linux-kernel - Re: [PATCH 4/5] iommu: Make sure a device is always attached to a domain

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Message-ID: <20150130122919.GD3702@8bytes.org>
Date:	Fri, 30 Jan 2015 13:29:19 +0100
From:	Joerg Roedel <joro@...tes.org>
To:	Will Deacon <will.deacon@....com>
Cc:	"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
	Kukjin Kim <kgene@...nel.org>,
	David Woodhouse <dwmw2@...radead.org>,
	Heiko Stuebner <heiko@...ech.de>,
	Hiroshi Doyu <hdoyu@...dia.com>,
	Thierry Reding <thierry.reding@...il.com>,
	Alex Williamson <alex.williamson@...hat.com>,
	Arnd Bergmann <arnd@...db.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Robin Murphy <Robin.Murphy@....com>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	"jroedel@...e.de" <jroedel@...e.de>
Subject: Re: [PATCH 4/5] iommu: Make sure a device is always attached to a
 domain

On Wed, Jan 28, 2015 at 02:38:52PM +0000, Will Deacon wrote:
> On Tue, Jan 27, 2015 at 12:08:58AM +0000, Joerg Roedel wrote:
> > -	return iommu_group_for_each_dev(group, domain,
> > -					iommu_group_do_attach_device);
> > +	int ret;
> > +
> > +	if (group->default_domain && group->domain != group->default_domain)
> > +		return -EBUSY;
> 
> I think this is now racy with itself and detach, whereas before we always
> held the group->mutex by virtue of iommu_group_for_each_dev.

You are right, thanks. I will update the code with correct locking.


	Joerg

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