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Subject[PATCH 3/5] [media] au6610: get rid of on-stack dma buffer
Date
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

Signed-off-by: Florian Mickler <florian@mickler.org>
Acked-by: Antti Palosaari <crope@iki.fi>
Reviewed-by: Antti Palosaari <crope@iki.fi>
Tested-by: Antti Palosaari <crope@iki.fi>
---
drivers/media/dvb/dvb-usb/au6610.c | 22 ++++++++++++++++------
1 files changed, 16 insertions(+), 6 deletions(-)
diff --git a/drivers/media/dvb/dvb-usb/au6610.c b/drivers/media/dvb/dvb-usb/au6610.c
index eb34cc3..2351077 100644
--- a/drivers/media/dvb/dvb-usb/au6610.c
+++ b/drivers/media/dvb/dvb-usb/au6610.c
@@ -33,8 +33,16 @@ static int au6610_usb_msg(struct dvb_usb_device *d, u8 operation, u8 addr,
{
int ret;
u16 index;
- u8 usb_buf[6]; /* enough for all known requests,
- read returns 5 and write 6 bytes */
+ u8 *usb_buf;
+
+ /*
+ * allocate enough for all known requests,
+ * read returns 5 and write 6 bytes
+ */
+ usb_buf = kmalloc(6, GFP_KERNEL);
+ if (!usb_buf)
+ return -ENOMEM;
+
switch (wlen) {
case 1:
index = wbuf[0] << 8;
@@ -45,14 +53,15 @@ static int au6610_usb_msg(struct dvb_usb_device *d, u8 operation, u8 addr,
break;
default:
warn("wlen = %x, aborting.", wlen);
- return -EINVAL;
+ ret = -EINVAL;
+ goto error;
}

ret = usb_control_msg(d->udev, usb_rcvctrlpipe(d->udev, 0), operation,
USB_TYPE_VENDOR|USB_DIR_IN, addr << 1, index,
- usb_buf, sizeof(usb_buf), AU6610_USB_TIMEOUT);
+ usb_buf, 6, AU6610_USB_TIMEOUT);
if (ret < 0)
- return ret;
+ goto error;

switch (operation) {
case AU6610_REQ_I2C_READ:
@@ -60,7 +69,8 @@ static int au6610_usb_msg(struct dvb_usb_device *d, u8 operation, u8 addr,
/* requested value is always 5th byte in buffer */
rbuf[0] = usb_buf[4];
}
-
+error:
+ kfree(usb_buf);
return ret;
}

--
1.7.4.1


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