iw_cxgb4: don't block in destroy_qp awaiting the last deref
Blocking in c4iw_destroy_qp() causes a deadlock when apps destroy a qp
or disconnect a cm_id from their cm event handler function. There is
no need to block here anyway, so just replace the refcnt atomic with a
kref object and free the memory on the last put.
Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Doug Ledford <dledford@redhat.com>
diff --git a/drivers/infiniband/hw/cxgb4/qp.c b/drivers/infiniband/hw/cxgb4/qp.c
index 28a76a5..edb1172 100644
--- a/drivers/infiniband/hw/cxgb4/qp.c
+++ b/drivers/infiniband/hw/cxgb4/qp.c
@@ -683,17 +683,25 @@
return 0;
}
+void _free_qp(struct kref *kref)
+{
+ struct c4iw_qp *qhp;
+
+ qhp = container_of(kref, struct c4iw_qp, kref);
+ PDBG("%s qhp %p\n", __func__, qhp);
+ kfree(qhp);
+}
+
void c4iw_qp_add_ref(struct ib_qp *qp)
{
PDBG("%s ib_qp %p\n", __func__, qp);
- atomic_inc(&(to_c4iw_qp(qp)->refcnt));
+ kref_get(&to_c4iw_qp(qp)->kref);
}
void c4iw_qp_rem_ref(struct ib_qp *qp)
{
PDBG("%s ib_qp %p\n", __func__, qp);
- if (atomic_dec_and_test(&(to_c4iw_qp(qp)->refcnt)))
- wake_up(&(to_c4iw_qp(qp)->wait));
+ kref_put(&to_c4iw_qp(qp)->kref, _free_qp);
}
static void add_to_fc_list(struct list_head *head, struct list_head *entry)
@@ -1594,8 +1602,6 @@
wait_event(qhp->wait, !qhp->ep);
remove_handle(rhp, &rhp->qpidr, qhp->wq.sq.qid);
- atomic_dec(&qhp->refcnt);
- wait_event(qhp->wait, !atomic_read(&qhp->refcnt));
spin_lock_irq(&rhp->lock);
if (!list_empty(&qhp->db_fc_entry))
@@ -1608,8 +1614,9 @@
destroy_qp(&rhp->rdev, &qhp->wq,
ucontext ? &ucontext->uctx : &rhp->rdev.uctx);
+ c4iw_qp_rem_ref(ib_qp);
+
PDBG("%s ib_qp %p qpid 0x%0x\n", __func__, ib_qp, qhp->wq.sq.qid);
- kfree(qhp);
return 0;
}
@@ -1706,7 +1713,7 @@
init_completion(&qhp->rq_drained);
mutex_init(&qhp->mutex);
init_waitqueue_head(&qhp->wait);
- atomic_set(&qhp->refcnt, 1);
+ kref_init(&qhp->kref);
ret = insert_handle(rhp, &rhp->qpidr, qhp, qhp->wq.sq.qid);
if (ret)