1 files changed, 95 insertions, 34 deletions

diff --git a/net/rds/ib.c b/net/rds/ib.c
index 7d289d7985fe..1732f8effb59 100644
--- a/net/rds/ib.c
+++ b/net/rds/ib.c
@@ -59,6 +59,38 @@ struct list_head rds_ib_devices;
 DEFINE_SPINLOCK(ib_nodev_conns_lock);
 LIST_HEAD(ib_nodev_conns);
 
+/*
+ * rds_ib_destroy_mr_pool() blocks on a few things and mrs drop references
+ * from interrupt context so we push freing off into a work struct in krdsd.
+ */
+static void rds_ib_dev_free(struct work_struct *work)
+{
+        struct rds_ib_ipaddr *i_ipaddr, *i_next;
+        struct rds_ib_device *rds_ibdev = container_of(work,
+                                        struct rds_ib_device, free_work);
+
+        if (rds_ibdev->mr_pool)
+                rds_ib_destroy_mr_pool(rds_ibdev->mr_pool);
+        if (rds_ibdev->mr)
+                ib_dereg_mr(rds_ibdev->mr);
+        if (rds_ibdev->pd)
+                ib_dealloc_pd(rds_ibdev->pd);
+
+        list_for_each_entry_safe(i_ipaddr, i_next, &rds_ibdev->ipaddr_list, list) {
+                list_del(&i_ipaddr->list);
+                kfree(i_ipaddr);
+        }
+
+        kfree(rds_ibdev);
+}
+
+void rds_ib_dev_put(struct rds_ib_device *rds_ibdev)
+{
+        BUG_ON(atomic_read(&rds_ibdev->refcount) <= 0);
+        if (atomic_dec_and_test(&rds_ibdev->refcount))
+                queue_work(rds_wq, &rds_ibdev->free_work);
+}
+
 void rds_ib_add_one(struct ib_device *device)
 {
         struct rds_ib_device *rds_ibdev;
@@ -77,11 +109,14 @@ void rds_ib_add_one(struct ib_device *device)
                 goto free_attr;
         }
 
-        rds_ibdev = kmalloc_node(sizeof *rds_ibdev, GFP_KERNEL, ibdev_to_node(device));
+        rds_ibdev = kzalloc_node(sizeof(struct rds_ib_device), GFP_KERNEL,
+                                 ibdev_to_node(device));
         if (!rds_ibdev)
                 goto free_attr;
 
         spin_lock_init(&rds_ibdev->spinlock);
+        atomic_set(&rds_ibdev->refcount, 1);
+        INIT_WORK(&rds_ibdev->free_work, rds_ib_dev_free);
 
         rds_ibdev->max_wrs = dev_attr->max_qp_wr;
         rds_ibdev->max_sge = min(dev_attr->max_sge, RDS_IB_MAX_SGE);
@@ -96,67 +131,93 @@ void rds_ib_add_one(struct ib_device *device)
 
         rds_ibdev->dev = device;
         rds_ibdev->pd = ib_alloc_pd(device);
-        if (IS_ERR(rds_ibdev->pd))
-                goto free_dev;
+        if (IS_ERR(rds_ibdev->pd)) {
+                rds_ibdev->pd = NULL;
+                goto put_dev;
+        }
 
-        rds_ibdev->mr = ib_get_dma_mr(rds_ibdev->pd,
-                                      IB_ACCESS_LOCAL_WRITE);
-        if (IS_ERR(rds_ibdev->mr))
-                goto err_pd;
+        rds_ibdev->mr = ib_get_dma_mr(rds_ibdev->pd, IB_ACCESS_LOCAL_WRITE);
+        if (IS_ERR(rds_ibdev->mr)) {
+                rds_ibdev->mr = NULL;
+                goto put_dev;
+        }
 
         rds_ibdev->mr_pool = rds_ib_create_mr_pool(rds_ibdev);
         if (IS_ERR(rds_ibdev->mr_pool)) {
                 rds_ibdev->mr_pool = NULL;
-                goto err_mr;
+                goto put_dev;
         }
 
