On Wed, 2014-03-05 at 14:12 +0200, Sagi Grimberg wrote: > On 3/5/2014 2:06 AM, Nicholas A. Bellinger wrote: > > On Tue, 2014-03-04 at 17:17 +0200, Sagi Grimberg wrote: > >> On 3/4/2014 2:00 AM, Nicholas A. Bellinger wrote: > >>> From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx> > >>> <SNIP> > >> More on cleanup flow. isert_cma_handler does not handle > >> RDMA_CM_EVENT_TIMEWAIT_EXIT. > >> To be more specific, according to IB spec, when initiating disconnect > >> (rdma_disconnect/ib_send_cm_dreq), > >> one should not destroy a used qp until getting TIMEWAIT_EXIT CM event. > >> We are working on this in iSER initiator. > >> It might lead to "stale connection" CM rejects on future connections > >> (SRP also does not do that). > >> > > <nod>, I noticed that as well during recent debugging. > > > > However, AFAICT the RDMA_CM_EVENT_TIMEWAIT_EVENT doesn't (always) occur > > on the target side after a RDMA_CM_EVENT_DISCONNECTED, and thus far I've > > not been able to ascertain what's different about the shutdown sequence > > that would make this happen, or not happen.. > > > > Any ideas..? > > That's probably because the cm_id is destroyed before you get the event. > There is a specific > timout computation to get this event (see IB spec). If you will attempt > to disconnect while > the link is down (initiator won't receive it and send you disconnect > back), you should be able > to see this event. As I understand, in order to comply the spec, the QP > (and the cm_id afterwards) > should be destroyed only when getting this event and not before. > <nod>, thanks for the additional background. So currently rdma_destroy_qp() + rdma_destroy_id() is being done via isert_connect_release(), which occurs after the final isert_put_conn() happens from either the RDMA_CM_EVENT_DISCONNECTED handler, or within isert_free_conn() in one of the per connection kernel thread contexts via iscsit_close_connection(). If I understand the above correctly, the isert_put_conn() should move from the RDMA_CM_EVENT_DISCONNECTED handler into the TIMEWAIT_EVENT handler, yes..? And it's safe to assume that DISCONNECTED will always occur before TIMEWAIT_EVENT, right..? --nab -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
