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@@ -53,6 +53,12 @@ MODULE_PARM_DESC(fmr_message_size, " Max size of a RDMA transfer");
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module_param(rds_ib_retry_count, int, 0444);
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MODULE_PARM_DESC(rds_ib_retry_count, " Number of hw retries before reporting an error");
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+/*
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+ * we have a clumsy combination of RCU and a rwsem protecting this list
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+ * because it is used both in the get_mr fast path and while blocking in
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+ * the FMR flushing path.
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+ */
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+DECLARE_RWSEM(rds_ib_devices_lock);
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struct list_head rds_ib_devices;
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/* NOTE: if also grabbing ibdev lock, grab this first */
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@@ -171,7 +177,10 @@ void rds_ib_add_one(struct ib_device *device)
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INIT_LIST_HEAD(&rds_ibdev->ipaddr_list);
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INIT_LIST_HEAD(&rds_ibdev->conn_list);
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- list_add_tail(&rds_ibdev->list, &rds_ib_devices);
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+
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+ down_write(&rds_ib_devices_lock);
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+ list_add_tail_rcu(&rds_ibdev->list, &rds_ib_devices);
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+ up_write(&rds_ib_devices_lock);
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atomic_inc(&rds_ibdev->refcount);
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ib_set_client_data(device, &rds_ib_client, rds_ibdev);
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@@ -230,16 +239,20 @@ void rds_ib_remove_one(struct ib_device *device)
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rds_ib_dev_shutdown(rds_ibdev);
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+ /* stop connection attempts from getting a reference to this device. */
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+ ib_set_client_data(device, &rds_ib_client, NULL);
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+
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+ down_write(&rds_ib_devices_lock);
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+ list_del_rcu(&rds_ibdev->list);
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+ up_write(&rds_ib_devices_lock);
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+
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/*
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- * prevent future connection attempts from getting a reference to this
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- * device and wait for currently racing connection attempts to finish
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- * getting their reference
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+ * This synchronize rcu is waiting for readers of both the ib
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+ * client data and the devices list to finish before we drop
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+ * both of those references.
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*/
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- ib_set_client_data(device, &rds_ib_client, NULL);
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synchronize_rcu();
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rds_ib_dev_put(rds_ibdev);
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-
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- list_del(&rds_ibdev->list);
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rds_ib_dev_put(rds_ibdev);
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}
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