netdev - Re: [patch net-next v4 8/9] devlink: add a command to set notification filter and use it for multicasts

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Message-ID: <98ece061-f21d-bc21-815a-19f34584f268@intel.com>
Date: Mon, 27 Nov 2023 13:30:04 +0100
From: Przemek Kitszel <przemyslaw.kitszel@...el.com>
To: Jiri Pirko <jiri@...nulli.us>, <netdev@...r.kernel.org>
CC: <kuba@...nel.org>, <pabeni@...hat.com>, <davem@...emloft.net>,
	<edumazet@...gle.com>, <jacob.e.keller@...el.com>, <jhs@...atatu.com>,
	<johannes@...solutions.net>, <andriy.shevchenko@...ux.intel.com>,
	<amritha.nambiar@...el.com>, <sdf@...gle.com>, <horms@...nel.org>
Subject: Re: [patch net-next v4 8/9] devlink: add a command to set
 notification filter and use it for multicasts

On 11/23/23 19:15, Jiri Pirko wrote:
> From: Jiri Pirko <jiri@...dia.com>
> 
> Currently the user listening on a socket for devlink notifications
> gets always all messages for all existing instances, even if he is
> interested only in one of those. That may cause unnecessary overhead
> on setups with thousands of instances present.
> 
> User is currently able to narrow down the devlink objects replies
> to dump commands by specifying select attributes.
> 
> Allow similar approach for notifications. Introduce a new devlink
> NOTIFY_FILTER_SET which the user passes the select attributes. Store
> these per-socket and use them for filtering messages
> during multicast send.
> 
> Signed-off-by: Jiri Pirko <jiri@...dia.com>
> ---
> v3->v4:
> - rebased on top of genl_sk_priv_*() introduction
> ---
>   Documentation/netlink/specs/devlink.yaml | 10 ++++
>   include/uapi/linux/devlink.h             |  2 +
>   net/devlink/devl_internal.h              | 34 ++++++++++-
>   net/devlink/netlink.c                    | 73 ++++++++++++++++++++++++
>   net/devlink/netlink_gen.c                | 15 ++++-
>   net/devlink/netlink_gen.h                |  4 +-
>   tools/net/ynl/generated/devlink-user.c   | 31 ++++++++++
>   tools/net/ynl/generated/devlink-user.h   | 47 +++++++++++++++
>   8 files changed, 212 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/netlink/specs/devlink.yaml b/Documentation/netlink/specs/devlink.yaml
> index 43067e1f63aa..6bad1d3454b7 100644
> --- a/Documentation/netlink/specs/devlink.yaml
> +++ b/Documentation/netlink/specs/devlink.yaml
> @@ -2055,3 +2055,13 @@ operations:
>               - bus-name
>               - dev-name
>               - selftests
> +
> +    -
> +      name: notify-filter-set
> +      doc: Set notification messages socket filter.
> +      attribute-set: devlink
> +      do:
> +        request:
> +          attributes:
> +            - bus-name
> +            - dev-name
> diff --git a/include/uapi/linux/devlink.h b/include/uapi/linux/devlink.h
> index b3c8383d342d..130cae0d3e20 100644
> --- a/include/uapi/linux/devlink.h
> +++ b/include/uapi/linux/devlink.h
> @@ -139,6 +139,8 @@ enum devlink_command {
>   	DEVLINK_CMD_SELFTESTS_GET,	/* can dump */
>   	DEVLINK_CMD_SELFTESTS_RUN,
>   
> +	DEVLINK_CMD_NOTIFY_FILTER_SET,
> +
>   	/* add new commands above here */
>   	__DEVLINK_CMD_MAX,
>   	DEVLINK_CMD_MAX = __DEVLINK_CMD_MAX - 1
> diff --git a/net/devlink/devl_internal.h b/net/devlink/devl_internal.h
> index 84dc9628d3f2..82e0fb3bbebf 100644
> --- a/net/devlink/devl_internal.h
> +++ b/net/devlink/devl_internal.h
> @@ -191,11 +191,41 @@ static inline bool devlink_nl_notify_need(struct devlink *devlink)
>   				  DEVLINK_MCGRP_CONFIG);
>   }
>   
> +struct devlink_obj_desc {
> +	struct rcu_head rcu;
> +	const char *bus_name;
> +	const char *dev_name;
> +	long data[];

could you please remove that data pointer?,
you are not using desc as flex pointer as of now

> +};
> +
> +static inline void devlink_nl_obj_desc_init(struct devlink_obj_desc *desc,

given next patch of the series with port index, you could rename this
function to devlink_nl_obj_desc_names_set(), and move 0-init outside.

> +					    struct devlink *devlink)
> +{
> +	memset(desc, 0, sizeof(*desc));
> +	desc->bus_name = devlink->dev->bus->name;
> +	desc->dev_name = dev_name(devlink->dev);
> +}
> +
> +int devlink_nl_notify_filter(struct sock *dsk, struct sk_buff *skb, void *data);
> +
> +static inline void devlink_nl_notify_send_desc(struct devlink *devlink,
> +					       struct sk_buff *msg,
> +					       struct devlink_obj_desc *desc)
> +{
> +	genlmsg_multicast_netns_filtered(&devlink_nl_family,
> +					 devlink_net(devlink),
> +					 msg, 0, DEVLINK_MCGRP_CONFIG,
> +					 GFP_KERNEL,
> +					 devlink_nl_notify_filter, desc);
> +}
> +
>   static inline void devlink_nl_notify_send(struct devlink *devlink,
>   					  struct sk_buff *msg)
>   {
> -	genlmsg_multicast_netns(&devlink_nl_family, devlink_net(devlink),
> -				msg, 0, DEVLINK_MCGRP_CONFIG, GFP_KERNEL);
> +	struct devlink_obj_desc desc;

`= {};` would wipe out the need for memset().

> +
> +	devlink_nl_obj_desc_init(&desc, devlink);
> +	devlink_nl_notify_send_desc(devlink, msg, &desc);
>   }
>   
>   /* Notify */

[snip]