Re: [PATCH v6] can: kvaser_usb: Add support for Kvaser CAN/USB devices

On Thu, Nov 22, 2012 at 04:01:49PM +0100, Olivier Sobrie wrote:

Hi linux-usb folks,

Is there someone who can help me to fix the following errors?

smatch warnings:

+ drivers/net/can/usb/kvaser_usb.c:431 kvaser_usb_send_simple_msg() error: doing
+dma on the stack ((null))
+ drivers/net/can/usb/kvaser_usb.c:1073 kvaser_usb_set_opt_mode() error: doing
+dma on the stack ((null))
+ drivers/net/can/usb/kvaser_usb.c:1174 kvaser_usb_flush_queue() error: doing
+dma on the stack ((null))
+ drivers/net/can/usb/kvaser_usb.c:1384 kvaser_usb_set_bittiming() error: doing
+dma on the stack ((null))

I assume it's due to the buffer I pass to the function usb_bulk_msg()
which is on the stack and can't be.
Do I just have to kmalloc a buffer and give it to the usb_bulk_msg()
function? That's what I understood by reading
"Documentation/DMA-API-HOWTO.txt" section "What memory is DMA'able?"...
and from commit
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=32ec4576c3fb37316b1d11a04b220527822f3f0d

Yes, that is all that is needed.

thanks,

greg k-h