[PATCH] RDMA/siw: publish QP after initialization

[Ruoyu Wang <ruoyuw560@gmail.com>]

siw_create_qp() allocates a QP number before the queues, CQ pointers,
state, completion, and device list entry are ready. A QPN lookup can
therefore reach a QP that is still being constructed if the object is
published at allocation time.

Reserve the QPN with an empty XArray entry first. Publish the QP object
only after the kernel-visible QP state is initialized and just before
siw_create_qp() returns it to the caller.

Fixes: f29dd55b0236 ("rdma/siw: queue pair methods")
Signed-off-by: Ruoyu Wang <ruoyuw560@gmail.com>
---
 drivers/infiniband/sw/siw/siw.h       |  1 +
 drivers/infiniband/sw/siw/siw_qp.c    | 26 ++++++++++++++++++--------
 drivers/infiniband/sw/siw/siw_verbs.c | 12 +++++++++++-
 3 files changed, 30 insertions(+), 9 deletions(-)

diff --git a/drivers/infiniband/sw/siw/siw.h b/drivers/infiniband/sw/siw/siw.h
index f5fd71717b80..ade7c96135c2 100644
--- a/drivers/infiniband/sw/siw/siw.h
+++ b/drivers/infiniband/sw/siw/siw.h
@@ -511,6 +511,7 @@ void siw_send_terminate(struct siw_qp *qp);
 void siw_qp_get_ref(struct ib_qp *qp);
 void siw_qp_put_ref(struct ib_qp *qp);
 int siw_qp_add(struct siw_device *sdev, struct siw_qp *qp);
+int siw_qp_publish(struct siw_qp *qp);
 void siw_free_qp(struct kref *ref);
 
 void siw_init_terminate(struct siw_qp *qp, enum term_elayer layer,
diff --git a/drivers/infiniband/sw/siw/siw_qp.c b/drivers/infiniband/sw/siw/siw_qp.c
index bb780e3904a2..1a9135d9a2a7 100644
--- a/drivers/infiniband/sw/siw/siw_qp.c
+++ b/drivers/infiniband/sw/siw/siw_qp.c
@@ -1281,15 +1281,25 @@ void siw_rq_flush(struct siw_qp *qp)
 
 int siw_qp_add(struct siw_device *sdev, struct siw_qp *qp)
 {
-	int rv = xa_alloc(&sdev->qp_xa, &qp->base_qp.qp_num, qp, xa_limit_32b,
-			  GFP_KERNEL);
+	qp->sdev = sdev;
 
-	if (!rv) {
-		kref_init(&qp->ref);
-		qp->sdev = sdev;
-		siw_dbg_qp(qp, "new QP\n");
-	}
-	return rv;
+	return xa_alloc(&sdev->qp_xa, &qp->base_qp.qp_num, NULL,
+			xa_limit_32b, GFP_KERNEL);
+}
+
+int siw_qp_publish(struct siw_qp *qp)
+{
+	void *old;
+
+	kref_init(&qp->ref);
+
+	old = xa_store(&qp->sdev->qp_xa, qp_id(qp), qp, GFP_KERNEL);
+	if (xa_is_err(old))
+		return xa_err(old);
+
+	siw_dbg_qp(qp, "new QP\n");
+
+	return 0;
 }
 
 void siw_free_qp(struct kref *ref)
diff --git a/drivers/infiniband/sw/siw/siw_verbs.c b/drivers/infiniband/sw/siw/siw_verbs.c
index 1e1d262a4ae2..71bc0cc59e3d 100644
--- a/drivers/infiniband/sw/siw/siw_verbs.c
+++ b/drivers/infiniband/sw/siw/siw_verbs.c
@@ -482,14 +482,24 @@ int siw_create_qp(struct ib_qp *ibqp, struct ib_qp_init_attr *attrs,
 		goto err_out_xa;
 	}
 	INIT_LIST_HEAD(&qp->devq);
+	init_completion(&qp->qp_free);
+
 	spin_lock_irqsave(&sdev->lock, flags);
 	list_add_tail(&qp->devq, &sdev->qp_list);
 	spin_unlock_irqrestore(&sdev->lock, flags);
 
-	init_completion(&qp->qp_free);
+	rv = siw_qp_publish(qp);
+	if (rv)
+		goto err_out_list;
 
 	return 0;
 
+err_out_list:
+	spin_lock_irqsave(&sdev->lock, flags);
+	list_del(&qp->devq);
+	spin_unlock_irqrestore(&sdev->lock, flags);
+
+	siw_put_tx_cpu(qp->tx_cpu);
 err_out_xa:
 	xa_erase(&sdev->qp_xa, qp_id(qp));
 	if (uctx) {