Subject: Re: [PATCH net-next 07/11] netdev: expose DPLL pin handle for netdevice

From: Vadim Fedorenko <[email-masked]>
Date: Tue, 1 Aug 2023 14:23:26 +0100

On 20/07/2023 10:18, Vadim Fedorenko wrote:
> From: Jiri Pirko <[email-masked]>
> 
> In case netdevice represents a SyncE port, the user needs to understand
> the connection between netdevice and associated DPLL pin. There might me
> multiple netdevices pointing to the same pin, in case of VF/SF
> implementation.
> 
> Add a IFLA Netlink attribute to nest the DPLL pin handle, similar to
> how it is implemented for devlink port. Add a struct dpll_pin pointer
> to netdev and protect access to it by RTNL. Expose netdev_dpll_pin_set()
> and netdev_dpll_pin_clear() helpers to the drivers so they can set/clear
> the DPLL pin relationship to netdev.
> 
> Note that during the lifetime of struct dpll_pin the pin handle does not
> change. Therefore it is save to access it lockless. It is drivers
> responsibility to call netdev_dpll_pin_clear() before dpll_pin_put().
> 
> Signed-off-by: Jiri Pirko <[email-masked]>
> Signed-off-by: Arkadiusz Kubalewski <[email-masked]>
> Signed-off-by: Vadim Fedorenko <[email-masked]>
> ---
> RFC v9->v0:
> - rearrange function definition according to usage
> v8->v9:
> - net_device->dpll_pin is only valid if IS_ENABLED(CONFIG_DPLL) fix the
>    code in net/core/rtnetlink.c to respect that.
> - move dpll_msg_add_pin_handle to "dpll: netlink" patch + export the
>    function with this patch
> 
>   drivers/dpll/dpll_netlink.c  | 19 ++++++++++++++++---
>   include/linux/dpll.h         | 20 ++++++++++++++++++++
>   include/linux/netdevice.h    | 20 ++++++++++++++++++++
>   include/uapi/linux/if_link.h |  2 ++
>   net/core/dev.c               | 22 ++++++++++++++++++++++
>   net/core/rtnetlink.c         | 35 +++++++++++++++++++++++++++++++++++
>   6 files changed, 115 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/dpll/dpll_netlink.c b/drivers/dpll/dpll_netlink.c
> index c44dda78737d..e4a9bd767b92 100644
> --- a/drivers/dpll/dpll_netlink.c
> +++ b/drivers/dpll/dpll_netlink.c
> @@ -37,6 +37,18 @@ dpll_msg_add_dev_handle(struct sk_buff *msg, struct dpll_device *dpll)
>   	return 0;
>   }
>   
> +/**
> + * dpll_msg_pin_handle_size - get size of pin handle attribute for given pin
> + * @pin: pin pointer
> + *
> + * Return: byte size of pin handle attribute for given pin.
> + */
> +size_t dpll_msg_pin_handle_size(struct dpll_pin *pin)
> +{
> +	return pin ? nla_total_size(4) : 0; /* DPLL_A_PIN_ID */
> +}
> +EXPORT_SYMBOL_GPL(dpll_msg_pin_handle_size);
> +
>   /**
>    * dpll_msg_add_pin_handle - attach pin handle attribute to a given message
>    * @msg: pointer to sk_buff message to attach a pin handle
> @@ -54,6 +66,7 @@ int dpll_msg_add_pin_handle(struct sk_buff *msg, struct dpll_pin *pin)
>   		return -EMSGSIZE;
>   	return 0;
>   }
> +EXPORT_SYMBOL_GPL(dpll_msg_add_pin_handle);

Jiri, could you please remind me what is the reason to export this 
function? Because I cannot
any usage of this function in drivers.

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