[ 3.8.y.z extended stable ] Patch "ALSA: 6fire: fix DMA issues with URB transfer_buffer usage" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    ALSA: 6fire: fix DMA issues with URB transfer_buffer usage

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.7.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 2ba7c5aa6bba683cd8cf10f8bc55a0b232025685 Mon Sep 17 00:00:00 2001
From: Jussi Kivilinna <jussi.kivilinna at iki.fi>
Date: Tue, 6 Aug 2013 14:53:24 +0300
Subject: ALSA: 6fire: fix DMA issues with URB transfer_buffer usage

commit ddb6b5a964371e8e52e696b2b258bda144c8bd3f upstream.

Patch fixes 6fire not to use stack as URB transfer_buffer. URB buffers need to
be DMA-able, which stack is not. Furthermore, transfer_buffer should not be
allocated as part of larger device structure because DMA coherency issues and
patch fixes this issue too.

Signed-off-by: Jussi Kivilinna <jussi.kivilinna at iki.fi>
Tested-by: Torsten Schenk <torsten.schenk at zoho.com>
Signed-off-by: Takashi Iwai <tiwai at suse.de>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 sound/usb/6fire/comm.c | 38 +++++++++++++++++++++++++++++++++-----
 sound/usb/6fire/comm.h |  2 +-
 2 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/sound/usb/6fire/comm.c b/sound/usb/6fire/comm.c
index 9e6e3ff..23452ee 100644
--- a/sound/usb/6fire/comm.c
+++ b/sound/usb/6fire/comm.c
@@ -110,19 +110,37 @@ static int usb6fire_comm_send_buffer(u8 *buffer, struct usb_device *dev)
 static int usb6fire_comm_write8(struct comm_runtime *rt, u8 request,
 		u8 reg, u8 value)
 {
-	u8 buffer[13]; /* 13: maximum length of message */
+	u8 *buffer;
+	int ret;
+
+	/* 13: maximum length of message */
+	buffer = kmalloc(13, GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;

 	usb6fire_comm_init_buffer(buffer, 0x00, request, reg, value, 0x00);
-	return usb6fire_comm_send_buffer(buffer, rt->chip->dev);
+	ret = usb6fire_comm_send_buffer(buffer, rt->chip->dev);
+
+	kfree(buffer);
+	return ret;
 }

 static int usb6fire_comm_write16(struct comm_runtime *rt, u8 request,
 		u8 reg, u8 vl, u8 vh)
 {
-	u8 buffer[13]; /* 13: maximum length of message */
+	u8 *buffer;
+	int ret;
+
+	/* 13: maximum length of message */
+	buffer = kmalloc(13, GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;

 	usb6fire_comm_init_buffer(buffer, 0x00, request, reg, vl, vh);
-	return usb6fire_comm_send_buffer(buffer, rt->chip->dev);
+	ret = usb6fire_comm_send_buffer(buffer, rt->chip->dev);
+
+	kfree(buffer);
+	return ret;
 }

 int usb6fire_comm_init(struct sfire_chip *chip)
@@ -135,6 +153,12 @@ int usb6fire_comm_init(struct sfire_chip *chip)
 	if (!rt)
 		return -ENOMEM;

+	rt->receiver_buffer = kzalloc(COMM_RECEIVER_BUFSIZE, GFP_KERNEL);
+	if (!rt->receiver_buffer) {
+		kfree(rt);
+		return -ENOMEM;
+	}
+
 	urb = &rt->receiver;
 	rt->serial = 1;
 	rt->chip = chip;
@@ -153,6 +177,7 @@ int usb6fire_comm_init(struct sfire_chip *chip)
 	urb->interval = 1;
 	ret = usb_submit_urb(urb, GFP_KERNEL);
 	if (ret < 0) {
+		kfree(rt->receiver_buffer);
 		kfree(rt);
 		snd_printk(KERN_ERR PREFIX "cannot create comm data receiver.");
 		return ret;
@@ -171,6 +196,9 @@ void usb6fire_comm_abort(struct sfire_chip *chip)

 void usb6fire_comm_destroy(struct sfire_chip *chip)
 {
-	kfree(chip->comm);
+	struct comm_runtime *rt = chip->comm;
+
+	kfree(rt->receiver_buffer);
+	kfree(rt);
 	chip->comm = NULL;
 }
diff --git a/sound/usb/6fire/comm.h b/sound/usb/6fire/comm.h
index 6a0840b..780d5ed 100644
--- a/sound/usb/6fire/comm.h
+++ b/sound/usb/6fire/comm.h
@@ -24,7 +24,7 @@ struct comm_runtime {
 	struct sfire_chip *chip;

 	struct urb receiver;
-	u8 receiver_buffer[COMM_RECEIVER_BUFSIZE];
+	u8 *receiver_buffer;

 	u8 serial; /* urb serial */

--
1.8.1.2