RDMA/cxgb4: Fix endpoint mutex deadlocks

In cases where the cm calls c4iw_modify_rc_qp() with the endpoint
mutex held, they must be called with internal == 1.  rx_data() and
process_mpa_reply() are not doing this.  This causes a deadlock
because c4iw_modify_rc_qp() might call c4iw_ep_disconnect() in some
!internal cases, and c4iw_ep_disconnect() acquires the endpoint mutex.
The design was intended to only do the disconnect for !internal calls.

Change rx_data(), FPDU_MODE case, to call c4iw_modify_rc_qp() with
internal == 1, and then disconnect only after releasing the mutex.

Change process_mpa_reply() to call c4iw_modify_rc_qp(TERMINATE) with
internal == 1 and set a new attr flag telling it to send a TERMINATE
message.  Previously this was implied by !internal.

Change process_mpa_reply() to return whether the caller should
disconnect after releasing the endpoint mutex.  Now rx_data() will do
the disconnect in the cases where process_mpa_reply() wants to
disconnect after the TERMINATE is sent.

Change c4iw_modify_rc_qp() RTS->TERM to only disconnect if !internal,
and to send a TERMINATE message if attrs->send_term is 1.

Change abort_connection() to not aquire the ep mutex for setting the
state, and make all calls to abort_connection() do so with the mutex
held.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

3 files changed, 26 insertions, 15 deletions

diff --git a/drivers/infiniband/hw/cxgb4/cm.c b/drivers/infiniband/hw/cxgb4/cm.c
index 185452a..f9b04bc 100644
--- a/drivers/infiniband/hw/cxgb4/cm.c
+++ b/drivers/infiniband/hw/cxgb4/cm.c
@@ -996,7 +996,7 @@ static void close_complete_upcall(struct c4iw_ep *ep, int status)
 static int abort_connection(struct c4iw_ep *ep, struct sk_buff *skb, gfp_t gfp)
 {
 	PDBG("%s ep %p tid %u\n", __func__, ep, ep->hwtid);
-	state_set(&ep->com, ABORTING);
+	__state_set(&ep->com, ABORTING);
 	set_bit(ABORT_CONN, &ep->com.history);
 	return send_abort(ep, skb, gfp);
 }
@@ -1154,7 +1154,7 @@ static int update_rx_credits(struct c4iw_ep *ep, u32 credits)
 	return credits;
 }
 
-static void process_mpa_reply(struct c4iw_ep *ep, struct sk_buff *skb)
+static int process_mpa_reply(struct c4iw_ep *ep, struct sk_buff *skb)
 {
 	struct mpa_message *mpa;
 	struct mpa_v2_conn_params *mpa_v2_params;
@@ -1164,6 +1164,7 @@ static void process_mpa_reply(struct c4iw_ep *ep, struct sk_buff *skb)
 	struct c4iw_qp_attributes attrs;
 	enum c4iw_qp_attr_mask mask;
 	int err;
+	int disconnect = 0;
 
 	PDBG("%s ep %p tid %u\n", __func__, ep, ep->hwtid);
 
@@ -1173,7 +1174,7 @@ static void process_mpa_reply(struct c4iw_ep *ep, struct sk_buff *skb)
 	 * will abort the connection.
 	 */
 	if (stop_ep_timer(ep))
-		return;
+		return 0;
 
 	/*
 	 * If we get more than the supported amount of private data
@@ -1195,7 +1196,7 @@ static void process_mpa_reply(struct c4iw_ep *ep, struct sk_buff *skb)
 	 * if we don't even have the mpa message, then bail.
 	 */
 	if (ep->mpa_pkt_len < sizeof(*mpa))
-		return;
+		return 0;
 	mpa = (struct mpa_message *) ep->mpa_pkt;
 
 	/* Validate MPA header. */
@@ -1235,7 +1236,7 @@ static void process_mpa_reply(struct c4iw_ep *ep, struct sk_buff *skb)
 	 * We'll continue process when more data arrives.
 	 */
 	if (ep->mpa_pkt_len < (sizeof(*mpa) + plen))
-		return;
+		return 0;
 
 	if (mpa->flags & MPA_REJECT) {
 		err = -ECONNREFUSED;
@@ -1337,9 +1338,11 @@ static void process_mpa_reply(struct c4iw_ep *ep, struct sk_buff *skb)
 		attrs.layer_etype = LAYER_MPA | DDP_LLP;
 		attrs.ecode = MPA_NOMATCH_RTR;
 		attrs.next_state = C4IW_QP_STATE_TERMINATE;
+		attrs.send_term = 1;
 		err = c4iw_modify_qp(ep->com.qp->rhp, ep->com.qp,
-				C4IW_QP_ATTR_NEXT_STATE, &attrs, 0);
+				C4IW_QP_ATTR_NEXT_STATE, &attrs, 1);
 		err = -ENOMEM;
+		disconnect = 1;
 		goto out;
 	}
 
