Re: [PATCH 19/26] nova-t-usb2: don't do DMA on stack
From: Patrick Boettcher
Date: Mon Oct 10 2016 - 02:35:56 EST
On Fri, 7 Oct 2016 14:24:29 -0300
Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx> wrote:
> The USB control messages require DMA to work. We cannot pass
> a stack-allocated buffer, as it is not warranted that the
> stack would be into a DMA enabled area.
>
> Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx>
> ---
> drivers/media/usb/dvb-usb/nova-t-usb2.c | 18 +++++++++++++-----
> 1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/media/usb/dvb-usb/nova-t-usb2.c
> b/drivers/media/usb/dvb-usb/nova-t-usb2.c index
> fc7569e2728d..26d7188a1163 100644 ---
> a/drivers/media/usb/dvb-usb/nova-t-usb2.c +++
> b/drivers/media/usb/dvb-usb/nova-t-usb2.c @@ -74,22 +74,29 @@ static
> struct rc_map_table rc_map_haupp_table[] = { */
> static int nova_t_rc_query(struct dvb_usb_device *d, u32 *event, int
> *state) {
> - u8 key[5],cmd[2] = { DIBUSB_REQ_POLL_REMOTE, 0x35 },
> data,toggle,custom;
> + u8 *buf, data, toggle, custom;
> u16 raw;
> int i;
> struct dibusb_device_state *st = d->priv;
>
> - dvb_usb_generic_rw(d,cmd,2,key,5,0);
> + buf = kmalloc(5, GFP_KERNEL);
> + if (!buf)
> + return -ENOMEM;
> +
> + buf[0] = DIBUSB_REQ_POLL_REMOTE;
> + buf[1] = 0x35;
> + dvb_usb_generic_rw(d, buf, 2, buf, 5, 0);
>
> *state = REMOTE_NO_KEY_PRESSED;
> - switch (key[0]) {
> + switch (buf[0]) {
> case DIBUSB_RC_HAUPPAUGE_KEY_PRESSED:
> - raw = ((key[1] << 8) | key[2]) >> 3;
> + raw = ((buf[1] << 8) | buf[2]) >> 3;
> toggle = !!(raw & 0x800);
> data = raw & 0x3f;
> custom = (raw >> 6) & 0x1f;
>
> - deb_rc("raw key code 0x%02x, 0x%02x, 0x%02x
> to c: %02x d: %02x toggle:
> %d\n",key[1],key[2],key[3],custom,data,toggle);
> + deb_rc("raw key code 0x%02x, 0x%02x, 0x%02x
> to c: %02x d: %02x toggle: %d\n",
> + buf[1], buf[2], buf[3], custom, data,
> toggle);
> for (i = 0; i <
> ARRAY_SIZE(rc_map_haupp_table); i++) { if
> (rc5_data(&rc_map_haupp_table[i]) == data && @@ -117,6 +124,7 @@
> static int nova_t_rc_query(struct dvb_usb_device *d, u32 *event, int
> *state) break; }
>
> + kfree(buf);
> return 0;
> }
>
Reviewed-By: Patrick Boettcher <patrick.boettcher@xxxxxxxxx>