[PATCH] wcn36xx: use READ_ONCE() to access desc->ctrl

[Daniel Mack]

On Tuesday, April 10, 2018 08:17 PM, Ramon Fried wrote:
> On 10 April 2018 at 20:35, Daniel Mack <daniel at zonque.org> wrote:
>> When accessing shared memory to check for the stat of submitted
>> descriptors, make sure to use READ_ONCE(). This will guarantee the
>> compiler treats these memory locations as volatile and doesn't apply
>> any caching.
>
> The structure that is tested is not shared memory. It's accessed only
> by the apps processor.

Hmm? ctl->desc is of type struct wcn36xx_dxe_desc, which is packed and
shared with the firmware. The WCN36xx_DXE_CTRL_VLD bit in ctrl bitfield
is set by the firmware when a frame is valid, and before asserting the
RX interrupt. So the host CPU must treat it as volatile and expect it to
change.

Am I reading this wrong?


Thanks,
Daniel