@@ -1355,9 +1358,11 @@ static void process_mpa_reply(struct c4iw_ep *ep, struct sk_buff *skb)
 		attrs.layer_etype = LAYER_MPA | DDP_LLP;
 		attrs.ecode = MPA_INSUFF_IRD;
 		attrs.next_state = C4IW_QP_STATE_TERMINATE;
+		attrs.send_term = 1;
 		err = c4iw_modify_qp(ep->com.qp->rhp, ep->com.qp,
-				C4IW_QP_ATTR_NEXT_STATE, &attrs, 0);
+				C4IW_QP_ATTR_NEXT_STATE, &attrs, 1);
 		err = -ENOMEM;
+		disconnect = 1;
 		goto out;
 	}
 	goto out;
@@ -1366,7 +1371,7 @@ err:
 	send_abort(ep, skb, GFP_KERNEL);
 out:
 	connect_reply_upcall(ep, err);
-	return;
+	return disconnect;
 }
 
 static void process_mpa_request(struct c4iw_ep *ep, struct sk_buff *skb)
@@ -1524,6 +1529,7 @@ static int rx_data(struct c4iw_dev *dev, struct sk_buff *skb)
 	unsigned int tid = GET_TID(hdr);
 	struct tid_info *t = dev->rdev.lldi.tids;
 	__u8 status = hdr->status;
+	int disconnect = 0;
 
 	ep = lookup_tid(t, tid);
 	if (!ep)
@@ -1539,7 +1545,7 @@ static int rx_data(struct c4iw_dev *dev, struct sk_buff *skb)
 	switch (ep->com.state) {
 	case MPA_REQ_SENT:
 		ep->rcv_seq += dlen;
-		process_mpa_reply(ep, skb);
+		disconnect = process_mpa_reply(ep, skb);
 		break;
 	case MPA_REQ_WAIT:
 		ep->rcv_seq += dlen;
@@ -1555,13 +1561,16 @@ static int rx_data(struct c4iw_dev *dev, struct sk_buff *skb)
 			       ep->com.state, ep->hwtid, status);
 		attrs.next_state = C4IW_QP_STATE_TERMINATE;
 		c4iw_modify_qp(ep->com.qp->rhp, ep->com.qp,
-			       C4IW_QP_ATTR_NEXT_STATE, &attrs, 0);
+			       C4IW_QP_ATTR_NEXT_STATE, &attrs, 1);
+		disconnect = 1;
 		break;
 	}
 	default:
 		break;
 	}
 	mutex_unlock(&ep->com.mutex);
+	if (disconnect)
+		c4iw_ep_disconnect(ep, 0, GFP_KERNEL);
 	return 0;
 }
 
@@ -3482,9 +3491,9 @@ static void process_timeout(struct c4iw_ep *ep)
 			__func__, ep, ep->hwtid, ep->com.state);
 		abort = 0;
 	}
-	mutex_unlock(&ep->com.mutex);
 	if (abort)
 		abort_connection(ep, NULL, GFP_KERNEL);
+	mutex_unlock(&ep->com.mutex);
 	c4iw_put_ep(&ep->com);
 }
 
diff --git a/drivers/infiniband/hw/cxgb4/iw_cxgb4.h b/drivers/infiniband/hw/cxgb4/iw_cxgb4.h
index 7b8c580..7474b49 100644
--- a/drivers/infiniband/hw/cxgb4/iw_cxgb4.h
+++ b/drivers/infiniband/hw/cxgb4/iw_cxgb4.h
@@ -435,6 +435,7 @@ struct c4iw_qp_attributes {
 	u8 ecode;
 	u16 sq_db_inc;
 	u16 rq_db_inc;
+	u8 send_term;
 };
 
 struct c4iw_qp {
diff --git a/drivers/infiniband/hw/cxgb4/qp.c b/drivers/infiniband/hw/cxgb4/qp.c
index 7b5114c..f18ef34 100644
--- a/drivers/infiniband/hw/cxgb4/qp.c
+++ b/drivers/infiniband/hw/cxgb4/qp.c
@@ -1388,11 +1388,12 @@ 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;
-			disconnect = 1;
-			c4iw_get_ep(&qhp->ep->com);
-			if (!internal)
+			if (!internal) {
+				c4iw_get_ep(&qhp->ep->com);
 				terminate = 1;
-			else {
+				disconnect = 1;
+			} else {
+				terminate = qhp->attr.send_term;
 				ret = rdma_fini(rhp, qhp, ep);
 				if (ret)
 					goto err;