[openib-general] What context can CM be called from?

[Sean Hefty]

Roland Dreier wrote:
>     Tziporet> Hi, If I remember correctly the verbs of create &
>     Tziporet> destroy AVs should be enabled from interrupt context too
>     Tziporet> since they are not privileged verbs. In VAPI we
>     Tziporet> implemented these verbs in this way and I think it is
>     Tziporet> important to keep it this way.
> 
> Yes, you're correct that the AV verbs are not privileged according to
> the table in chapter 11 of the IB spec.  I'm not sure that this
> requires that they must be available from interrupt context but it is
> reasonable for us to choose the policy that all non-privileged verbs
> may be called from interrupt context.
> 
> Fixing mthca to allow the AH verbs to be callable from interrupt
> context is easy -- the trivial patch is included below.
> 
> I'm not sure if this removes all obstructions to the CM being usable
> from interrupt context.

With this patch, changing the kmalloc in cm_alloc_msg() to use 
GFP_ATOMIC rather than GFP_KERNEL should allow the CM to be usable from 
interrupt context.  Of course, I haven't actually tested this...

I have no objection to this change however.

- Sean