 0;
> > +		return;
> > +	}
> > +
> > +	list_for_each_entry(se, &slice->deps, list)
> > +		__slice_acquire(se->slice, add);
> 
> I don't think we need that loop. slice_acquired will already recurse into
> the dependency tree. That loop would also mark resources as used which
> are still unused. The network packet handlers can safely do MDIO transfers
> because the network stack does not talk to the PHY while checking for
> received packets.

Agreed.

> 
> > +bool slice_acquired(struct slice *slice)
> > +{
> > +	struct slice_entry *se;
> > +
> > +	if (slice->acquired)
> > +		return true;
> > +
> > +	list_for_each_entry(se, &slice->deps, list)
> > +		if (slice_acquired(se->slice))
> > +			return true;
> > +
> > +	return false;
> > +}
> 
> It would be nice if this function was able to detect cyclic dependencies
> if DEBUG. This can be done by setting slice->acquired to INT_MIN while
> recursing and checking if any of the values found are negative.

Yes, good idea.

I'll send an update for this.

Sascha

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox