Commit de910bd9 authored by Or Gerlitz's avatar Or Gerlitz Committed by Roland Dreier
Browse files

RDMA/cma: Simplify locking needed for serialization of callbacks 



The RDMA CM has some logic in place to make sure that callbacks on a
given CM ID are delivered to the consumer in a serialized manner.
Specifically it has code to protect against a device removal racing
with a running callback function.

This patch simplifies this logic by using a mutex per ID instead of a
wait queue and atomic variable.  This means that cma_disable_remove()
now is more properly named to cma_disable_callback(), and
cma_enable_remove() can now be removed because it just would become a
trivial wrapper around mutex_unlock().

Signed-off-by: default avatarOr Gerlitz <ogerlitz@voltaire.com>
Signed-off-by: default avatarRoland Dreier <rolandd@cisco.com>
parent 64c5e613

drivers/infiniband/core/cma.c

+50 −56
Original line number Diff line number Diff line
@@ -130,8 +130,7 @@ struct rdma_id_private { 


	struct completion	comp;

	atomic_t		refcount;

	wait_queue_head_t	wait_remove;

	atomic_t		dev_remove;

	struct mutex		handler_mutex;



	int			backlog;

	int			timeout_ms;
@@ -355,26 +354,15 @@ static void cma_deref_id(struct rdma_id_private *id_priv) 
		complete(&id_priv->comp);

}



static int cma_disable_remove(struct rdma_id_private *id_priv,

static int cma_disable_callback(struct rdma_id_private *id_priv,

			      enum cma_state state)

{

	unsigned long flags;

	int ret;



	spin_lock_irqsave(&id_priv->lock, flags);

	if (id_priv->state == state) {

		atomic_inc(&id_priv->dev_remove);

		ret = 0;

	} else

		ret = -EINVAL;

	spin_unlock_irqrestore(&id_priv->lock, flags);

	return ret;

	mutex_lock(&id_priv->handler_mutex);

	if (id_priv->state != state) {

		mutex_unlock(&id_priv->handler_mutex);

		return -EINVAL;

	}



static void cma_enable_remove(struct rdma_id_private *id_priv)

{

	if (atomic_dec_and_test(&id_priv->dev_remove))

		wake_up(&id_priv->wait_remove);

	return 0;

}



static int cma_has_cm_dev(struct rdma_id_private *id_priv)
@@ -399,8 +387,7 @@ struct rdma_cm_id *rdma_create_id(rdma_cm_event_handler event_handler, 
	mutex_init(&id_priv->qp_mutex);

	init_completion(&id_priv->comp);

	atomic_set(&id_priv->refcount, 1);

	init_waitqueue_head(&id_priv->wait_remove);

	atomic_set(&id_priv->dev_remove, 0);

	mutex_init(&id_priv->handler_mutex);

	INIT_LIST_HEAD(&id_priv->listen_list);

	INIT_LIST_HEAD(&id_priv->mc_list);

	get_random_bytes(&id_priv->seq_num, sizeof id_priv->seq_num);
@@ -927,7 +914,7 @@ static int cma_ib_handler(struct ib_cm_id *cm_id, struct ib_cm_event *ib_event) 
	struct rdma_cm_event event;

	int ret = 0;



	if (cma_disable_remove(id_priv, CMA_CONNECT))

	if (cma_disable_callback(id_priv, CMA_CONNECT))

		return 0;



	memset(&event, 0, sizeof event);
@@ -984,12 +971,12 @@ static int cma_ib_handler(struct ib_cm_id *cm_id, struct ib_cm_event *ib_event) 
		/* Destroy the CM ID by returning a non-zero value. */

		id_priv->cm_id.ib = NULL;

		cma_exch(id_priv, CMA_DESTROYING);

		cma_enable_remove(id_priv);

		mutex_unlock(&id_priv->handler_mutex);

		rdma_destroy_id(&id_priv->id);

		return ret;

	}

out:

	cma_enable_remove(id_priv);

	mutex_unlock(&id_priv->handler_mutex);

	return ret;

}
@@ -1101,7 +1088,7 @@ static int cma_req_handler(struct ib_cm_id *cm_id, struct ib_cm_event *ib_event) 
	int offset, ret;



	listen_id = cm_id->context;

	if (cma_disable_remove(listen_id, CMA_LISTEN))

	if (cma_disable_callback(listen_id, CMA_LISTEN))

		return -ECONNABORTED;



	memset(&event, 0, sizeof event);
@@ -1122,7 +1109,7 @@ static int cma_req_handler(struct ib_cm_id *cm_id, struct ib_cm_event *ib_event) 
		goto out;

