Merge v7.1.5linux-rolling-stable

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 49 insertions, 0 deletions

diff --git a/drivers/infiniband/core/restrack.c b/drivers/infiniband/core/restrack.c
index ac3688952cab..cfee2071586c 100644
--- a/drivers/infiniband/core/restrack.c
+++ b/drivers/infiniband/core/restrack.c
@@ -71,6 +71,8 @@ int rdma_restrack_count(struct ib_device *dev, enum rdma_restrack_type type,
 
 	xa_lock(&rt->xa);
 	xas_for_each(&xas, e, U32_MAX) {
+		if (xa_is_zero(e))
+			continue;
 		if (xa_get_mark(&rt->xa, e->id, RESTRACK_DD) && !show_details)
 			continue;
 		cnt++;
@@ -277,6 +279,53 @@ int rdma_restrack_put(struct rdma_restrack_entry *res)
 EXPORT_SYMBOL(rdma_restrack_put);
 
 /**
+ * rdma_restrack_sync() - Fence concurrent netlink dumps on an entry
+ * @res:  resource entry
+ *
+ * After this returns any concurrent netlink dump threads will see the current
+ * value of the object. This is useful if the object has to be changed and there
+ * is not locking to protect the nl side. Eg for mr->pd. This effectively
+ * destroys the object from a kref/xarray perspective and then immediately
+ * restores it. The kref is acting like a lock to barrier concurrent nl threads.
+ * Callers must ensure rdma_restrack_del() is not concurrently called.
+ */
+void rdma_restrack_sync(struct rdma_restrack_entry *res)
+{
+	struct rdma_restrack_entry *old;
+	struct rdma_restrack_root *rt;
+	struct task_struct *task;
+	struct ib_device *dev;
+
+	if (!res->valid || res->no_track)
+		return;
+
+	dev = res_to_dev(res);
+	if (WARN_ON(!dev))
+		return;
+
+	rt = &dev->res[res->type];
+	if (WARN_ON(xa_get_mark(&rt->xa, res->id, RESTRACK_DD)))
+		return;
+
+	old = xa_cmpxchg(&rt->xa, res->id, res, XA_ZERO_ENTRY, GFP_KERNEL);
+	if (WARN_ON(old != res))
+		return;
+
+	task = res->task;
+	if (task)
+		get_task_struct(task);
+	rdma_restrack_put(res);
+	wait_for_completion(&res->comp);
+	reinit_completion(&res->comp);
+	if (task)
+		res->task = task;
+	kref_init(&res->kref);
+
+	xa_cmpxchg(&rt->xa, res->id, XA_ZERO_ENTRY, res, GFP_KERNEL);
+}
+EXPORT_SYMBOL(rdma_restrack_sync);
+
+/**
  * rdma_restrack_del() - delete object from the resource tracking database
  * @res:  resource entry
  */