Commit 4e2f02bf authored by Leonid Ravich's avatar Leonid Ravich Committed by Christoph Hellwig
Browse files

nvmet-fc: use RCU proctection for assoc_list 



searching assoc_list protected by rcu_read_lock if list not changed inline.
and according to the rcu list rules.

queue array embedded into nvmet_fc_tgt_assoc protected by rcu_read_lock
according to rcu dereference/assign rules.

queue and assoc object freed after grace period by call_rcu.

tgtport lock taken for changing assoc_list.

Reviewed-by: default avatarEldad Zinger <Eldad.Zinger@dell.com>
Reviewed-by: default avatarElad Grupi <Elad.Grupi@dell.com>
Reviewed-by: default avatarJames Smart <james.smart@broadcom.com>
Signed-off-by: default avatarLeonid Ravich <Leonid.Ravich@emc.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent 36ca03c8

drivers/nvme/target/fc.c

+38 −43
Original line number Diff line number Diff line
@@ -145,6 +145,7 @@ struct nvmet_fc_tgt_queue { 
	struct list_head		avail_defer_list;

	struct workqueue_struct		*work_q;

	struct kref			ref;

	struct rcu_head			rcu;

	struct nvmet_fc_fcp_iod		fod[];		/* array of fcp_iods */

} __aligned(sizeof(unsigned long long));
@@ -167,6 +168,7 @@ struct nvmet_fc_tgt_assoc { 
	struct nvmet_fc_tgt_queue	*queues[NVMET_NR_QUEUES + 1];

	struct kref			ref;

	struct work_struct		del_work;

	struct rcu_head			rcu;

};
@@ -790,7 +792,6 @@ nvmet_fc_alloc_target_queue(struct nvmet_fc_tgt_assoc *assoc, 
			u16 qid, u16 sqsize)

{

	struct nvmet_fc_tgt_queue *queue;

	unsigned long flags;

	int ret;



	if (qid > NVMET_NR_QUEUES)
@@ -829,9 +830,7 @@ nvmet_fc_alloc_target_queue(struct nvmet_fc_tgt_assoc *assoc, 
		goto out_fail_iodlist;



	WARN_ON(assoc->queues[qid]);

	spin_lock_irqsave(&assoc->tgtport->lock, flags);

	assoc->queues[qid] = queue;

	spin_unlock_irqrestore(&assoc->tgtport->lock, flags);

	rcu_assign_pointer(assoc->queues[qid], queue);



	return queue;
@@ -851,11 +850,8 @@ nvmet_fc_tgt_queue_free(struct kref *ref) 
{

	struct nvmet_fc_tgt_queue *queue =

		container_of(ref, struct nvmet_fc_tgt_queue, ref);

	unsigned long flags;



	spin_lock_irqsave(&queue->assoc->tgtport->lock, flags);

	queue->assoc->queues[queue->qid] = NULL;

	spin_unlock_irqrestore(&queue->assoc->tgtport->lock, flags);

	rcu_assign_pointer(queue->assoc->queues[queue->qid], NULL);



	nvmet_fc_destroy_fcp_iodlist(queue->assoc->tgtport, queue);
@@ -863,7 +859,7 @@ nvmet_fc_tgt_queue_free(struct kref *ref) 


	destroy_workqueue(queue->work_q);



	kfree(queue);

	kfree_rcu(queue, rcu);

}



static void
@@ -965,24 +961,23 @@ nvmet_fc_find_target_queue(struct nvmet_fc_tgtport *tgtport, 
	struct nvmet_fc_tgt_queue *queue;

	u64 association_id = nvmet_fc_getassociationid(connection_id);

	u16 qid = nvmet_fc_getqueueid(connection_id);

	unsigned long flags;



	if (qid > NVMET_NR_QUEUES)

		return NULL;



	spin_lock_irqsave(&tgtport->lock, flags);

	list_for_each_entry(assoc, &tgtport->assoc_list, a_list) {

	rcu_read_lock();

	list_for_each_entry_rcu(assoc, &tgtport->assoc_list, a_list) {

		if (association_id == assoc->association_id) {

			queue = assoc->queues[qid];

			queue = rcu_dereference(assoc->queues[qid]);

			if (queue &&

			    (!atomic_read(&queue->connected) ||

			     !nvmet_fc_tgt_q_get(queue)))

				queue = NULL;

			spin_unlock_irqrestore(&tgtport->lock, flags);

			rcu_read_unlock();

			return queue;

		}

	}

	spin_unlock_irqrestore(&tgtport->lock, flags);

	rcu_read_unlock();

	return NULL;

}
@@ -1137,7 +1132,7 @@ nvmet_fc_alloc_target_assoc(struct nvmet_fc_tgtport *tgtport, void *hosthandle) 
		}

		if (!needrandom) {

			assoc->association_id = ran;

			list_add_tail(&assoc->a_list, &tgtport->assoc_list);

			list_add_tail_rcu(&assoc->a_list, &tgtport->assoc_list);

		}

		spin_unlock_irqrestore(&tgtport->lock, flags);

