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SubjectRe: [PATCH 1/2] iWARP Connection Manager.
Steve Wise wrote:
>>>+int iw_cm_disconnect(struct iw_cm_id *cm_id, int abrupt)
>>>+{
>>>+ struct iwcm_id_private *cm_id_priv;
>>>+ unsigned long flags;
>>>+ int ret = 0;
>>>+
>>>+ cm_id_priv = container_of(cm_id, struct iwcm_id_private, id);
>>>+ /* Wait if we're currently in a connect or accept downcall */
>>>+ wait_event(cm_id_priv->connect_wait,
>>>+ !test_bit(IWCM_F_CONNECT_WAIT, &cm_id_priv->flags));
>>
>>Am I understanding this check correctly? You're checking to see if the user has
>>called iw_cm_disconnect() at the same time that they called iw_cm_connect() or
>>iw_cm_accept(). Are connect / accept blocking, or are you just waiting for an
>>event?
>
>
> The CM must wait for the low level provider to finish a connect() or
> accept() operation before telling the low level provider to disconnect
> via modifying the iwarp QP. Regardless of whether they block, this
> disconnect can happen concurrently with the connect/accept so we need to
> hold the disconnect until the connect/accept completes.
>
>
>>>+EXPORT_SYMBOL(iw_cm_disconnect);
>>>+static void destroy_cm_id(struct iw_cm_id *cm_id)
>>>+{
>>>+ struct iwcm_id_private *cm_id_priv;
>>>+ unsigned long flags;
>>>+ int ret;
>>>+
>>>+ cm_id_priv = container_of(cm_id, struct iwcm_id_private, id);
>>>+ /* Wait if we're currently in a connect or accept downcall. A
>>>+ * listening endpoint should never block here. */
>>>+ wait_event(cm_id_priv->connect_wait,
>>>+ !test_bit(IWCM_F_CONNECT_WAIT, &cm_id_priv->flags));
>>
>>Same question/comment as above.
>>
>
>
> Same answer.

There's a difference between trying to handle the user calling
disconnect/destroy at the same time a call to accept/connect is active, versus
the user calling disconnect/destroy after accept/connect have returned. In the
latter case, I think you're fine. In the first case, this is allowing a user to
call destroy at the same time that they're calling accept/connect.
Additionally, there's no guarantee that the F_CONNECT_WAIT flag has been set by
accept/connect by the time disconnect/destroy tests it.

- Sean
-
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