[RFC PATCH v2 2/3] dpll: add netlink events

[Kubalewski, Arkadiusz]

-----Original Message-----
From: Vadim Fedorenko <vfedorenko at novek.ru> 
Sent: Sunday, June 26, 2022 9:25 PM
>
>From: Vadim Fedorenko <vadfed at fb.com>
>
>Add netlink interface to enable notification of users about
>events in DPLL framework. Part of this interface should be
>used by drivers directly, i.e. lock status changes.
>
>Signed-off-by: Vadim Fedorenko <vadfed at fb.com>
>---
> drivers/dpll/dpll_core.c    |   2 +
> drivers/dpll/dpll_netlink.c | 141 ++++++++++++++++++++++++++++++++++++
> drivers/dpll/dpll_netlink.h |   7 ++
> 3 files changed, 150 insertions(+)
>
>diff --git a/drivers/dpll/dpll_core.c b/drivers/dpll/dpll_core.c
>index dc0330e3687d..387644aa910e 100644
>--- a/drivers/dpll/dpll_core.c
>+++ b/drivers/dpll/dpll_core.c
>@@ -97,6 +97,8 @@ struct dpll_device *dpll_device_alloc(struct dpll_device_ops *ops, int sources_c
> 	mutex_unlock(&dpll_device_xa_lock);
> 	dpll->priv = priv;
> 
>+	dpll_notify_device_create(dpll->id, dev_name(&dpll->dev));
>+
> 	return dpll;
> 
> error:
>diff --git a/drivers/dpll/dpll_netlink.c b/drivers/dpll/dpll_netlink.c
>index e15106f30377..4b1684fcf41e 100644
>--- a/drivers/dpll/dpll_netlink.c
>+++ b/drivers/dpll/dpll_netlink.c
>@@ -48,6 +48,8 @@ struct param {
> 	int dpll_source_type;
> 	int dpll_output_id;
> 	int dpll_output_type;
>+	int dpll_status;
>+	const char *dpll_name;
> };
> 
> struct dpll_dump_ctx {
>@@ -239,6 +241,8 @@ static int dpll_genl_cmd_set_source(struct param *p)
> 	ret = dpll->ops->set_source_type(dpll, src_id, type);
> 	mutex_unlock(&dpll->lock);
> 
>+	dpll_notify_source_change(dpll->id, src_id, type);
>+
> 	return ret;
> }
> 
>@@ -262,6 +266,8 @@ static int dpll_genl_cmd_set_output(struct param *p)
> 	ret = dpll->ops->set_source_type(dpll, out_id, type);
> 	mutex_unlock(&dpll->lock);
> 
>+	dpll_notify_source_change(dpll->id, out_id, type);
>+
> 	return ret;
> }
> 
>@@ -438,6 +444,141 @@ static struct genl_family dpll_gnl_family __ro_after_init = {
> 	.pre_doit	= dpll_pre_doit,
> };
> 
>+static int dpll_event_device_create(struct param *p)
>+{
>+	if (nla_put_u32(p->msg, DPLLA_DEVICE_ID, p->dpll_id) ||
>+	    nla_put_string(p->msg, DPLLA_DEVICE_NAME, p->dpll_name))
>+		return -EMSGSIZE;
>+
>+	return 0;
>+}
>+
>+static int dpll_event_device_delete(struct param *p)
>+{
>+	if (nla_put_u32(p->msg, DPLLA_DEVICE_ID, p->dpll_id))
>+		return -EMSGSIZE;
>+
>+	return 0;
>+}
>+
>+static int dpll_event_status(struct param *p)
>+{
>+	if (nla_put_u32(p->msg, DPLLA_DEVICE_ID, p->dpll_id) ||
>+		nla_put_u32(p->msg, DPLLA_LOCK_STATUS, p->dpll_status))
>+		return -EMSGSIZE;
>+
>+	return 0;
>+}
>+
>+static int dpll_event_source_change(struct param *p)
>+{
>+	if (nla_put_u32(p->msg, DPLLA_DEVICE_ID, p->dpll_id) ||
>+	    nla_put_u32(p->msg, DPLLA_SOURCE_ID, p->dpll_source_id) ||
>+		nla_put_u32(p->msg, DPLLA_SOURCE_TYPE, p->dpll_source_type))
>+		return -EMSGSIZE;
>+
>+	return 0;
>+}
>+
>+static int dpll_event_output_change(struct param *p)
>+{
>+	if (nla_put_u32(p->msg, DPLLA_DEVICE_ID, p->dpll_id) ||
>+	    nla_put_u32(p->msg, DPLLA_OUTPUT_ID, p->dpll_output_id) ||
>+		nla_put_u32(p->msg, DPLLA_OUTPUT_TYPE, p->dpll_output_type))
>+		return -EMSGSIZE;
>+
>+	return 0;
>+}
>+
>+static cb_t event_cb[] = {
>+	[DPLL_EVENT_DEVICE_CREATE]	= dpll_event_device_create,
>+	[DPLL_EVENT_DEVICE_DELETE]	= dpll_event_device_delete,
>+	[DPLL_EVENT_STATUS_LOCKED]	= dpll_event_status,
>+	[DPLL_EVENT_STATUS_UNLOCKED]	= dpll_event_status,
>+	[DPLL_EVENT_SOURCE_CHANGE]	= dpll_event_source_change,
>+	[DPLL_EVENT_OUTPUT_CHANGE]	= dpll_event_output_change,
>+};
>+/*
>+ * Generic netlink DPLL event encoding
>+ */
>+static int dpll_send_event(enum dpll_genl_event event,
>+				   struct param *p)
>+{
>+	struct sk_buff *msg;
>+	int ret = -EMSGSIZE;
>+	void *hdr;
>+
>+	msg = genlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
>+	if (!msg)
>+		return -ENOMEM;
>+	p->msg = msg;
>+
>+	hdr = genlmsg_put(msg, 0, 0, &dpll_gnl_family, 0, event);
>+	if (!hdr)
>+		goto out_free_msg;
>+
>+	ret = event_cb[event](p);
>+	if (ret)
>+		goto out_cancel_msg;
>+
>+	genlmsg_end(msg, hdr);
>+
>+	genlmsg_multicast(&dpll_gnl_family, msg, 0, 1, GFP_KERNEL);

