IRQs and memory consistency

On 10.04.2012 19:58, Wink Saville wrote:

Sounds to me like there needs to be a flush of the processor cache
by using memory barriers.

I used a wmb(); right after I set the value I wanted.

I'm guessing that the IRQ is taken on a different thread and possibly
a different processor and the value needs to be flushed. You might
try having devid be an atomic_t and then use atomic_set
and atomic_read so that the "proper" memory barriers are used.

should I use atomic ops instead of a wmb?
The interrupt can't happen until the value is assigned completely in 
one thread. I'm sure.