	}



	atomic_inc(&conn_id->dev_remove);

	mutex_lock_nested(&conn_id->handler_mutex, SINGLE_DEPTH_NESTING);

	mutex_lock(&lock);

	ret = cma_acquire_dev(conn_id);

	mutex_unlock(&lock);
@@ -1144,7 +1131,7 @@ static int cma_req_handler(struct ib_cm_id *cm_id, struct ib_cm_event *ib_event) 
		    !cma_is_ud_ps(conn_id->id.ps))

			ib_send_cm_mra(cm_id, CMA_CM_MRA_SETTING, NULL, 0);

		mutex_unlock(&lock);

		cma_enable_remove(conn_id);

		mutex_unlock(&conn_id->handler_mutex);

		goto out;

	}
@@ -1153,11 +1140,11 @@ static int cma_req_handler(struct ib_cm_id *cm_id, struct ib_cm_event *ib_event) 


release_conn_id:

	cma_exch(conn_id, CMA_DESTROYING);

	cma_enable_remove(conn_id);

	mutex_unlock(&conn_id->handler_mutex);

	rdma_destroy_id(&conn_id->id);



out:

	cma_enable_remove(listen_id);

	mutex_unlock(&listen_id->handler_mutex);

	return ret;

}
@@ -1223,7 +1210,7 @@ static int cma_iw_handler(struct iw_cm_id *iw_id, struct iw_cm_event *iw_event) 
	struct sockaddr_in *sin;

	int ret = 0;



	if (cma_disable_remove(id_priv, CMA_CONNECT))

	if (cma_disable_callback(id_priv, CMA_CONNECT))

		return 0;



	memset(&event, 0, sizeof event);
@@ -1267,12 +1254,12 @@ static int cma_iw_handler(struct iw_cm_id *iw_id, struct iw_cm_event *iw_event) 
		/* Destroy the CM ID by returning a non-zero value. */

		id_priv->cm_id.iw = NULL;

		cma_exch(id_priv, CMA_DESTROYING);

		cma_enable_remove(id_priv);

		mutex_unlock(&id_priv->handler_mutex);

		rdma_destroy_id(&id_priv->id);

		return ret;

	}



	cma_enable_remove(id_priv);

	mutex_unlock(&id_priv->handler_mutex);

	return ret;

}
@@ -1288,7 +1275,7 @@ static int iw_conn_req_handler(struct iw_cm_id *cm_id, 
	struct ib_device_attr attr;



	listen_id = cm_id->context;

	if (cma_disable_remove(listen_id, CMA_LISTEN))

	if (cma_disable_callback(listen_id, CMA_LISTEN))

		return -ECONNABORTED;



	/* Create a new RDMA id for the new IW CM ID */
@@ -1300,19 +1287,19 @@ static int iw_conn_req_handler(struct iw_cm_id *cm_id, 
		goto out;

	}

	conn_id = container_of(new_cm_id, struct rdma_id_private, id);

	atomic_inc(&conn_id->dev_remove);

	mutex_lock_nested(&conn_id->handler_mutex, SINGLE_DEPTH_NESTING);

	conn_id->state = CMA_CONNECT;



	dev = ip_dev_find(&init_net, iw_event->local_addr.sin_addr.s_addr);

	if (!dev) {

		ret = -EADDRNOTAVAIL;

		cma_enable_remove(conn_id);

		mutex_unlock(&conn_id->handler_mutex);

		rdma_destroy_id(new_cm_id);

		goto out;

	}

	ret = rdma_copy_addr(&conn_id->id.route.addr.dev_addr, dev, NULL);

	if (ret) {

		cma_enable_remove(conn_id);

		mutex_unlock(&conn_id->handler_mutex);

		rdma_destroy_id(new_cm_id);

		goto out;

	}
@@ -1321,7 +1308,7 @@ static int iw_conn_req_handler(struct iw_cm_id *cm_id, 
	ret = cma_acquire_dev(conn_id);

	mutex_unlock(&lock);

	if (ret) {

		cma_enable_remove(conn_id);

		mutex_unlock(&conn_id->handler_mutex);

		rdma_destroy_id(new_cm_id);

		goto out;

	}
@@ -1337,7 +1324,7 @@ static int iw_conn_req_handler(struct iw_cm_id *cm_id, 


	ret = ib_query_device(conn_id->id.device, &attr);

	if (ret) {

		cma_enable_remove(conn_id);

		mutex_unlock(&conn_id->handler_mutex);

		rdma_destroy_id(new_cm_id);

		goto out;

	}
@@ -1353,14 +1340,17 @@ static int iw_conn_req_handler(struct iw_cm_id *cm_id, 
		/* User wants to destroy the CM ID */

		conn_id->cm_id.iw = NULL;

		cma_exch(conn_id, CMA_DESTROYING);

		cma_enable_remove(conn_id);

		mutex_unlock(&conn_id->handler_mutex);

		rdma_destroy_id(&conn_id->id);

		goto out;

	}



	mutex_unlock(&conn_id->handler_mutex);



out:

	if (dev)

		dev_put(dev);

	cma_enable_remove(listen_id);

	mutex_unlock(&listen_id->handler_mutex);

	return ret;

