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SubjectRe: [PATCH 12/16] [media] lmedm04: get rid of on-stack dma buffers
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The patch failed for the following reason.

On Tue, 2011-03-15 at 09:43 +0100, 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>
> ---
> drivers/media/dvb/dvb-usb/lmedm04.c | 16 +++++++++++++---
> 1 files changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/media/dvb/dvb-usb/lmedm04.c b/drivers/media/dvb/dvb-usb/lmedm04.c
> index 0a3e88f..bec5439 100644
> --- a/drivers/media/dvb/dvb-usb/lmedm04.c
> +++ b/drivers/media/dvb/dvb-usb/lmedm04.c
> @@ -314,12 +314,17 @@ static int lme2510_int_read(struct dvb_usb_adapter *adap)
> static int lme2510_return_status(struct usb_device *dev)
> {
> int ret = 0;
> - u8 data[10] = {0};
> + u8 *data;
> +
> + data = kzalloc(10, GFP_KERNEL);
> + if (!data)
> + return -ENOMEM;
>
> ret |= usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
> 0x06, 0x80, 0x0302, 0x00, data, 0x0006, 200);
> info("Firmware Status: %x (%x)", ret , data[2]);
>
> + kfree(data);
> return (ret < 0) ? -ENODEV : data[2];

data has been killed off when we need the buffer contents.
changing to the following fixed.

ret = (ret < 0) ? -ENODEV : data[2];

kfree(data);

return ret;


> @@ -603,7 +608,7 @@ static int lme2510_download_firmware(struct usb_device *dev,
> const struct firmware *fw)
> {
> int ret = 0;
> - u8 data[512] = {0};
> + u8 *data;
> u16 j, wlen, len_in, start, end;
> u8 packet_size, dlen, i;
> u8 *fw_data;
> @@ -611,6 +616,11 @@ static int lme2510_download_firmware(struct usb_device *dev,
> packet_size = 0x31;
> len_in = 1;
>
> + data = kzalloc(512, GFP_KERNEL);
> + if (!data) {
> + info("FRM Could not start Firmware Download (Buffer allocation failed)");

Longer than 80 characters,

> + return -ENOMEM;
> + }
>
> info("FRM Starting Firmware Download");
>
> @@ -654,7 +664,7 @@ static int lme2510_download_firmware(struct usb_device *dev,
> else
> info("FRM Firmware Download Completed - Resetting Device");
>
> -
> + kfree(data);
> return (ret < 0) ? -ENODEV : 0;
> }
>

Otherwise the patch as corrected has been put on test. No initial
problems have been encountered.

Regards

Malcolm





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