	}
@@ -1167,7 +1162,7 @@ nvmet_fc_target_assoc_free(struct kref *ref) 


	nvmet_fc_free_hostport(assoc->hostport);

	spin_lock_irqsave(&tgtport->lock, flags);

	list_del(&assoc->a_list);

	list_del_rcu(&assoc->a_list);

	oldls = assoc->rcv_disconn;

	spin_unlock_irqrestore(&tgtport->lock, flags);

	/* if pending Rcv Disconnect Association LS, send rsp now */
@@ -1177,7 +1172,7 @@ nvmet_fc_target_assoc_free(struct kref *ref) 
	dev_info(tgtport->dev,

		"{%d:%d} Association freed\n",

		tgtport->fc_target_port.port_num, assoc->a_id);

	kfree(assoc);

	kfree_rcu(assoc, rcu);

	nvmet_fc_tgtport_put(tgtport);

}
@@ -1198,7 +1193,6 @@ nvmet_fc_delete_target_assoc(struct nvmet_fc_tgt_assoc *assoc) 
{

	struct nvmet_fc_tgtport *tgtport = assoc->tgtport;

	struct nvmet_fc_tgt_queue *queue;

	unsigned long flags;

	int i, terminating;



	terminating = atomic_xchg(&assoc->terminating, 1);
@@ -1207,19 +1201,23 @@ nvmet_fc_delete_target_assoc(struct nvmet_fc_tgt_assoc *assoc) 
	if (terminating)

		return;



	spin_lock_irqsave(&tgtport->lock, flags);



	for (i = NVMET_NR_QUEUES; i >= 0; i--) {

		queue = assoc->queues[i];

		if (queue) {

			if (!nvmet_fc_tgt_q_get(queue))

		rcu_read_lock();

		queue = rcu_dereference(assoc->queues[i]);

		if (!queue) {

			rcu_read_unlock();

			continue;

			spin_unlock_irqrestore(&tgtport->lock, flags);

		}



		if (!nvmet_fc_tgt_q_get(queue)) {

			rcu_read_unlock();

			continue;

		}

		rcu_read_unlock();

		nvmet_fc_delete_target_queue(queue);

		nvmet_fc_tgt_q_put(queue);

			spin_lock_irqsave(&tgtport->lock, flags);

		}

	}

	spin_unlock_irqrestore(&tgtport->lock, flags);



	dev_info(tgtport->dev,

		"{%d:%d} Association deleted\n",
@@ -1234,10 +1232,9 @@ nvmet_fc_find_target_assoc(struct nvmet_fc_tgtport *tgtport, 
{

	struct nvmet_fc_tgt_assoc *assoc;

	struct nvmet_fc_tgt_assoc *ret = NULL;

	unsigned long flags;



	spin_lock_irqsave(&tgtport->lock, flags);

	list_for_each_entry(assoc, &tgtport->assoc_list, a_list) {

	rcu_read_lock();

	list_for_each_entry_rcu(assoc, &tgtport->assoc_list, a_list) {

		if (association_id == assoc->association_id) {

			ret = assoc;

			if (!nvmet_fc_tgt_a_get(assoc))
@@ -1245,7 +1242,7 @@ nvmet_fc_find_target_assoc(struct nvmet_fc_tgtport *tgtport, 
			break;

		}

	}

	spin_unlock_irqrestore(&tgtport->lock, flags);

	rcu_read_unlock();



	return ret;

}
@@ -1473,19 +1470,17 @@ nvmet_fc_tgtport_get(struct nvmet_fc_tgtport *tgtport) 
static void

__nvmet_fc_free_assocs(struct nvmet_fc_tgtport *tgtport)

{

	struct nvmet_fc_tgt_assoc *assoc, *next;

	unsigned long flags;

	struct nvmet_fc_tgt_assoc *assoc;



	spin_lock_irqsave(&tgtport->lock, flags);

	list_for_each_entry_safe(assoc, next,

				&tgtport->assoc_list, a_list) {

	rcu_read_lock();

	list_for_each_entry_rcu(assoc, &tgtport->assoc_list, a_list) {

		if (!nvmet_fc_tgt_a_get(assoc))

			continue;

		if (!schedule_work(&assoc->del_work))

			/* already deleting - release local reference */

			nvmet_fc_tgt_a_put(assoc);

	}

	spin_unlock_irqrestore(&tgtport->lock, flags);

	rcu_read_unlock();

}



/**
@@ -1568,16 +1563,16 @@ nvmet_fc_delete_ctrl(struct nvmet_ctrl *ctrl) 
			continue;

		spin_unlock_irqrestore(&nvmet_fc_tgtlock, flags);



		spin_lock_irqsave(&tgtport->lock, flags);

		list_for_each_entry(assoc, &tgtport->assoc_list, a_list) {

			queue = assoc->queues[0];

		rcu_read_lock();

		list_for_each_entry_rcu(assoc, &tgtport->assoc_list, a_list) {

			queue = rcu_dereference(assoc->queues[0]);

			if (queue && queue->nvme_sq.ctrl == ctrl) {

				if (nvmet_fc_tgt_a_get(assoc))

					found_ctrl = true;

				break;

			}

		}

		spin_unlock_irqrestore(&tgtport->lock, flags);

		rcu_read_unlock();



		nvmet_fc_tgtport_put(tgtport);