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

Mathieu Poirier
2021-01-21T23:47:07Z

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@foss.st.com>
> ---
> 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
>