[openib-general] [PATCH] for-2.6.19 cma: protect against adding device during destruction

[Sean Hefty]

>Does this patch protects against the case where an rdma_cm_id is being
>destructed while address resolution related to the **same** id attaches
>it to a device?
>
>If yes, why does someone destroys this id? is it legal to do so?

Yes - this protects against the user destroying the id while that same id is
being attached to a device.  This is legal.  The user may want to cancel address
resolution by destroying the rdma_cm_id.

The issue is that address resolution is asynchronous, with device attachment
occurring in the address resolution callback handler.  The user isn't aware that
the callback handler has been invoked, and may attempt to destroy the rdma_cm_id
when this occurs.

- Sean