Hi Simon,

Thanks for taking a look.

You are right — xgene_enet_is_bufpool() checks
(id & RING_BUFNUM_MASK) >= 0x20, and
xgene_enet_ring_bufnum() returns the same masked value.
So the condition guarantees that the subtraction cannot
underflow.

This appears to be a false positive from Smatch. I missed checking all the conditions.
Sorry for the inconvenience caused. I will drop this patch.

Thanks for pointing it out.

Regards,
Anas