Re: [PATCH v1 05/12] IB/cm: Share listening CM IDs

Jason Gunthorpe
2015-07-13T17:48:37Z

On Mon, Jun 22, 2015 at 03:42:34PM +0300, Haggai Eran wrote:
> spin_lock_irq(&cm.lock);
> + if (--cm_id_priv->listen_sharecount > 0) {
> + /* The id is still shared. */
> + atomic_dec(&cm_id_priv->refcount);

Nit: This looks very strange not to be cm_deref_id .. Looks OK as is
because we are sure refcount cannot be 0 here?

> @@ -958,8 +988,10 @@ int ib_cm_listen(struct ib_cm_id *cm_id, __be64 service_id, __be64 service_mask,
> }
>
> cm_id->state = IB_CM_LISTEN;
> + ++cm_id_priv->listen_sharecount;
>
> - spin_lock_irqsave(&cm.lock, flags);
> + if (lock)
> + spin_lock_irqsave(&cm.lock, flags);

Hmm, I'd like to see the listen_sharecount consistently locked, so it
should be manipulated only while cm.lock is held..

> if (service_id == IB_CM_ASSIGN_SERVICE_ID) {
> cm_id->service_id = cpu_to_be64(cm.listen_service_id++);
> cm_id->service_mask = ~cpu_to_be64(0);
> @@ -968,18 +1000,98 @@ int ib_cm_listen(struct ib_cm_id *cm_id, __be64 service_id, __be64 service_mask,
> cm_id->service_mask = service_mask;
> }
> cur_cm_id_priv = cm_insert_listen(cm_id_priv);
> - spin_unlock_irqrestore(&cm.lock, flags);
> + if (lock)
> + spin_unlock_irqrestore(&cm.lock, flags);
>
> if (cur_cm_id_priv) {
> cm_id->state = IB_CM_IDLE;
> + --cm_id_priv->listen_sharecount;

Ditto

Otherwise I don't see any other mechanical problems with this. Sean
said he was happy with the idea right?

Reviewed-By: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>

Jason
--
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