iw_cxgb4: Fix qpid leak

Add await in destroy_qp() so that all references to qp are dereferenced
and qp is freed in destroy_qp() itself.  This ensures freeing of all QPs
before invocation of dealloc_ucontext(), which prevents loss of in use
qpids stored in the ucontext.

Signed-off-by: Nirranjan Kirubaharan <nirranjan@chelsio.com>
Reviewed-by: Potnuri Bharat Teja <bharat@chelsio.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/cxgb4/iw_cxgb4.h

@@ -490,13 +490,13 @@ struct c4iw_qp {
 	struct t4_wq wq;
 	spinlock_t lock;
 	struct mutex mutex;
-	struct kref kref;
 	wait_queue_head_t wait;
 	int sq_sig_all;
 	struct c4iw_srq *srq;
-	struct work_struct free_work;
 	struct c4iw_ucontext *ucontext;
 	struct c4iw_wr_wait *wr_waitp;
+	struct completion qp_rel_comp;
+	refcount_t qp_refcnt;
 };
 
 static inline struct c4iw_qp *to_c4iw_qp(struct ib_qp *ibqp)

drivers/infiniband/hw/cxgb4/qp.c

@@ -890,43 +890,17 @@ static int build_inv_stag(union t4_wr *wqe, const struct ib_send_wr *wr,
 	return 0;
 }
 
-static void free_qp_work(struct work_struct *work)
-{
-	struct c4iw_ucontext *ucontext;
-	struct c4iw_qp *qhp;
-	struct c4iw_dev *rhp;
-
-	qhp = container_of(work, struct c4iw_qp, free_work);
-	ucontext = qhp->ucontext;
-	rhp = qhp->rhp;
-
-	pr_debug("qhp %p ucontext %p\n", qhp, ucontext);
-	destroy_qp(&rhp->rdev, &qhp->wq,
-		   ucontext ? &ucontext->uctx : &rhp->rdev.uctx, !qhp->srq);
-
-	c4iw_put_wr_wait(qhp->wr_waitp);
-	kfree(qhp);
-}
-
-static void queue_qp_free(struct kref *kref)
-{
-	struct c4iw_qp *qhp;
-
-	qhp = container_of(kref, struct c4iw_qp, kref);
-	pr_debug("qhp %p\n", qhp);
-	queue_work(qhp->rhp->rdev.free_workq, &qhp->free_work);
-}
-
 void c4iw_qp_add_ref(struct ib_qp *qp)
 {
 	pr_debug("ib_qp %p\n", qp);
-	kref_get(&to_c4iw_qp(qp)->kref);
+	refcount_inc(&to_c4iw_qp(qp)->qp_refcnt);
 }
 
 void c4iw_qp_rem_ref(struct ib_qp *qp)
 {
 	pr_debug("ib_qp %p\n", qp);
-	kref_put(&to_c4iw_qp(qp)->kref, queue_qp_free);
+	if (refcount_dec_and_test(&to_c4iw_qp(qp)->qp_refcnt))
+		complete(&to_c4iw_qp(qp)->qp_rel_comp);
 }
 
 static void add_to_fc_list(struct list_head *head, struct list_head *entry)
@@ -2098,10 +2072,12 @@ int c4iw_destroy_qp(struct ib_qp *ib_qp, struct ib_udata *udata)
 {
 	struct c4iw_dev *rhp;
 	struct c4iw_qp *qhp;
+	struct c4iw_ucontext *ucontext;
 	struct c4iw_qp_attributes attrs;
 
 	qhp = to_c4iw_qp(ib_qp);
 	rhp = qhp->rhp;
+	ucontext = qhp->ucontext;
 
 	attrs.next_state = C4IW_QP_STATE_ERROR;
 	if (qhp->attr.state == C4IW_QP_STATE_TERMINATE)
@@ -2119,7 +2095,17 @@ int c4iw_destroy_qp(struct ib_qp *ib_qp, struct ib_udata *udata)
 
 	c4iw_qp_rem_ref(ib_qp);
 
+	wait_for_completion(&qhp->qp_rel_comp);
+
 	pr_debug("ib_qp %p qpid 0x%0x\n", ib_qp, qhp->wq.sq.qid);
+	pr_debug("qhp %p ucontext %p\n", qhp, ucontext);
+
+	destroy_qp(&rhp->rdev, &qhp->wq,
+		   ucontext ? &ucontext->uctx : &rhp->rdev.uctx, !qhp->srq);
+
+	c4iw_put_wr_wait(qhp->wr_waitp);
+
+	kfree(qhp);
 	return 0;
 }
 
@@ -2229,8 +2215,8 @@ struct ib_qp *c4iw_create_qp(struct ib_pd *pd, struct ib_qp_init_attr *attrs,
 	spin_lock_init(&qhp->lock);
 	mutex_init(&qhp->mutex);
 	init_waitqueue_head(&qhp->wait);
-	kref_init(&qhp->kref);
-	INIT_WORK(&qhp->free_work, free_qp_work);
+	init_completion(&qhp->qp_rel_comp);
+	refcount_set(&qhp->qp_refcnt, 1);
 
 	ret = xa_insert_irq(&rhp->qps, qhp->wq.sq.qid, qhp, GFP_KERNEL);
 	if (ret)