diff options
Diffstat (limited to 'net/rds/ib.c')
| -rw-r--r-- | net/rds/ib.c | 27 |
1 files changed, 20 insertions, 7 deletions
diff --git a/net/rds/ib.c b/net/rds/ib.c index 3eb5617649c..b12a3951167 100644 --- a/net/rds/ib.c +++ b/net/rds/ib.c @@ -53,6 +53,12 @@ MODULE_PARM_DESC(fmr_message_size, " Max size of a RDMA transfer"); module_param(rds_ib_retry_count, int, 0444); MODULE_PARM_DESC(rds_ib_retry_count, " Number of hw retries before reporting an error"); +/* + * we have a clumsy combination of RCU and a rwsem protecting this list + * because it is used both in the get_mr fast path and while blocking in + * the FMR flushing path. + */ +DECLARE_RWSEM(rds_ib_devices_lock); struct list_head rds_ib_devices; /* NOTE: if also grabbing ibdev lock, grab this first */ @@ -171,7 +177,10 @@ void rds_ib_add_one(struct ib_device *device) INIT_LIST_HEAD(&rds_ibdev->ipaddr_list); INIT_LIST_HEAD(&rds_ibdev->conn_list); - list_add_tail(&rds_ibdev->list, &rds_ib_devices); + + down_write(&rds_ib_devices_lock); + list_add_tail_rcu(&rds_ibdev->list, &rds_ib_devices); + up_write(&rds_ib_devices_lock); atomic_inc(&rds_ibdev->refcount); ib_set_client_data(device, &rds_ib_client, rds_ibdev); @@ -230,16 +239,20 @@ void rds_ib_remove_one(struct ib_device *device) rds_ib_dev_shutdown(rds_ibdev); + /* stop connection attempts from getting a reference to this device. */ + ib_set_client_data(device, &rds_ib_client, NULL); + + down_write(&rds_ib_devices_lock); + list_del_rcu(&rds_ibdev->list); + up_write(&rds_ib_devices_lock); + /* - * prevent future connection attempts from getting a reference to this - * device and wait for currently racing connection attempts to finish - * getting their reference + * This synchronize rcu is waiting for readers of both the ib + * client data and the devices list to finish before we drop + * both of those references. */ - ib_set_client_data(device, &rds_ib_client, NULL); synchronize_rcu(); rds_ib_dev_put(rds_ibdev); - - list_del(&rds_ibdev->list); rds_ib_dev_put(rds_ibdev); } |