         INIT_LIST_HEAD(&rds_ibdev->ipaddr_list);
         INIT_LIST_HEAD(&rds_ibdev->conn_list);
         list_add_tail(&rds_ibdev->list, &rds_ib_devices);
+        atomic_inc(&rds_ibdev->refcount);
 
         ib_set_client_data(device, &rds_ib_client, rds_ibdev);
+        atomic_inc(&rds_ibdev->refcount);
 
-        goto free_attr;
-
-err_mr:
-        ib_dereg_mr(rds_ibdev->mr);
-err_pd:
-        ib_dealloc_pd(rds_ibdev->pd);
-free_dev:
-        kfree(rds_ibdev);
+put_dev:
+        rds_ib_dev_put(rds_ibdev);
 free_attr:
         kfree(dev_attr);
 }
 
+/*
+ * New connections use this to find the device to associate with the
+ * connection.  It's not in the fast path so we're not concerned about the
+ * performance of the IB call.  (As of this writing, it uses an interrupt
+ * blocking spinlock to serialize walking a per-device list of all registered
+ * clients.)
+ *
+ * RCU is used to handle incoming connections racing with device teardown.
+ * Rather than use a lock to serialize removal from the client_data and
+ * getting a new reference, we use an RCU grace period.  The destruction
+ * path removes the device from client_data and then waits for all RCU
+ * readers to finish.
+ *
+ * A new connection can get NULL from this if its arriving on a
+ * device that is in the process of being removed.
+ */
+struct rds_ib_device *rds_ib_get_client_data(struct ib_device *device)
+{
+        struct rds_ib_device *rds_ibdev;
+
+        rcu_read_lock();
+        rds_ibdev = ib_get_client_data(device, &rds_ib_client);
+        if (rds_ibdev)
+                atomic_inc(&rds_ibdev->refcount);
+        rcu_read_unlock();
+        return rds_ibdev;
+}
+
+/*
+ * The IB stack is letting us know that a device is going away.  This can
+ * happen if the underlying HCA driver is removed or if PCI hotplug is removing
+ * the pci function, for example.
+ *
+ * This can be called at any time and can be racing with any other RDS path.
+ */
 void rds_ib_remove_one(struct ib_device *device)
 {
         struct rds_ib_device *rds_ibdev;
-        struct rds_ib_ipaddr *i_ipaddr, *i_next;
 
         rds_ibdev = ib_get_client_data(device, &rds_ib_client);
         if (!rds_ibdev)
                 return;
 
-        synchronize_rcu();
-        list_for_each_entry_safe(i_ipaddr, i_next, &rds_ibdev->ipaddr_list, list) {
-                list_del(&i_ipaddr->list);
-                kfree(i_ipaddr);
-        }
-
         rds_ib_destroy_conns(rds_ibdev);
 
-        if (rds_ibdev->mr_pool)
-                rds_ib_destroy_mr_pool(rds_ibdev->mr_pool);
-
-        ib_dereg_mr(rds_ibdev->mr);
-
-        while (ib_dealloc_pd(rds_ibdev->pd)) {
-                rdsdebug("Failed to dealloc pd %p\n", rds_ibdev->pd);
-                msleep(1);
-        }
+        /*
+         * prevent future connection attempts from getting a reference to this
+         * device and wait for currently racing connection attempts to finish
+         * getting their reference
+         */
+        ib_set_client_data(device, &rds_ib_client, NULL);
+        synchronize_rcu();
+        rds_ib_dev_put(rds_ibdev);
 
         list_del(&rds_ibdev->list);
-        kfree(rds_ibdev);
+        rds_ib_dev_put(rds_ibdev);
 }
 
 struct ib_client rds_ib_client = {
@@ -190,7 +251,7 @@ static int rds_ib_conn_info_visitor(struct rds_connection *conn,
                 rdma_addr_get_sgid(dev_addr, (union ib_gid *) &iinfo->src_gid);
                 rdma_addr_get_dgid(dev_addr, (union ib_gid *) &iinfo->dst_gid);
 
-                rds_ibdev = ib_get_client_data(ic->i_cm_id->device, &rds_ib_client);
+                rds_ibdev = ic->rds_ibdev;
                 iinfo->max_send_wr = ic->i_send_ring.w_nr;
                 iinfo->max_recv_wr = ic->i_recv_ring.w_nr;
                 iinfo->max_send_sge = rds_ibdev->max_sge;