Re: [BUG] usb: cdc-wdm: Missing barriers in ad-hoc lockless buffer

[Oliver Neukum]

On 05.03.26 13:28, Gui-Dong Han wrote:

> Specifically, wdm_read() accesses ->length and then ->flags, often
> without holding ->iuspin. Similarly, wdm_in_callback() involves
> multiple accesses to both.
>
> I am indeed nervous about this pattern. Without barriers, changes to
> these associated fields made on one CPU might be observed in a
> completely different order on another CPU.

OK, I rechecked. And indeed it seems to me like setting WDM_OVERFLOW
and WDM_READ could be reordered with respect to each other in
wdm_in_callback() and that must not happen.
What do you think?

	Regards
		Oliver