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Commit 32fd90c4 authored by Christoph Hellwig's avatar Christoph Hellwig
Browse files

nvme: change locking for the per-subsystem controller list 



Life becomes a lot simpler if we just use the global
nvme_subsystems_lock to protect this list.  Given that it is only
accessed during controller probing and removal that isn't a scalability
problem either.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarChaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: default avatarHannes Reinecke <hare@suse.com>
parent 521cfb8e

drivers/nvme/host/core.c

+14 −18
Original line number Diff line number Diff line
@@ -2346,13 +2346,13 @@ static int nvme_active_ctrls(struct nvme_subsystem *subsys) 
	int count = 0;

	struct nvme_ctrl *ctrl;



	mutex_lock(&subsys->lock);

	lockdep_assert_held(&nvme_subsystems_lock);



	list_for_each_entry(ctrl, &subsys->ctrls, subsys_entry) {

		if (ctrl->state != NVME_CTRL_DELETING &&

		    ctrl->state != NVME_CTRL_DEAD)

			count++;

	}

	mutex_unlock(&subsys->lock);



	return count;

}
@@ -2394,6 +2394,9 @@ static int nvme_init_subsystem(struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id) 
	mutex_lock(&nvme_subsystems_lock);

	found = __nvme_find_get_subsystem(subsys->subnqn);

	if (found) {

		__nvme_release_subsystem(subsys);

		subsys = found;



		/*

		 * Verify that the subsystem actually supports multiple

		 * controllers, else bail out.
@@ -2402,14 +2405,10 @@ static int nvme_init_subsystem(struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id) 
		    nvme_active_ctrls(found) && !(id->cmic & (1 << 1))) {

			dev_err(ctrl->device,

				"ignoring ctrl due to duplicate subnqn (%s).\n",

				found->subnqn);

			nvme_put_subsystem(found);

				subsys->subnqn);

			ret = -EINVAL;

			goto out_unlock;

			goto out_put_subsystem;

		}



		__nvme_release_subsystem(subsys);

		subsys = found;

	} else {

		ret = device_add(&subsys->dev);

		if (ret) {
@@ -2421,23 +2420,20 @@ static int nvme_init_subsystem(struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id) 
		list_add_tail(&subsys->entry, &nvme_subsystems);

	}



	ctrl->subsys = subsys;

	mutex_unlock(&nvme_subsystems_lock);



	if (sysfs_create_link(&subsys->dev.kobj, &ctrl->device->kobj,

			dev_name(ctrl->device))) {

		dev_err(ctrl->device,

			"failed to create sysfs link from subsystem.\n");

		/* the transport driver will eventually put the subsystem */

		return -EINVAL;

		goto out_put_subsystem;

	}



	mutex_lock(&subsys->lock);

	ctrl->subsys = subsys;

	list_add_tail(&ctrl->subsys_entry, &subsys->ctrls);

	mutex_unlock(&subsys->lock);



	mutex_unlock(&nvme_subsystems_lock);

	return 0;



out_put_subsystem:

	nvme_put_subsystem(subsys);

out_unlock:

	mutex_unlock(&nvme_subsystems_lock);

	put_device(&subsys->dev);
@@ -3694,10 +3690,10 @@ static void nvme_free_ctrl(struct device *dev) 
	__free_page(ctrl->discard_page);



	if (subsys) {

		mutex_lock(&subsys->lock);

		mutex_lock(&nvme_subsystems_lock);

		list_del(&ctrl->subsys_entry);

		mutex_unlock(&subsys->lock);

		sysfs_remove_link(&subsys->dev.kobj, dev_name(ctrl->device));

		mutex_unlock(&nvme_subsystems_lock);

	}



	ctrl->ops->free_ctrl(ctrl);