IB/mthca: Fix RESET to ERROR transition

According to the IB spec, a QP can be moved from RESET to the ERROR 
state, but mthca firmware does not support this and returns an error if 
we try.  Work around this FW limitation by moving the QP from RESET to
INIT with dummy parameters and then transitioning from INIT to ERROR.

Signed-off-by: Michael S. Tsirkin <mst@dev.mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/hw/mthca/mthca_qp.c

@@ -295,7 +295,7 @@ static int to_mthca_st(int transport)
 	}
 }
 
-static void store_attrs(struct mthca_sqp *sqp, struct ib_qp_attr *attr,
+static void store_attrs(struct mthca_sqp *sqp, const struct ib_qp_attr *attr,
 			int attr_mask)
 {
 	if (attr_mask & IB_QP_PKEY_INDEX)
@@ -327,7 +327,7 @@ static void init_port(struct mthca_dev *dev, int port)
 		mthca_warn(dev, "INIT_IB returned status %02x.\n", status);
 }
 
-static __be32 get_hw_access_flags(struct mthca_qp *qp, struct ib_qp_attr *attr,
+static __be32 get_hw_access_flags(struct mthca_qp *qp, const struct ib_qp_attr *attr,
 				  int attr_mask)
 {
 	u8 dest_rd_atomic;
@@ -510,7 +510,7 @@ out:
 	return err;
 }
 
-static int mthca_path_set(struct mthca_dev *dev, struct ib_ah_attr *ah,
+static int mthca_path_set(struct mthca_dev *dev, const struct ib_ah_attr *ah,
 			  struct mthca_qp_path *path, u8 port)
 {
 	path->g_mylmc     = ah->src_path_bits & 0x7f;
@@ -538,12 +538,12 @@ static int mthca_path_set(struct mthca_dev *dev, struct ib_ah_attr *ah,
 	return 0;
 }
 
-int mthca_modify_qp(struct ib_qp *ibqp, struct ib_qp_attr *attr, int attr_mask,
-		    struct ib_udata *udata)
+static int __mthca_modify_qp(struct ib_qp *ibqp,
+			     const struct ib_qp_attr *attr, int attr_mask,
+			     enum ib_qp_state cur_state, enum ib_qp_state new_state)
 {
 	struct mthca_dev *dev = to_mdev(ibqp->device);
 	struct mthca_qp *qp = to_mqp(ibqp);
-	enum ib_qp_state cur_state, new_state;
 	struct mthca_mailbox *mailbox;
 	struct mthca_qp_param *qp_param;
 	struct mthca_qp_context *qp_context;
@@ -551,60 +551,6 @@ int mthca_modify_qp(struct ib_qp *ibqp, struct ib_qp_attr *attr, int attr_mask,
 	u8 status;
 	int err = -EINVAL;
 
-	mutex_lock(&qp->mutex);
-
-	if (attr_mask & IB_QP_CUR_STATE) {
-		cur_state = attr->cur_qp_state;
-	} else {
-		spin_lock_irq(&qp->sq.lock);
-		spin_lock(&qp->rq.lock);
-		cur_state = qp->state;
-		spin_unlock(&qp->rq.lock);
-		spin_unlock_irq(&qp->sq.lock);
-	}
-
-	new_state = attr_mask & IB_QP_STATE ? attr->qp_state : cur_state;
-
-	if (!ib_modify_qp_is_ok(cur_state, new_state, ibqp->qp_type, attr_mask)) {
-		mthca_dbg(dev, "Bad QP transition (transport %d) "
-			  "%d->%d with attr 0x%08x\n",
-			  qp->transport, cur_state, new_state,
-			  attr_mask);
-		goto out;
-	}
-
-	if (cur_state == new_state && cur_state == IB_QPS_RESET) {
-		err = 0;
-		goto out;
-	}
-
-	if ((attr_mask & IB_QP_PKEY_INDEX) &&
-	     attr->pkey_index >= dev->limits.pkey_table_len) {
-		mthca_dbg(dev, "P_Key index (%u) too large. max is %d\n",
-			  attr->pkey_index, dev->limits.pkey_table_len-1);
-		goto out;
-	}
-
-	if ((attr_mask & IB_QP_PORT) &&
-	    (attr->port_num == 0 || attr->port_num > dev->limits.num_ports)) {
-		mthca_dbg(dev, "Port number (%u) is invalid\n", attr->port_num);
-		goto out;
-	}
-
-	if (attr_mask & IB_QP_MAX_QP_RD_ATOMIC &&
-	    attr->max_rd_atomic > dev->limits.max_qp_init_rdma) {
-		mthca_dbg(dev, "Max rdma_atomic as initiator %u too large (max is %d)\n",
-			  attr->max_rd_atomic, dev->limits.max_qp_init_rdma);
-		goto out;
-	}
-
-	if (attr_mask & IB_QP_MAX_DEST_RD_ATOMIC &&
-	    attr->max_dest_rd_atomic > 1 << dev->qp_table.rdb_shift) {
-		mthca_dbg(dev, "Max rdma_atomic as responder %u too large (max %d)\n",
-			  attr->max_dest_rd_atomic, 1 << dev->qp_table.rdb_shift);
-		goto out;
-	}
-
 	mailbox = mthca_alloc_mailbox(dev, GFP_KERNEL);
 	if (IS_ERR(mailbox)) {
 		err = PTR_ERR(mailbox);
@@ -891,6 +837,98 @@ int mthca_modify_qp(struct ib_qp *ibqp, struct ib_qp_attr *attr, int attr_mask,
 
