[patch 06/32] ALSA: Fix vunmap and free order in snd_free_sgbuf_pages()

From: Greg KH <gregkh@suse.de>
To: linux-kernel@vger.kernel.org, stable@kernel.org
Cc: Justin Forbes <jmforbes@linuxtx.org>,
	Zwane Mwaikambo <zwane@arm.linux.org.uk>,
	"Theodore Ts'o" <tytso@mit.edu>,
	Randy Dunlap <rdunlap@xenotime.net>,
	Dave Jones <davej@redhat.com>,
	Chuck Wolber <chuckw@quantumlinux.com>,
	Chris Wedgwood <reviews@ml.cw.f00f.org>,
	Michael Krufky <mkrufky@linuxtv.org>,
	Chuck Ebbert <cebbert@redhat.com>,
	Domenico Andreoli <cavokz@gmail.com>, Willy Tarreau <w@1wt.eu>,
	Rodrigo Rubira Branco <rbranco@la.checkpoint.com>,
	Jake Edge <jake@lwn.net>, Eugene Teo <eteo@redhat.com>,
	torvalds@linux-foundation.org, akpm@linux-foundation.org,
	alan@lxorguk.ukuu.org.uk, Jan Beulich <jbeulich@novell.com>,
	Takashi Iwai <tiwai@suse.de>
Subject: [patch 06/32] ALSA: Fix vunmap and free order in snd_free_sgbuf_pages()
Date: Fri, 20 Mar 2009 15:26:17 -0700	[thread overview]
Message-ID: <20090320222709.873921676@mini.kroah.org> (raw)
In-Reply-To: <20090320231037.GA2732@kroah.com>

[-- Attachment #1: alsa-fix-vunmap-and-free-order-in-snd_free_sgbuf_pages.patch --]
[-- Type: text/plain, Size: 1264 bytes --]

2.6.27-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Takashi Iwai <tiwai@suse.de>

commit 6af845e4eb36fb91b322aaf77ec1cab2220a48ad upstream.

In snd_free_sgbuf_pags(), vunmap() is called after releasing the SG
pages, and it causes errors on Xen as Xen manages the pages
differently.  Although no significant errors have been reported on
the actual hardware, this order should be fixed other way round,
first vunmap() then free pages.

Cc: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 sound/core/sgbuf.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/sound/core/sgbuf.c
+++ b/sound/core/sgbuf.c
@@ -38,6 +38,10 @@ int snd_free_sgbuf_pages(struct snd_dma_
 	if (! sgbuf)
 		return -EINVAL;
 
+	if (dmab->area)
+		vunmap(dmab->area);
+	dmab->area = NULL;
+
 	tmpb.dev.type = SNDRV_DMA_TYPE_DEV;
 	tmpb.dev.dev = sgbuf->dev;
 	for (i = 0; i < sgbuf->pages; i++) {
@@ -46,9 +50,6 @@ int snd_free_sgbuf_pages(struct snd_dma_
 		tmpb.bytes = PAGE_SIZE;
 		snd_dma_free_pages(&tmpb);
 	}
-	if (dmab->area)
-		vunmap(dmab->area);
-	dmab->area = NULL;
 
 	kfree(sgbuf->table);
 	kfree(sgbuf->page_table);


