[PATCH 2/3] nvme: move get/put ctrl into dev open/release

[Logan Gunthorpe]

On 2020-09-03 8:39 p.m., Chaitanya Kulkarni wrote:
> Introduce nvme_dev_release ctrl file release callback and move ctrl get
> and put operations from target passthru into host core in ctrl open and
> release file operations respectively. This is needed to atomically
> get/put ctrl and get/put ctrl module refcount without using any locks.
> 
> Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni at wdc.com>
> ---
>  drivers/nvme/host/core.c       | 12 +++++++++++-
>  drivers/nvme/target/passthru.c |  7 ++-----
>  2 files changed, 13 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index fa7c0def9184..a1707afcb710 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -3262,6 +3262,16 @@ static int nvme_dev_open(struct inode *inode, struct file *file)
>  	}
>  
>  	file->private_data = ctrl;
> +	nvme_get_ctrl(ctrl);
> +	return 0;
> +}
> +
> +static int nvme_dev_release(struct inode *inode, struct file *file)
> +{
> +	struct nvme_ctrl *ctrl =
> +		container_of(inode->i_cdev, struct nvme_ctrl, cdev);
> +
> +	nvme_put_ctrl(ctrl);
>  	return 0;
>  }
>  
> @@ -3327,6 +3337,7 @@ static long nvme_dev_ioctl(struct file *file, unsigned int cmd,
>  static const struct file_operations nvme_dev_fops = {
>  	.owner		= THIS_MODULE,
>  	.open		= nvme_dev_open,
> +	.release	= nvme_dev_release,
>  	.unlocked_ioctl	= nvme_dev_ioctl,
>  	.compat_ioctl	= compat_ptr_ioctl,
>  };

Once again, above this makes sense. Below this seems very much unrelated.



> @@ -4651,7 +4662,6 @@ struct nvme_ctrl *nvme_ctrl_get_by_file(struct file *f)
>  	}
>  
>  	ctrl = f->private_data;
> -	nvme_get_ctrl(ctrl);
>  
>  out_close:
>  	return ctrl;
> diff --git a/drivers/nvme/target/passthru.c b/drivers/nvme/target/passthru.c
> index 14a842408035..9cd8fd2ddc72 100644
> --- a/drivers/nvme/target/passthru.c
> +++ b/drivers/nvme/target/passthru.c
> @@ -507,11 +507,11 @@ int nvmet_passthru_ctrl_enable(struct nvmet_subsys *subsys)
>  			 subsys, GFP_KERNEL);
>  	if (xa_is_err(old)) {
>  		ret = xa_err(old);
> -		goto out_put_ctrl;
> +		goto out_put_file;
>  	}
>  
>  	if (old)
> -		goto out_put_ctrl;
> +		goto out_put_file;
>  
>  	subsys->passthru_ctrl = ctrl;
>  	subsys->ver = ctrl->vs;
> @@ -526,8 +526,6 @@ int nvmet_passthru_ctrl_enable(struct nvmet_subsys *subsys)
>  	mutex_unlock(&subsys->lock);
>  	return 0;
>  
> -out_put_ctrl:
> -	nvme_put_ctrl(ctrl);
>  out_put_file:
>  	filp_close(subsys->passthru_ctrl_file, NULL);
>  out_unlock:
> @@ -540,7 +538,6 @@ static void __nvmet_passthru_ctrl_disable(struct nvmet_subsys *subsys)
>  	if (subsys->passthru_ctrl) {
>  		xa_erase(&passthru_subsystems, subsys->passthru_ctrl->cntlid);
>  		filp_close(subsys->passthru_ctrl_file, NULL);
> -		nvme_put_ctrl(subsys->passthru_ctrl);
>  	}
>  	subsys->passthru_ctrl = NULL;
>  	subsys->ver = NVMET_DEFAULT_VS;
>