1 files changed, 27 insertions, 21 deletions

diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
index d86fbabe48d6..ea8661a00651 100644
--- a/drivers/infiniband/core/device.c
+++ b/drivers/infiniband/core/device.c
@@ -94,7 +94,7 @@ static DEFINE_XARRAY_FLAGS(devices, XA_FLAGS_ALLOC);
 static DECLARE_RWSEM(devices_rwsem);
 #define DEVICE_REGISTERED XA_MARK_1
 
-static LIST_HEAD(client_list);
+static u32 highest_client_id;
 #define CLIENT_REGISTERED XA_MARK_1
 static DEFINE_XARRAY_FLAGS(clients, XA_FLAGS_ALLOC);
 static DECLARE_RWSEM(clients_rwsem);
@@ -1237,7 +1237,7 @@ static int setup_device(struct ib_device *device)
 
 static void disable_device(struct ib_device *device)
 {
-	struct ib_client *client;
+	u32 cid;
 
 	WARN_ON(!refcount_read(&device->refcount));
 
@@ -1245,10 +1245,19 @@ static void disable_device(struct ib_device *device)
 	xa_clear_mark(&devices, device->index, DEVICE_REGISTERED);
 	up_write(&devices_rwsem);
 
+	/*
+	 * Remove clients in LIFO order, see assign_client_id. This could be
+	 * more efficient if xarray learns to reverse iterate. Since no new
+	 * clients can be added to this ib_device past this point we only need
+	 * the maximum possible client_id value here.
+	 */
 	down_read(&clients_rwsem);
-	list_for_each_entry_reverse(client, &client_list, list)
-		remove_client_context(device, client->client_id);
+	cid = highest_client_id;
 	up_read(&clients_rwsem);
+	while (cid) {
+		cid--;
+		remove_client_context(device, cid);
+	}
 
 	/* Pairs with refcount_set in enable_device */
 	ib_device_put(device);
@@ -1675,30 +1684,31 @@ static int assign_client_id(struct ib_client *client)
 	/*
 	 * The add/remove callbacks must be called in FIFO/LIFO order. To
 	 * achieve this we assign client_ids so they are sorted in
-	 * registration order, and retain a linked list we can reverse iterate
-	 * to get the LIFO order. The extra linked list can go away if xarray
-	 * learns to reverse iterate.
+	 * registration order.
 	 */
-	if (list_empty(&client_list)) {
-		client->client_id = 0;
-	} else {
-		struct ib_client *last;
-
-		last = list_last_entry(&client_list, struct ib_client, list);
-		client->client_id = last->client_id + 1;
-	}
+	client->client_id = highest_client_id;
 	ret = xa_insert(&clients, client->client_id, client, GFP_KERNEL);
 	if (ret)
 		goto out;
 
+	highest_client_id++;
 	xa_set_mark(&clients, client->client_id, CLIENT_REGISTERED);
-	list_add_tail(&client->list, &client_list);
 
 out:
 	up_write(&clients_rwsem);
 	return ret;
 }
 
+static void remove_client_id(struct ib_client *client)
+{
+	down_write(&clients_rwsem);
+	xa_erase(&clients, client->client_id);
+	for (; highest_client_id; highest_client_id--)
+		if (xa_load(&clients, highest_client_id - 1))
+			break;
+	up_write(&clients_rwsem);
+}
+
 /**
  * ib_register_client - Register an IB client
  * @client:Client to register
@@ -1778,11 +1788,7 @@ void ib_unregister_client(struct ib_client *client)
 	 * removal is ongoing. Wait until all removals are completed.
 	 */
 	wait_for_completion(&client->uses_zero);
-
-	down_write(&clients_rwsem);
-	list_del(&client->list);
-	xa_erase(&clients, client->client_id);
-	up_write(&clients_rwsem);
+	remove_client_id(client);
 }
 EXPORT_SYMBOL(ib_unregister_client);