Re: Questions regarding CMA

[Jack Morgenstein <jackm-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>]

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.
> 
> > 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
--
To unsubscribe from this list: send the line "unsubscribe linux-rdma" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html