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 <flor...@mickler.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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