Re: [PATCH v2 02/16] rpmsg: add RPMsg control API to register service

[Mathieu Poirier]

On Tue, Dec 22, 2020 at 11:57:12AM +0100, Arnaud Pouliquen wrote:
> Add API to register a RPMsg service to the control device.
> The rpmsg_drv_ctrl_info structure links a service to its driver.
> 
> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@xxxxxxxxxxx>
> ---
>  drivers/rpmsg/rpmsg_ctrl.c | 57 ++++++++++++++++++++++++++++++++++++++
>  include/linux/rpmsg.h      | 31 +++++++++++++++++++++
>  include/uapi/linux/rpmsg.h | 14 ++++++++++
>  3 files changed, 102 insertions(+)
> 
> diff --git a/drivers/rpmsg/rpmsg_ctrl.c b/drivers/rpmsg/rpmsg_ctrl.c
> index 425c3e32ada4..065e2e304019 100644
> --- a/drivers/rpmsg/rpmsg_ctrl.c
> +++ b/drivers/rpmsg/rpmsg_ctrl.c
> @@ -27,6 +27,20 @@ struct rpmsg_ctrl_dev {
>  	struct device dev;
>  };
>  
> +/**
> + * struct rpmsg_ctl_info - control info list node
> + * @ctrl:	control driver info
> + * @node:	list node
> + *
> + * This structure is used by rpmsg_ctl to list the registered drivers services
> + */
> +struct rpmsg_ctl_info {

struct rpmsg_ctrl_info

> +	const struct rpmsg_drv_ctrl_info *ctrl;
> +	struct list_head node;
> +};
> +
> +static LIST_HEAD(rpmsg_drv_list);
> +
>  static DEFINE_IDA(rpmsg_ctrl_ida);
>  static DEFINE_IDA(rpmsg_minor_ida);
>  
> @@ -175,6 +189,49 @@ static struct rpmsg_driver rpmsg_ctrl_driver = {
>  	.remove = rpmsg_ctrl_remove,
>  };
>  
> +/**
> + * rpmsg_ctrl_register_ctl() -register control for the associated service
> + * @ctrl: rpmsg driver information
> + *
> + * This function is called by the rpmsg driver to register a service that will
> + * be exposed to be instantiate by the application.
> + */
> +int  rpmsg_ctrl_register_ctl(const struct rpmsg_drv_ctrl_info *ctrl)

Here an rpmsg_drv is registered with the infrastructure and as such I propose
rpmsg_ctrl_register_driver_ctrl().

> +{
> +	struct rpmsg_ctl_info *drv_info;
> +
> +	drv_info =  kzalloc(sizeof(*drv_info), GFP_KERNEL);
> +	if (!drv_info)
> +		return -ENOMEM;

When this driver is remove all drv_info left in rpmsg_drv_list should be free'd.
We can't count on users to call rpmsg_ctrl_unregister_ctl().

> +
> +	drv_info->ctrl = ctrl;

This has the potential of creating problems - we don't know then the memory
assocaited with @ctrl will disappear on us.

> +
> +	list_add_tail(&drv_info->node, &rpmsg_drv_list);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(rpmsg_ctrl_register_ctl);
> +
> +/**
> + * rpmsg_ctrl_unregister_ctl() -unregister control for the associated service
> + * @ctrl: the rpmsg control information
> + *
> + * This function is called by the rpmsg driver to unregister the associated
> + * service.
> + */
> +void rpmsg_ctrl_unregister_ctl(const struct rpmsg_drv_ctrl_info *ctrl)
> +{
> +	struct rpmsg_ctl_info *drv_info, *tmp;
> +
> +	list_for_each_entry_safe(drv_info, tmp, &rpmsg_drv_list, node) {
> +		if (drv_info->ctrl == ctrl) {
> +			list_del(&drv_info->node);
> +			kfree(drv_info);
> +		}
> +	}
> +}
> +EXPORT_SYMBOL(rpmsg_ctrl_unregister_ctl);
> +
>  static int rpmsg_ctrl_init(void)
>  {
>  	int ret;
> diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h
> index a5db828b2420..5d64704c2346 100644
> --- a/include/linux/rpmsg.h
> +++ b/include/linux/rpmsg.h
> @@ -26,6 +26,19 @@ struct rpmsg_endpoint;
>  struct rpmsg_device_ops;
>  struct rpmsg_endpoint_ops;
>  
> +/**
> + * struct rpmsg_drv_ctrl_info - rpmsg ctrl structure
> + * @drv_name:	name of the associated driver
> + * @service:	the associated rpmsg service listed in @rpmsg_services
> + *
> + * This structure is used by rpmsg_ctl to link the endpoint creation to the
> + * service rpmsg driver.
> + */
> +struct rpmsg_drv_ctrl_info {
> +	const char *drv_name;
> +	u32  service;
> +};
> +
>  /**
>   * struct rpmsg_channel_info - channel info representation
>   * @name: name of service
> @@ -315,4 +328,22 @@ static inline __poll_t rpmsg_poll(struct rpmsg_endpoint *ept,
>  	module_driver(__rpmsg_driver, register_rpmsg_driver, \
>  			unregister_rpmsg_driver)
>  
> +#if IS_ENABLED(CONFIG_RPMSG_CTRL)
> +
> +int  rpmsg_ctrl_register_ctl(const struct rpmsg_drv_ctrl_info *ctrl);
> +void rpmsg_ctrl_unregister_ctl(const struct rpmsg_drv_ctrl_info *ctrl);
> +
> +#else
> +
> +static inline int rpmsg_ctrl_register_ctl(const struct rpmsg_drv_ctrl_info *ctrl)
> +{
> +	return 0;
> +}
> +
> +static inline void rpmsg_ctrl_unregister_ctl(const struct rpmsg_drv_ctrl_info *ctrl)
> +{
> +}
> +
> +#endif /* IS_ENABLED(CONFIG_RPMSG_CTRL) */

Shouldn't this be in its own header, something like rpmsg_ctrl.h?

> +
>  #endif /* _LINUX_RPMSG_H */
> diff --git a/include/uapi/linux/rpmsg.h b/include/uapi/linux/rpmsg.h
> index e14c6dab4223..0b0cb028e0b3 100644
> --- a/include/uapi/linux/rpmsg.h
> +++ b/include/uapi/linux/rpmsg.h
> @@ -9,6 +9,20 @@
>  #include <linux/ioctl.h>
>  #include <linux/types.h>
>  
> +/**
> + * enum rpmsg_services - list of supported RPMsg services
> + *
> + * @RPMSG_RAW_SERVICE: char device RPMSG service
> + * @RPMSG_START_PRIVATE_SERVICES: private services have to be declared after.
> + */
> +enum rpmsg_services {
> +	/* Reserved services */
> +	RPMSG_RAW_SERVICE =  0,
> +
> +	/* Private services */
> +	RPMSG_START_PRIVATE_SERVICES =  1024,

We have plenty of bits in an enum type - I would set this to 4096 just to be on
the safe side.

> +};
> +
>  /**
>   * struct rpmsg_endpoint_info - endpoint info representation
>   * @name: name of service
> -- 
> 2.17.1
>