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SubjectRe: [PATCH 09/16] [media] au6610: get rid of on-stack dma buffer
On 03/15/2011 10:43 AM, Florian Mickler wrote:
> 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@mickler.org>


This patch did not found from patchwork! Probably skipped due to broken
Cc at my contact. Please resend.

Anyhow, I tested and reviewed it.

Acked-by: Antti Palosaari <crope@iki.fi>
Reviewed-by: Antti Palosaari <crope@iki.fi>
Tested-by: Antti Palosaari <crope@iki.fi>

[1] https://patchwork.kernel.org/project/linux-media/list/

Antti



> ---
> 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;
> }
>


--
http://palosaari.fi/


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