Re: Questions regarding CMA

On Thursday 14 July 2011 20:46, Hefty, Sean wrote:

Although it's a minor performance gain, I'm leaning towards keeping id_priv->cm_id.ib = NULL on failure, either by resetting it or using a local variable.  cma_has_cm_dev() can then be replaced by checking id_priv->cm_id.ib for non-NULL, and checks for IS_ERR(id_priv->cm_id.ib) are removed.

quoted

Please consider the patch below as a starting point (I did not touch the iwarp
code).
Please let me know (ASAP) what you think.
(I still leave a window here where id_priv->cm_id.ib is ERR. Is this a
problem?
 Would it be better to use a local variable instead of id_priv->cm_id.ib, and
 only assign to id_priv->cm_id.ib when all the error checks have passed?
 This would leave a window where a successful cm_id creation is not
immediately assigned
 to the CMA object -- would this be a problem?).

Without adding more synchronization, we need to ensure that id_priv->cm_id.ib is set before a user can receive any callbacks.
This restricts our use of a local variable to the create_cm_id calls only.
See cma_connect_iw() for an example of using this approach.  

Agreed.  That way we never have to test for IS_ERR. I'll send a patch.

-Jack
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