}
@@ -1592,7 +1582,7 @@ static void cma_work_handler(struct work_struct *_work) 
	struct rdma_id_private *id_priv = work->id;

	int destroy = 0;



	atomic_inc(&id_priv->dev_remove);

	mutex_lock(&id_priv->handler_mutex);

	if (!cma_comp_exch(id_priv, work->old_state, work->new_state))

		goto out;
@@ -1601,7 +1591,7 @@ static void cma_work_handler(struct work_struct *_work) 
		destroy = 1;

	}

out:

	cma_enable_remove(id_priv);

	mutex_unlock(&id_priv->handler_mutex);

	cma_deref_id(id_priv);

	if (destroy)

		rdma_destroy_id(&id_priv->id);
@@ -1764,7 +1754,7 @@ static void addr_handler(int status, struct sockaddr *src_addr, 
	struct rdma_cm_event event;



	memset(&event, 0, sizeof event);

	atomic_inc(&id_priv->dev_remove);

	mutex_lock(&id_priv->handler_mutex);



	/*

	 * Grab mutex to block rdma_destroy_id() from removing the device while
@@ -1793,13 +1783,13 @@ static void addr_handler(int status, struct sockaddr *src_addr, 


	if (id_priv->id.event_handler(&id_priv->id, &event)) {

		cma_exch(id_priv, CMA_DESTROYING);

		cma_enable_remove(id_priv);

		mutex_unlock(&id_priv->handler_mutex);

		cma_deref_id(id_priv);

		rdma_destroy_id(&id_priv->id);

		return;

	}

out:

	cma_enable_remove(id_priv);

	mutex_unlock(&id_priv->handler_mutex);

	cma_deref_id(id_priv);

}
@@ -2126,7 +2116,7 @@ static int cma_sidr_rep_handler(struct ib_cm_id *cm_id, 
	struct ib_cm_sidr_rep_event_param *rep = &ib_event->param.sidr_rep_rcvd;

	int ret = 0;



	if (cma_disable_remove(id_priv, CMA_CONNECT))

	if (cma_disable_callback(id_priv, CMA_CONNECT))

		return 0;



	memset(&event, 0, sizeof event);
@@ -2167,12 +2157,12 @@ static int cma_sidr_rep_handler(struct ib_cm_id *cm_id, 
		/* Destroy the CM ID by returning a non-zero value. */

		id_priv->cm_id.ib = NULL;

		cma_exch(id_priv, CMA_DESTROYING);

		cma_enable_remove(id_priv);

		mutex_unlock(&id_priv->handler_mutex);

		rdma_destroy_id(&id_priv->id);

		return ret;

	}

out:

	cma_enable_remove(id_priv);

	mutex_unlock(&id_priv->handler_mutex);

	return ret;

}
@@ -2570,8 +2560,8 @@ static int cma_ib_mc_handler(int status, struct ib_sa_multicast *multicast) 
	int ret;



	id_priv = mc->id_priv;

	if (cma_disable_remove(id_priv, CMA_ADDR_BOUND) &&

	    cma_disable_remove(id_priv, CMA_ADDR_RESOLVED))

	if (cma_disable_callback(id_priv, CMA_ADDR_BOUND) &&

	    cma_disable_callback(id_priv, CMA_ADDR_RESOLVED))

		return 0;



	mutex_lock(&id_priv->qp_mutex);
@@ -2596,12 +2586,12 @@ static int cma_ib_mc_handler(int status, struct ib_sa_multicast *multicast) 
	ret = id_priv->id.event_handler(&id_priv->id, &event);

	if (ret) {

		cma_exch(id_priv, CMA_DESTROYING);

		cma_enable_remove(id_priv);

		mutex_unlock(&id_priv->handler_mutex);

		rdma_destroy_id(&id_priv->id);

		return 0;

	}



	cma_enable_remove(id_priv);

	mutex_unlock(&id_priv->handler_mutex);

	return 0;

}
@@ -2760,6 +2750,7 @@ static int cma_remove_id_dev(struct rdma_id_private *id_priv) 
{

	struct rdma_cm_event event;

	enum cma_state state;

	int ret = 0;



	/* Record that we want to remove the device */

	state = cma_exch(id_priv, CMA_DEVICE_REMOVAL);
@@ -2767,15 +2758,18 @@ static int cma_remove_id_dev(struct rdma_id_private *id_priv) 
		return 0;



	cma_cancel_operation(id_priv, state);

	wait_event(id_priv->wait_remove, !atomic_read(&id_priv->dev_remove));

	mutex_lock(&id_priv->handler_mutex);



	/* Check for destruction from another callback. */

	if (!cma_comp(id_priv, CMA_DEVICE_REMOVAL))

		return 0;

		goto out;



	memset(&event, 0, sizeof event);

	event.event = RDMA_CM_EVENT_DEVICE_REMOVAL;

	return id_priv->id.event_handler(&id_priv->id, &event);

	ret = id_priv->id.event_handler(&id_priv->id, &event);

out:

	mutex_unlock(&id_priv->handler_mutex);

	return ret;

}



static void cma_process_remove(struct cma_device *cma_dev)

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