Re: [PATCH] HID: lenovo: Don't use stack variables for DMA buffers

[Jiri Kosina]

On Tue, 29 Mar 2016, Benjamin Tissoires wrote:

> > The lenovo_send_cmd_cptkbd function uses a stack variable to submit
> > commands via hid_hw_raw_request.  Eventually this gets to the
> > usb_hcd_map_urb_for_dma function, which causes a warning to be thrown
> > if the CONFIG_DMA_API_DEBUG option is enabled.
> > 
> > Fix this by allocating a temporary buffer instead.
> > 
> > Reported-by: lejeczek 
> > Signed-off-by: Josh Boyer 
> > ---
> 
> The patch is
> Reviewed-by: Benjamin Tissoires 
> 
> There is just one nitpick that can be solved while committing (or not,
> depending on how Jiri handles it :-P ).

I've nuked the NULL-initialization and applied, thanks!

-- 
Jiri Kosina
SUSE Labs

Re: [PATCH] HID: lenovo: Don't use stack variables for DMA buffers

[Benjamin Tissoires]

On Mar 28 2016 or thereabouts, Josh Boyer wrote:
> The lenovo_send_cmd_cptkbd function uses a stack variable to submit
> commands via hid_hw_raw_request.  Eventually this gets to the
> usb_hcd_map_urb_for_dma function, which causes a warning to be thrown
> if the CONFIG_DMA_API_DEBUG option is enabled.
> 
> Fix this by allocating a temporary buffer instead.
> 
> Reported-by: lejeczek 
> Signed-off-by: Josh Boyer 
> ---

The patch is
Reviewed-by: Benjamin Tissoires 

There is just one nitpick that can be solved while committing (or not,
depending on how Jiri handles it :-P ).

>  drivers/hid/hid-lenovo.c | 16 +---
>  1 file changed, 13 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/hid/hid-lenovo.c b/drivers/hid/hid-lenovo.c
> index 0125e356bd8d..2ba5e8ea66a4 100644
> --- a/drivers/hid/hid-lenovo.c
> +++ b/drivers/hid/hid-lenovo.c
> @@ -184,21 +184,31 @@ static int lenovo_send_cmd_cptkbd(struct hid_device 
> *hdev,
>   unsigned char byte2, unsigned char byte3)
>  {
>   int ret;
> - unsigned char buf[] = {0x18, byte2, byte3};
> + unsigned char *buf = NULL;

No need to initialized buf here :)

Cheers,
Benjamin

> +
> + buf = kzalloc(3, GFP_KERNEL);
> + if (!buf)
> + return -ENOMEM;
> +
> + buf[0] = 0x18;
> + buf[1] = byte2;
> + buf[2] = byte3;
>  
>   switch (hdev->product) {
>   case USB_DEVICE_ID_LENOVO_CUSBKBD:
> - ret = hid_hw_raw_request(hdev, 0x13, buf, sizeof(buf),
> + ret = hid_hw_raw_request(hdev, 0x13, buf, 3,
>   HID_FEATURE_REPORT, HID_REQ_SET_REPORT);
>   break;
>   case USB_DEVICE_ID_LENOVO_CBTKBD:
> - ret = hid_hw_output_report(hdev, buf, sizeof(buf));
> + ret = hid_hw_output_report(hdev, buf, 3);
>   break;
>   default:
>   ret = -EINVAL;
>   break;
>   }
>  
> + kfree(buf);
> +
>   return ret < 0 ? ret : 0; /* BT returns 0, USB returns sizeof(buf) */
>  }
>  
> -- 
> 2.5.5
> 

[PATCH] HID: lenovo: Don't use stack variables for DMA buffers

[Josh Boyer]

The lenovo_send_cmd_cptkbd function uses a stack variable to submit
commands via hid_hw_raw_request.  Eventually this gets to the
usb_hcd_map_urb_for_dma function, which causes a warning to be thrown
if the CONFIG_DMA_API_DEBUG option is enabled.

Fix this by allocating a temporary buffer instead.

Reported-by: lejeczek 
Signed-off-by: Josh Boyer 
---
 drivers/hid/hid-lenovo.c | 16 +---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/hid/hid-lenovo.c b/drivers/hid/hid-lenovo.c
index 0125e356bd8d..2ba5e8ea66a4 100644
--- a/drivers/hid/hid-lenovo.c
+++ b/drivers/hid/hid-lenovo.c
@@ -184,21 +184,31 @@ static int lenovo_send_cmd_cptkbd(struct hid_device *hdev,
unsigned char byte2, unsigned char byte3)
 {
int ret;
-   unsigned char buf[] = {0x18, byte2, byte3};
+   unsigned char *buf = NULL;
+
+   buf = kzalloc(3, GFP_KERNEL);
+   if (!buf)
+   return -ENOMEM;
+
+   buf[0] = 0x18;
+   buf[1] = byte2;
+   buf[2] = byte3;
 
switch (hdev->product) {
case USB_DEVICE_ID_LENOVO_CUSBKBD:
-   ret = hid_hw_raw_request(hdev, 0x13, buf, sizeof(buf),
+   ret = hid_hw_raw_request(hdev, 0x13, buf, 3,
HID_FEATURE_REPORT, HID_REQ_SET_REPORT);
break;
case USB_DEVICE_ID_LENOVO_CBTKBD:
-   ret = hid_hw_output_report(hdev, buf, sizeof(buf));
+   ret = hid_hw_output_report(hdev, buf, 3);
break;
default:
ret = -EINVAL;
break;
}
 
+   kfree(buf);
+
return ret < 0 ? ret : 0; /* BT returns 0, USB returns sizeof(buf) */
 }
 
-- 
2.5.5