Re: [PATCH v3] staging: gdm724x: Fix DMA from stack

[Amey Narkhede]

On 21/02/10 03:55PM, Greg KH wrote:
> On Wed, Feb 10, 2021 at 07:55:12PM +0530, Amey Narkhede wrote:
> > Stack allocated buffers cannot be used for DMA
> > on all architectures so allocate hci_packet buffer
> > using kmalloc.
> >
> > Signed-off-by: Amey Narkhede <ameynarkhed...@gmail.com>
> > ---
> > Changes in v3:
> >     - Remove superfluous buf pointer
> >     - Reduce size of allocation of hci_packet to match number of
> >     bytes used for DMA
> >
> >  drivers/staging/gdm724x/gdm_usb.c | 10 +++++++---
> >  1 file changed, 7 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/staging/gdm724x/gdm_usb.c 
> > b/drivers/staging/gdm724x/gdm_usb.c
> > index dc4da66c3..80c58a3ef 100644
> > --- a/drivers/staging/gdm724x/gdm_usb.c
> > +++ b/drivers/staging/gdm724x/gdm_usb.c
> > @@ -56,20 +56,24 @@ 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;
> > +   struct hci_packet *hci;
> >     struct usb_device *usbdev = udev->usbdev;
> >     int actual;
> >     int ret = -1;
> >
> > +   hci = kmalloc(5, GFP_KERNEL);
>
> Why "5" and not:
>       hci = kmalloc(sizeof(*hci), GFP_KERNEL);
> ?
>
> thanks,
>
> greg k-h
I really need a cup of coffee :)
I'll send v4

Thanks,
Amey

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