Re: [PATCH v1 1/2] soc: qcom: rmtfs-mem: Add class to enable uevents

From: Brian Norris
Date: Thu Dec 20 2018 - 20:19:05 EST


Hi Evan,

On Mon, Dec 17, 2018 at 04:08:33PM -0800, Evan Green wrote:
> Currently the qcom_rmtfs_memN devices are entirely invisible to the udev world.
> Add a class to the rmtfs device so that uevents fire when the device is added.
>
> Signed-off-by: Evan Green <evgreen@xxxxxxxxxxxx>
> ---
>
> drivers/soc/qcom/rmtfs_mem.c | 23 ++++++++++++++++++-----
> 1 file changed, 18 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/soc/qcom/rmtfs_mem.c b/drivers/soc/qcom/rmtfs_mem.c
> index 97bb5989aa211..0bf800ee2a978 100644
> --- a/drivers/soc/qcom/rmtfs_mem.c
> +++ b/drivers/soc/qcom/rmtfs_mem.c
> @@ -132,6 +132,11 @@ static int qcom_rmtfs_mem_release(struct inode *inode, struct file *filp)
> return 0;
> }
>
> +static struct class rmtfs_class = {
> + .owner = THIS_MODULE,
> + .name = "rmtfs",
> +};
> +
> static const struct file_operations qcom_rmtfs_mem_fops = {
> .owner = THIS_MODULE,
> .open = qcom_rmtfs_mem_open,
> @@ -173,9 +178,15 @@ static int qcom_rmtfs_mem_probe(struct platform_device *pdev)
>
> }
>
> + ret = class_register(&rmtfs_class);
> + if (ret)
> + return ret;

Hmm, is this how classes are supposed to work? Usually, you have the
possibility of more than 1 device per class, and therefore you don't
register the class in the driver probe -- you register it in the init()
routine, or something similar. As it is, I expect this will break if
there were ever a second rmtfs device.

Brian

> +
> rmtfs_mem = kzalloc(sizeof(*rmtfs_mem), GFP_KERNEL);
> - if (!rmtfs_mem)
> - return -ENOMEM;
> + if (!rmtfs_mem) {
> + ret = -ENOMEM;
> + goto unregister_class;
> + }
>
> rmtfs_mem->addr = rmem->base;
> rmtfs_mem->client_id = client_id;
> @@ -199,8 +210,8 @@ static int qcom_rmtfs_mem_probe(struct platform_device *pdev)
>
> dev_set_name(&rmtfs_mem->dev, "qcom_rmtfs_mem%d", client_id);
> rmtfs_mem->dev.id = client_id;
> + rmtfs_mem->dev.class = &rmtfs_class;
> rmtfs_mem->dev.devt = MKDEV(MAJOR(qcom_rmtfs_mem_major), client_id);
> -
> ret = cdev_device_add(&rmtfs_mem->cdev, &rmtfs_mem->dev);
> if (ret) {
> dev_err(&pdev->dev, "failed to add cdev: %d\n", ret);
> @@ -235,11 +246,13 @@ static int qcom_rmtfs_mem_probe(struct platform_device *pdev)
>
> return 0;
>
> +
> remove_cdev:
> cdev_device_del(&rmtfs_mem->cdev, &rmtfs_mem->dev);
> put_device:
> put_device(&rmtfs_mem->dev);
> -
> +unregister_class:
> + class_unregister(&rmtfs_class);
> return ret;
> }
>
> @@ -258,7 +271,7 @@ static int qcom_rmtfs_mem_remove(struct platform_device *pdev)
>
> cdev_device_del(&rmtfs_mem->cdev, &rmtfs_mem->dev);
> put_device(&rmtfs_mem->dev);
> -
> + class_unregister(&rmtfs_class);
> return 0;
> }
>
> --
> 2.18.1
>