Re: [PATCH v2] staging: gdm724x: Fix DMA from stack

From: Amey Narkhede
Date: Wed Feb 10 2021 - 04:14:11 EST


On 21/02/10 09:06AM, Greg KH wrote:
> On Wed, Feb 10, 2021 at 01:31:34PM +0530, Amey Narkhede wrote:
> > Stack allocated buffers cannot be used for DMA
> > on all architectures so allocate hci_packet buffer
> > using kzalloc().
> >
> > Signed-off-by: Amey Narkhede <ameynarkhede03@xxxxxxxxx>
> > ---
> > Changes in v2:
> > - Fixed build warning
> > - Fixed memory leak using kfree
> >
> > drivers/staging/gdm724x/gdm_usb.c | 9 +++++++--
> > 1 file changed, 7 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/staging/gdm724x/gdm_usb.c b/drivers/staging/gdm724x/gdm_usb.c
> > index dc4da66c3..c4a9b90c5 100644
> > --- a/drivers/staging/gdm724x/gdm_usb.c
> > +++ b/drivers/staging/gdm724x/gdm_usb.c
> > @@ -56,11 +56,15 @@ static int gdm_usb_recv(void *priv_dev,
> >
> > static int request_mac_address(struct lte_udev *udev)
> > {
> > - u8 buf[16] = {0,};
> > - struct hci_packet *hci = (struct hci_packet *)buf;
> > + u8 *buf;
> > + struct hci_packet *hci;
> > struct usb_device *usbdev = udev->usbdev;
> > int actual;
> > int ret = -1;
> > + buf = kzalloc(16, GFP_KERNEL);
>
> checkpatch did not complain about this?
No. checkpatch shows no errors and warnings.
>
> And why do you need 'buf' anymore now? Why not just allocate hci and
> pass that to the request instead? Saves you an extra cast and an extra
> pointer.
>
> thanks,
>
> greg k-h
Thanks. I'll send v3. I assume now we don't need kzalloc anymore as we initialize
the hci_packet so kmalloc(sizeof(struct hci_packet),..) will do.

Amey

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