Commit d219face authored Feb 04, 2020 by Krishnamraju Eraparaju Committed by Jason Gunthorpe Feb 11, 2020

RDMA/iw_cxgb4: initiate CLOSE when entering TERM

As per draft-hilland-iwarp-verbs-v1.0, sec 6.2.3, always initiate a CLOSE
when entering into TERM state.

In c4iw_modify_qp(), disconnect operation should only be performed when
the modify_qp call is invoked from ib_core. And all other internal
modify_qp calls(invoked within iw_cxgb4) that needs 'disconnect' should
call c4iw_ep_disconnect() explicitly after modify_qp. Otherwise, deadlocks
like below can occur:

 Call Trace:
  schedule+0x2f/0xa0
  schedule_preempt_disabled+0xa/0x10
  __mutex_lock.isra.5+0x2d0/0x4a0
  c4iw_ep_disconnect+0x39/0x430    => tries to reacquire ep lock again
  c4iw_modify_qp+0x468/0x10d0
  rx_data+0x218/0x570              => acquires ep lock
  process_work+0x5f/0x70
  process_one_work+0x1a7/0x3b0
  worker_thread+0x30/0x390
  kthread+0x112/0x130
  ret_from_fork+0x35/0x40

Fixes: d2c33370 ("RDMA/iw_cxgb4: Always disconnect when QP is transitioning to TERMINATE state")
Link: https://lore.kernel.org/r/20200204091230.7210-1-krishna2@chelsio.com


Signed-off-by: Krishnamraju Eraparaju <krishna2@chelsio.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

parent 10189e8e

drivers/infiniband/hw/cxgb4/cm.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -3036,6 +3036,10 @@ static int terminate(struct c4iw_dev dev, struct sk_buff skb)
		C4IW_QP_ATTR_NEXT_STATE, &attrs, 1);
		}

		/* As per draft-hilland-iwarp-verbs-v1.0, sec 6.2.3,
		* when entering the TERM state the RNIC MUST initiate a CLOSE.
		*/
		c4iw_ep_disconnect(ep, 1, GFP_KERNEL);
		c4iw_put_ep(&ep->com);
		} else
		pr_warn("TERM received tid %u no ep/qp\n", tid);

drivers/infiniband/hw/cxgb4/qp.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -1948,10 +1948,10 @@ int c4iw_modify_qp(struct c4iw_dev rhp, struct c4iw_qp qhp,
		qhp->attr.layer_etype = attrs->layer_etype;
		qhp->attr.ecode = attrs->ecode;
		ep = qhp->ep;
		c4iw_get_ep(&ep->com);
		disconnect = 1;
		if (!internal) {
		c4iw_get_ep(&ep->com);
		terminate = 1;
		disconnect = 1;
		} else {
		terminate = qhp->attr.send_term;
		ret = rdma_fini(rhp, qhp, ep);

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