linux-kernel - [PATCH 2/6 v2] [media] vp7045: get rid of on-stack dma buffers

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Message-Id: <1300732426-18958-3-git-send-email-florian@mickler.org>
Date:	Mon, 21 Mar 2011 19:33:42 +0100
From:	Florian Mickler <florian@...kler.org>
To:	mchehab@...radead.org
Cc:	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
	js@...uxtv.org, tskd2@...oo.co.jp, liplianin@...by,
	g.marco@...enet.de, aet@...terburn.org, pb@...uxtv.org,
	mkrufky@...uxtv.org, nick@...k-andrew.net, max@...eto.com,
	janne-dvb@...nau.be, Florian Mickler <florian@...kler.org>
Subject: [PATCH 2/6 v2] [media] vp7045: get rid of on-stack dma buffers

usb_control_msg initiates (and waits for completion of) a dma transfer using
the supplied buffer. That buffer thus has to be seperately allocated on
the heap.

In lib/dma_debug.c the function check_for_stack even warns about it:
	WARNING: at lib/dma-debug.c:866 check_for_stack

Note: This change is tested to compile only, as I don't have the hardware.

Signed-off-by: Florian Mickler <florian@...kler.org>

---
[v2: pulled buffer access under the mutex]

drivers/media/dvb/dvb-usb/vp7045.c |   47 ++++++++++++++++++++++++++----------
 1 files changed, 34 insertions(+), 13 deletions(-)

diff --git a/drivers/media/dvb/dvb-usb/vp7045.c b/drivers/media/dvb/dvb-usb/vp7045.c
index ab0ab3c..3db89e3 100644
--- a/drivers/media/dvb/dvb-usb/vp7045.c
+++ b/drivers/media/dvb/dvb-usb/vp7045.c
@@ -28,9 +28,9 @@ DVB_DEFINE_MOD_OPT_ADAPTER_NR(adapter_nr);
 int vp7045_usb_op(struct dvb_usb_device *d, u8 cmd, u8 *out, int outlen, u8 *in, int inlen, int msec)
 {
 	int ret = 0;
-	u8 inbuf[12] = { 0 }, outbuf[20] = { 0 };
+	u8 *buf = d->priv;
 
-	outbuf[0] = cmd;
+	buf[0] = cmd;
 
 	if (outlen > 19)
 		outlen = 19;
@@ -38,19 +38,21 @@ int vp7045_usb_op(struct dvb_usb_device *d, u8 cmd, u8 *out, int outlen, u8 *in,
 	if (inlen > 11)
 		inlen = 11;
 
+	ret = mutex_lock_interruptible(&d->usb_mutex);
+	if (ret)
+		return ret;
+
 	if (out != NULL && outlen > 0)
-		memcpy(&outbuf[1], out, outlen);
+		memcpy(&buf[1], out, outlen);
 
 	deb_xfer("out buffer: ");
-	debug_dump(outbuf,outlen+1,deb_xfer);
+	debug_dump(buf, outlen+1, deb_xfer);
 
-	if ((ret = mutex_lock_interruptible(&d->usb_mutex)))
-		return ret;
 
 	if (usb_control_msg(d->udev,
 			usb_sndctrlpipe(d->udev,0),
 			TH_COMMAND_OUT, USB_TYPE_VENDOR | USB_DIR_OUT, 0, 0,
-			outbuf, 20, 2000) != 20) {
+			buf, 20, 2000) != 20) {
 		err("USB control message 'out' went wrong.");
 		ret = -EIO;
 		goto unlock;
@@ -61,17 +63,17 @@ int vp7045_usb_op(struct dvb_usb_device *d, u8 cmd, u8 *out, int outlen, u8 *in,
 	if (usb_control_msg(d->udev,
 			usb_rcvctrlpipe(d->udev,0),
 			TH_COMMAND_IN, USB_TYPE_VENDOR | USB_DIR_IN, 0, 0,
-			inbuf, 12, 2000) != 12) {
+			buf, 12, 2000) != 12) {
 		err("USB control message 'in' went wrong.");
 		ret = -EIO;
 		goto unlock;
 	}
 
 	deb_xfer("in buffer: ");
-	debug_dump(inbuf,12,deb_xfer);
+	debug_dump(buf, 12, deb_xfer);
 
 	if (in != NULL && inlen > 0)
-		memcpy(in,&inbuf[1],inlen);
+		memcpy(in, &buf[1], inlen);
 
 unlock:
 	mutex_unlock(&d->usb_mutex);
@@ -222,8 +224,26 @@ static struct dvb_usb_device_properties vp7045_properties;
 static int vp7045_usb_probe(struct usb_interface *intf,
 		const struct usb_device_id *id)
 {
-	return dvb_usb_device_init(intf, &vp7045_properties,
-				   THIS_MODULE, NULL, adapter_nr);
+	struct dvb_usb_device *d;
+	int ret = dvb_usb_device_init(intf, &vp7045_properties,
+				   THIS_MODULE, &d, adapter_nr);
+	if (ret)
+		return ret;
+
+	d->priv = kmalloc(20, GFP_KERNEL);
+	if (!d->priv) {
+		dvb_usb_device_exit(intf);
+		return -ENOMEM;
+	}
+
+	return ret;
+}
+
+static void vp7045_usb_disconnect(struct usb_interface *intf)
+{
+	struct dvb_usb_device *d = usb_get_intfdata(intf);
+	kfree(d->priv);
+	dvb_usb_device_exit(intf);
 }
 
 static struct usb_device_id vp7045_usb_table [] = {
@@ -238,6 +258,7 @@ MODULE_DEVICE_TABLE(usb, vp7045_usb_table);
 static struct dvb_usb_device_properties vp7045_properties = {
 	.usb_ctrl = CYPRESS_FX2,
 	.firmware = "dvb-usb-vp7045-01.fw",
+	.size_of_priv = sizeof(u8 *),
 
 	.num_adapters = 1,
 	.adapter = {
@@ -284,7 +305,7 @@ static struct dvb_usb_device_properties vp7045_properties = {
 static struct usb_driver vp7045_usb_driver = {
 	.name		= "dvb_usb_vp7045",
 	.probe		= vp7045_usb_probe,
-	.disconnect = dvb_usb_device_exit,
+	.disconnect	= vp7045_usb_disconnect,
 	.id_table	= vp7045_usb_table,
 };
 
-- 
1.7.4.1

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