linux-kernel - Re: [patch 15/15] PNP: convert resource options to single linked list

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Message-Id: <200806041526.19234.bjorn.helgaas@hp.com>
Date:	Wed, 4 Jun 2008 15:26:17 -0600
From:	Bjorn Helgaas <bjorn.helgaas@...com>
To:	Rene Herman <rene.herman@...access.nl>
Cc:	Len Brown <lenb@...nel.org>, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org, Adam Belay <ambx1@....rr.com>,
	Adam M Belay <abelay@....edu>,
	Li Shaohua <shaohua.li@...el.com>,
	Matthieu Castet <castet.matthieu@...e.fr>,
	Thomas Renninger <trenn@...e.de>,
	Jaroslav Kysela <perex@...ex.cz>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Takashi Iwai <tiwai@...e.de>
Subject: Re: [patch 15/15] PNP: convert resource options to single linked list

On Tuesday 03 June 2008 03:13:37 pm Rene Herman wrote:
> On 31-05-08 00:49, Bjorn Helgaas wrote:
> 
> Forgot this comment:
> 
> > --- work10.orig/drivers/pnp/quirks.c	2008-05-30 15:58:14.000000000 -0600
> > +++ work10/drivers/pnp/quirks.c	2008-05-30 15:58:15.000000000 -0600
> 
> > +static struct pnp_option *pnp_clone_dependent_set(struct pnp_dev *dev,
> > +						  unsigned int set)
> >  {
> > -	struct pnp_option *head = NULL;
> > -	struct pnp_option *prev = NULL;
> > -	struct pnp_option *res;
> > -
> > -	/*
> > -	 * Build a functional IRQ-optional variant of each MPU option.
> > -	 */
> > -
> > -	for (res = dev->dependent; res; res = res->next) {
> > -		struct pnp_option *curr;
> > -		struct pnp_port *port;
> > -		struct pnp_port *copy_port;
> > -		struct pnp_irq *irq;
> > -		struct pnp_irq *copy_irq;
> > -
> > -		port = res->port;
> > -		irq = res->irq;
> > -		if (!port || !irq)
> > -			continue;
> > +	struct pnp_option *tail = NULL, *first_new_option = NULL;
> > +	struct pnp_option *option, *new_option;
> > +	unsigned int flags;
> > +
> > +	list_for_each_entry(option, &dev->options, list) {
> > +		if (pnp_option_is_dependent(option))
> > +			tail = option;
> > +	}
> > +	if (!tail) {
> > +		dev_err(&dev->dev, "no dependent option sets\n");
> > +		return NULL;
> > +	}
> >  
> > -		copy_port = pnp_alloc(sizeof *copy_port);
> > -		if (!copy_port)
> > -			break;
> > -
> > -		copy_irq = pnp_alloc(sizeof *copy_irq);
> > -		if (!copy_irq) {
> > -			kfree(copy_port);
> > -			break;
> > -		}
> > +	flags = pnp_dependent_option(dev, PNP_RES_PRIORITY_FUNCTIONAL);
> > +	list_for_each_entry(option, &dev->options, list) {
> > +		if (pnp_option_is_dependent(option) &&
> > +		    pnp_option_set(option) == set) {
> > +			new_option = kmalloc(sizeof(struct pnp_option),
> > +					     GFP_KERNEL);
> > +			if (!new_option) {
> > +				dev_err(&dev->dev, "couldn't clone dependent "
> > +					"set %d\n", set);
> > +				return NULL;
> > +			}
> >  
> > -		*copy_port = *port;
> > -		copy_port->next = NULL;
> > +			*new_option = *option;
> > +			new_option->flags = flags;
> > +			if (!first_new_option)
> > +				first_new_option = new_option;
> >  
> > -		*copy_irq = *irq;
> > -		copy_irq->flags |= IORESOURCE_IRQ_OPTIONAL;
> > -		copy_irq->next = NULL;
> > -
> > -		curr = pnp_build_option(PNP_RES_PRIORITY_FUNCTIONAL);
> > -		if (!curr) {
> > -			kfree(copy_port);
> > -			kfree(copy_irq);
> > -			break;
> > +			list_add(&new_option->list, &tail->list);
> > +			tail = new_option;
> >  		}
> > -		curr->port = copy_port;
> > -		curr->irq = copy_irq;
> > -
> > -		if (prev)
> > -			prev->next = curr;
> > -		else
> > -			head = curr;
> > -		prev = curr;
> >  	}
> > -	if (head)
> > -		dev_info(&dev->dev, "adding IRQ-optional MPU options\n");
> >  
> > -	return head;
> > +	return first_new_option;
> >  }
> 
> This works, but I did the "disconnected chain build" that I did due to 
> finding it particularly clumsy to add to the dependent chain while 
> walking it.
> 
> This avoids actual problems due to num_sets = dev->num_dependents_sets 
> in caller and the pnp_option_set(option) == set in the loop (not unlike 
> the first version of the original checked for a present irq) but it's 
> again checking the options it just added itself.
> 
> If you feel that's perfectly fine then <shrug> but thought I'd still 
> remark on it in case it wasn't intentional.

Hmmm...  I think I see what you mean.  It should work as-is, but
maybe it'd be more elegant to build the new list separately and use
list_splice to insert it.

Guess I'll wait for you to confirm whether we can rip out the list
clone altogether before trying this out.

Bjorn
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