linux-kernel - Re: [patch 15/18] PNP: support optional IRQ resources

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4853814D.4010309@keyaccess.nl>
Date:	Sat, 14 Jun 2008 10:29:01 +0200
From:	Rene Herman <rene.herman@...access.nl>
To:	Bjorn Helgaas <bjorn.helgaas@...com>
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 15/18] PNP: support optional IRQ resources

On 05-06-08 00:09, Bjorn Helgaas wrote:

> This patch adds an IORESOURCE_IRQ_OPTIONAL flag for use when
> assigning resources to a device.  If the flag is set and we are
> unable to assign an IRQ to the device, we can leave the IRQ
> disabled but allow the overall resource allocation to succeed.
> 
> Some devices request an IRQ, but can run without an IRQ
> (possibly with degraded performance).  This flag lets us run
> the device without the IRQ instead of just leaving the
> device disabled.
> 
> This is a reimplementation of this previous change by Rene
> Herman <rene.herman@...il.com>:
>     http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=3b73a223661ed137c5d3d2635f954382e94f5a43
> 
> I reimplemented this for two reasons:
>     - to prepare for converting all resource options into a single linked
>       list, as opposed to the per-resource-type lists we have now, and
>     - to preserve the order and number of resource options.
> 
> In PNPBIOS and ACPI, we configure a device by giving firmware a
> list of resource assignments.  It is important that this list
> has exactly the same number of resources, in the same order,
> as the "template" list we got from the firmware in the first
> place.
> 
> The problem of a sound card MPU401 being left disabled for want of
> an IRQ was reported by Uwe Bugla <uwe.bugla@....de>.
> 
> Signed-off-by: Bjorn Helgaas <bjorn.helgaas@...com>

You rework this again in the later patch doing the final switch over 
after which things end up right but also already at this point:

> @@ -176,33 +184,10 @@ static void quirk_ad1815_mpu_resources(s
>  	if (!irq || irq->next)
>  		return;
>  
> -	res = dev->dependent;
> -	if (!res)
> -		return;
> -
> -	while (1) {
> -		struct pnp_irq *copy;
> -
> -		copy = pnp_alloc(sizeof *copy);
> -		if (!copy)
> -			break;
> -
> -		bitmap_copy(copy->map.bits, irq->map.bits, PNP_IRQ_NR);
> -		copy->flags = irq->flags;
> -
> -		copy->next = res->irq; /* Yes, this is NULL */
> -		res->irq = copy;
> -
> -		if (!res->next)
> -			break;
> -		res = res->next;
> -	}
> -	kfree(irq);
> +	irq->flags |= IORESOURCE_IRQ_OPTIONAL;
> +	dev_info(&dev->dev, "made independent IRQ optional\n");
>  
>  	res->next = quirk_isapnp_mpu_options(dev);

... this line should just go.

Previously "res" ended up as the last dependent set through the while 
loop but now it's the independendent set which in this previous setup of 
things shouldn't even have a ->next. Just deleting this line makes this 
patch fine and

Acked-by: Rene Herman <rene.herman@...il.com>

Rene.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/