[openib-general] [PATCH] Optimize cma_process_remove()

[Sean Hefty]

Krishna Kumar2 wrote:
>         mutex_lock(&lock);
>         while (!list_empty(&cma_dev->id_list)) {
>                 id_priv = list_entry(cma_dev->id_list.next,
>                                      struct rdma_id_private, list);
> 
>                 if (cma_internal_listen(id_priv)) {
>                         cma_destroy_listen(id_priv);
>                 } else {
>                         atomic_inc(&id_priv->refcount);
>                         list_del(&id_priv->list);
>                         list_add_tail(&id_priv->list, &remove_list);
>                 }
>         }
>         mutex_unlock(&lock);
> 
>         list_for_each_entry_safe(id_priv, tmp, &remove_list, list) {
>                 ret = cma_remove_id_dev(id_priv);
>                 cma_deref_id(id_priv);
>                 if (ret)
>                         rdma_destroy_id(&id_priv->id);
>         }

I believe that this has the same issue.  If a user tries to destroy an 
rdma_cm_id, it will remove itself from the "device list".  (This is why the ID's 
are moved to a new list, so that the removal still works.)  In the code above, 
destroy thread(s) will remove ID(s) from the remove_list while we're trying to 
walk it.

- Sean