 out_mailbox:
 	mthca_free_mailbox(dev, mailbox);
+out:
+	return err;
+}
+
+static const struct ib_qp_attr dummy_init_attr = { .port_num = 1 };
+static const int dummy_init_attr_mask[] = {
+	[IB_QPT_UD]  = (IB_QP_PKEY_INDEX		|
+			IB_QP_PORT			|
+			IB_QP_QKEY),
+	[IB_QPT_UC]  = (IB_QP_PKEY_INDEX		|
+			IB_QP_PORT			|
+			IB_QP_ACCESS_FLAGS),
+	[IB_QPT_RC]  = (IB_QP_PKEY_INDEX		|
+			IB_QP_PORT			|
+			IB_QP_ACCESS_FLAGS),
+	[IB_QPT_SMI] = (IB_QP_PKEY_INDEX		|
+			IB_QP_QKEY),
+	[IB_QPT_GSI] = (IB_QP_PKEY_INDEX		|
+			IB_QP_QKEY),
+};
+
+int mthca_modify_qp(struct ib_qp *ibqp, struct ib_qp_attr *attr, int attr_mask,
+		    struct ib_udata *udata)
+{
+	struct mthca_dev *dev = to_mdev(ibqp->device);
+	struct mthca_qp *qp = to_mqp(ibqp);
+	enum ib_qp_state cur_state, new_state;
+	int err = -EINVAL;
+
+	mutex_lock(&qp->mutex);
+	if (attr_mask & IB_QP_CUR_STATE) {
+		cur_state = attr->cur_qp_state;
+	} else {
+		spin_lock_irq(&qp->sq.lock);
+		spin_lock(&qp->rq.lock);
+		cur_state = qp->state;
+		spin_unlock(&qp->rq.lock);
+		spin_unlock_irq(&qp->sq.lock);
+	}
+
+	new_state = attr_mask & IB_QP_STATE ? attr->qp_state : cur_state;
+
+	if (!ib_modify_qp_is_ok(cur_state, new_state, ibqp->qp_type, attr_mask)) {
+		mthca_dbg(dev, "Bad QP transition (transport %d) "
+			  "%d->%d with attr 0x%08x\n",
+			  qp->transport, cur_state, new_state,
+			  attr_mask);
+		goto out;
+	}
+
+	if ((attr_mask & IB_QP_PKEY_INDEX) &&
+	     attr->pkey_index >= dev->limits.pkey_table_len) {
+		mthca_dbg(dev, "P_Key index (%u) too large. max is %d\n",
+			  attr->pkey_index, dev->limits.pkey_table_len-1);
+		goto out;
+	}
+
+	if ((attr_mask & IB_QP_PORT) &&
+	    (attr->port_num == 0 || attr->port_num > dev->limits.num_ports)) {
+		mthca_dbg(dev, "Port number (%u) is invalid\n", attr->port_num);
+		goto out;
+	}
+
+	if (attr_mask & IB_QP_MAX_QP_RD_ATOMIC &&
+	    attr->max_rd_atomic > dev->limits.max_qp_init_rdma) {
+		mthca_dbg(dev, "Max rdma_atomic as initiator %u too large (max is %d)\n",
+			  attr->max_rd_atomic, dev->limits.max_qp_init_rdma);
+		goto out;
+	}
+
+	if (attr_mask & IB_QP_MAX_DEST_RD_ATOMIC &&
+	    attr->max_dest_rd_atomic > 1 << dev->qp_table.rdb_shift) {
+		mthca_dbg(dev, "Max rdma_atomic as responder %u too large (max %d)\n",
+			  attr->max_dest_rd_atomic, 1 << dev->qp_table.rdb_shift);
+		goto out;
+	}
+
+	if (cur_state == new_state && cur_state == IB_QPS_RESET) {
+		err = 0;
+		goto out;
+	}
+
+	if (cur_state == IB_QPS_RESET && new_state == IB_QPS_ERR) {
+		err = __mthca_modify_qp(ibqp, &dummy_init_attr,
+					dummy_init_attr_mask[ibqp->qp_type],
+					IB_QPS_RESET, IB_QPS_INIT);
+		if (err)
+			goto out;
+		cur_state = IB_QPS_INIT;
+	}
+
+	err = __mthca_modify_qp(ibqp, attr, attr_mask, cur_state, new_state);
 
 out:
 	mutex_unlock(&qp->mutex);