Commit a396d43a authored by Sean Hefty's avatar Sean Hefty Committed by Roland Dreier
Browse files

RDMA/cma: Replace global lock in rdma_destroy_id() with id-specific one 



rdma_destroy_id currently uses the global rdma cm 'lock' to test if an
rdma_cm_id has been bound to a device.  This prevents an active
address resolution callback handler from assigning a device to the
rdma_cm_id after rdma_destroy_id checks for one.

Instead, we can replace the use of the global lock around the check to
the rdma_cm_id device pointer by setting the id state to destroying,
then flushing all active callbacks.  The latter is accomplished by
acquiring and releasing the handler_mutex.  Any active handler will
complete first, and any newly scheduled handlers will find the
rdma_cm_id in an invalid state.

In addition to optimizing the current locking scheme, the use of the
rdma_cm_id mutex is a more intuitive synchronization mechanism than
that of the global lock.  These changes are based on feedback from
Doug Ledford <dledford@redhat.com> while he was trying to debug a
crash in the rdma cm destroy path.

Signed-off-by: default avatarSean Hefty <sean.hefty@intel.com>
Signed-off-by: default avatarRoland Dreier <roland@purestorage.com>
parent 8d8ac865

drivers/infiniband/core/cma.c

+16 −27
Original line number Diff line number Diff line
@@ -308,11 +308,13 @@ static inline void release_mc(struct kref *kref) 
	kfree(mc);

}



static void cma_detach_from_dev(struct rdma_id_private *id_priv)

static void cma_release_dev(struct rdma_id_private *id_priv)

{

	mutex_lock(&lock);

	list_del(&id_priv->list);

	cma_deref_dev(id_priv->cma_dev);

	id_priv->cma_dev = NULL;

	mutex_unlock(&lock);

}



static int cma_set_qkey(struct rdma_id_private *id_priv)
@@ -373,6 +375,7 @@ static int cma_acquire_dev(struct rdma_id_private *id_priv) 
	enum rdma_link_layer dev_ll = dev_addr->dev_type == ARPHRD_INFINIBAND ?

		IB_LINK_LAYER_INFINIBAND : IB_LINK_LAYER_ETHERNET;



	mutex_lock(&lock);

	iboe_addr_get_sgid(dev_addr, &iboe_gid);

	memcpy(&gid, dev_addr->src_dev_addr +

	       rdma_addr_gid_offset(dev_addr), sizeof gid);
@@ -398,6 +401,7 @@ out: 
	if (!ret)

		cma_attach_to_dev(id_priv, cma_dev);



	mutex_unlock(&lock);

	return ret;

}
@@ -904,9 +908,14 @@ void rdma_destroy_id(struct rdma_cm_id *id) 
	state = cma_exch(id_priv, CMA_DESTROYING);

	cma_cancel_operation(id_priv, state);



	mutex_lock(&lock);

	/*

	 * Wait for any active callback to finish.  New callbacks will find

	 * the id_priv state set to destroying and abort.

	 */

	mutex_lock(&id_priv->handler_mutex);

	mutex_unlock(&id_priv->handler_mutex);



	if (id_priv->cma_dev) {

		mutex_unlock(&lock);

		switch (rdma_node_get_transport(id_priv->id.device->node_type)) {

		case RDMA_TRANSPORT_IB:

			if (id_priv->cm_id.ib && !IS_ERR(id_priv->cm_id.ib))
@@ -920,10 +929,8 @@ void rdma_destroy_id(struct rdma_cm_id *id) 
			break;

		}

		cma_leave_mc_groups(id_priv);

		mutex_lock(&lock);

		cma_detach_from_dev(id_priv);

		cma_release_dev(id_priv);

	}

	mutex_unlock(&lock);



	cma_release_port(id_priv);

	cma_deref_id(id_priv);
@@ -1200,9 +1207,7 @@ static int cma_req_handler(struct ib_cm_id *cm_id, struct ib_cm_event *ib_event) 
	}



	mutex_lock_nested(&conn_id->handler_mutex, SINGLE_DEPTH_NESTING);

	mutex_lock(&lock);

	ret = cma_acquire_dev(conn_id);

	mutex_unlock(&lock);

	if (ret)

		goto release_conn_id;
@@ -1401,9 +1406,7 @@ static int iw_conn_req_handler(struct iw_cm_id *cm_id, 
		goto out;

	}



	mutex_lock(&lock);

	ret = cma_acquire_dev(conn_id);

	mutex_unlock(&lock);

	if (ret) {

		mutex_unlock(&conn_id->handler_mutex);

		rdma_destroy_id(new_cm_id);
@@ -1966,20 +1969,11 @@ static void addr_handler(int status, struct sockaddr *src_addr, 


	memset(&event, 0, sizeof event);

	mutex_lock(&id_priv->handler_mutex);



	/*

	 * Grab mutex to block rdma_destroy_id() from removing the device while

	 * we're trying to acquire it.

	 */

	mutex_lock(&lock);

	if (!cma_comp_exch(id_priv, CMA_ADDR_QUERY, CMA_ADDR_RESOLVED)) {

		mutex_unlock(&lock);

	if (!cma_comp_exch(id_priv, CMA_ADDR_QUERY, CMA_ADDR_RESOLVED))

		goto out;

	}



	if (!status && !id_priv->cma_dev)

		status = cma_acquire_dev(id_priv);

	mutex_unlock(&lock);



	if (status) {

		if (!cma_comp_exch(id_priv, CMA_ADDR_RESOLVED, CMA_ADDR_BOUND))
@@ -2280,9 +2274,7 @@ int rdma_bind_addr(struct rdma_cm_id *id, struct sockaddr *addr) 
		if (ret)

			goto err1;



		mutex_lock(&lock);

		ret = cma_acquire_dev(id_priv);

		mutex_unlock(&lock);

		if (ret)

			goto err1;

	}
@@ -2294,11 +2286,8 @@ int rdma_bind_addr(struct rdma_cm_id *id, struct sockaddr *addr) 


	return 0;

err2:

	if (id_priv->cma_dev) {

		mutex_lock(&lock);

		cma_detach_from_dev(id_priv);

		mutex_unlock(&lock);

	}

	if (id_priv->cma_dev)

		cma_release_dev(id_priv);

err1:

	cma_comp_exch(id_priv, CMA_ADDR_BOUND, CMA_IDLE);

	return ret;

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