On Fri, Feb 22, 2013 at 07:58:35PM +0100, walter harms wrote:
>
>
> Am 22.02.2013 19:07, schrieb Kumar Amit Mehta:
> > fix for instances of DMA buffer on stack(being passed to usb_control_msg)
> > for
> > the USB-DUXfast Board driver.
> >
> > Signed-off-by: Kumar Amit Mehta <gmate.a...@gmail.com>
> > ---
> > drivers/staging/comedi/drivers/usbduxfast.c | 30
> > ++++++++++++++++-----------
> > 1 file changed, 18 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/staging/comedi/drivers/usbduxfast.c
> > b/drivers/staging/comedi/drivers/usbduxfast.c
> > index 4bf5dd0..1ba0e3d 100644
> > --- a/drivers/staging/comedi/drivers/usbduxfast.c
> > +++ b/drivers/staging/comedi/drivers/usbduxfast.c
> > @@ -436,10 +436,14 @@ static void usbduxfastsub_ai_Irq(struct urb *urb)
> > static int usbduxfastsub_start(struct usbduxfastsub_s *udfs)
> > {
> > int ret;
> > - unsigned char local_transfer_buffer[16];
> > + unsigned char *local_transfer_buffer;
> > +
> > + local_transfer_buffer = kmalloc(1, GFP_KERNEL);
> > + if (!local_transfer_buffer)
> > + return -ENOMEM;
> >
> > /* 7f92 to zero */
> > - local_transfer_buffer[0] = 0;
> > + *local_transfer_buffer = 0;
> > /* bRequest, "Firmware" */
> > ret = usb_control_msg(udfs->usbdev, usb_sndctrlpipe(udfs->usbdev, 0),
> > USBDUXFASTSUB_FIRMWARE,
> > @@ -450,22 +454,25 @@ static int usbduxfastsub_start(struct usbduxfastsub_s
> > *udfs)
> > local_transfer_buffer,
> > 1, /* Length */
> > EZTIMEOUT); /* Timeout */
> > - if (ret < 0) {
> > + if (ret < 0)
> > dev_err(&udfs->interface->dev,
> > "control msg failed (start)\n");
> > - return ret;
> > - }
> >
> > - return 0;
> > + kfree(local_transfer_buffer);
> > + return ret;
> > }
> >
> > static int usbduxfastsub_stop(struct usbduxfastsub_s *udfs)
> > {
> > int ret;
> > - unsigned char local_transfer_buffer[16];
> > + unsigned char *local_transfer_buffer;
> > +
> > + local_transfer_buffer = kmalloc(1, GFP_KERNEL);
> > + if (!local_transfer_buffer)
> > + return -ENOMEM;
> >
> > /* 7f92 to one */
> > - local_transfer_buffer[0] = 1;
> > + *local_transfer_buffer = 1;
> > /* bRequest, "Firmware" */
> > ret = usb_control_msg(udfs->usbdev, usb_sndctrlpipe(udfs->usbdev, 0),
> > USBDUXFASTSUB_FIRMWARE,
> > @@ -474,13 +481,12 @@ static int usbduxfastsub_stop(struct usbduxfastsub_s
> > *udfs)
> > 0x0000, /* Index */
> > local_transfer_buffer, 1, /* Length */
> > EZTIMEOUT); /* Timeout */
> > - if (ret < 0) {
> > + if (ret < 0)
> > dev_err(&udfs->interface->dev,
> > "control msg failed (stop)\n");
> > - return ret;
> > - }
> >
> > - return 0;
> > + kfree(local_transfer_buffer);
> > + return ret;
> > }
> >
> > static int usbduxfastsub_upload(struct usbduxfastsub_s *udfs,
>
> mmh, it seems a bit overheat to alloc 1 byte.
> Could one of the driver maintainers please comment
> is that realy need ?
Yes it is needed.
> or is it possible to pass one byte
> in a register ? (aka char/int) without allocating ?
Nope, the USB host controllers must be able to DMA to this memory
location, so you have to allocate it dynamically, sorry.
thanks,
greg k-h
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