From mboxrd@z Thu Jan  1 00:00:00 1970
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: Re: [PATCH 07/15] [swiotlb] In 'swiotlb_free' check
	iommu_sw pointer.
Date: Tue, 19 Jan 2010 12:45:26 -0500
Message-ID: <20100119174526.GN11986@phenom.dumpdata.com>
References: <1263510064-16788-1-git-send-email-konrad.wilk@oracle.com>
	<1263510064-16788-2-git-send-email-konrad.wilk@oracle.com>
	<1263510064-16788-3-git-send-email-konrad.wilk@oracle.com>
	<1263510064-16788-4-git-send-email-konrad.wilk@oracle.com>
	<1263510064-16788-5-git-send-email-konrad.wilk@oracle.com>
	<1263510064-16788-6-git-send-email-konrad.wilk@oracle.com>
	<1263510064-16788-7-git-send-email-konrad.wilk@oracle.com>
	<1263510064-16788-8-git-send-email-konrad.wilk@oracle.com>
	<20100115020240.GG6021@sequoia.sous-sol.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Return-path: <xen-devel-bounces@lists.xensource.com>
Content-Disposition: inline
In-Reply-To: <20100115020240.GG6021@sequoia.sous-sol.org>
List-Unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
List-Post: <mailto:xen-devel@lists.xensource.com>
List-Help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-Subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
Sender: xen-devel-bounces@lists.xensource.com
Errors-To: xen-devel-bounces@lists.xensource.com
To: Chris Wright <chrisw@sous-sol.org>
Cc: Ian.Campbell@eu.citrix.com, jeremy@goop.org, xen-devel@lists.xensource.com, joerg.roedel@amd.com, fujita.tomonori@lab.ntt.co.jp, iommu@lists.linux-foundation.org, dwmw2@infradead.org, alex.williamson@hp.com
List-Id: xen-devel@lists.xenproject.org

On Thu, Jan 14, 2010 at 06:02:40PM -0800, Chris Wright wrote:
> * Konrad Rzeszutek Wilk (konrad.wilk@oracle.com) wrote:
> > --- a/lib/swiotlb.c
> > +++ b/lib/swiotlb.c
> > @@ -364,7 +364,7 @@ cleanup1:
> >  
> >  void __init swiotlb_free(void)
> >  {
> > -	if (!iommu_sw->overflow_buffer)
> > +	if (!iommu_sw)
> >  		return;
> >  
> 
> Sure this is safe for the case where allocation failed?  Wouldn't this
> do free_late_bootmem(__pa(0))?

That would indeed fail, but alloc_bootmem_low_pages (___alloc_bootmem)
panics the machine if it can't allocate the buffer. So we would never
actually get to swiotlb_free if we failed to allocate the buffers for
SWIOTLB.

But for the case where the SWIOTLB allocation happens when using 
swiotlb_late_init_with_default_size, and it fails, this check
is not sufficient. I will add a check for that or just make
swiotlb_late_init_with_default_size set iommu_sw to NULL when
the allocation fails.