All multicasts are send only for group "1" (DPLL_CONFIG_SOURCE_GROUP_NAME),
but 4 groups were defined.
  
>+
>+	return 0;
>+
>+out_cancel_msg:
>+	genlmsg_cancel(msg, hdr);
>+out_free_msg:
>+	nlmsg_free(msg);
>+
>+	return ret;
>+}
>+
>+int dpll_notify_device_create(int dpll_id, const char *name)
>+{
>+	struct param p = { .dpll_id = dpll_id, .dpll_name = name };
>+
>+	return dpll_send_event(DPLL_EVENT_DEVICE_CREATE, &p);
>+}
>+
>+int dpll_notify_device_delete(int dpll_id)
>+{
>+	struct param p = { .dpll_id = dpll_id };
>+
>+	return dpll_send_event(DPLL_EVENT_DEVICE_DELETE, &p);
>+}
>+
>+int dpll_notify_status_locked(int dpll_id)
>+{
>+	struct param p = { .dpll_id = dpll_id, .dpll_status = 1 };
>+
>+	return dpll_send_event(DPLL_EVENT_STATUS_LOCKED, &p);
>+}
>+
>+int dpll_notify_status_unlocked(int dpll_id)
>+{
>+	struct param p = { .dpll_id = dpll_id, .dpll_status = 0 };
>+
>+	return dpll_send_event(DPLL_EVENT_STATUS_UNLOCKED, &p);
>+}
>+
>+int dpll_notify_source_change(int dpll_id, int source_id, int source_type)
>+{
>+	struct param p =  { .dpll_id = dpll_id, .dpll_source_id = source_id,
>+						.dpll_source_type = source_type };
>+
>+	return dpll_send_event(DPLL_EVENT_SOURCE_CHANGE, &p);
>+}
>+
>+int dpll_notify_output_change(int dpll_id, int output_id, int output_type)
>+{
>+	struct param p =  { .dpll_id = dpll_id, .dpll_output_id = output_id,
>+						.dpll_output_type = output_type };
>+
>+	return dpll_send_event(DPLL_EVENT_OUTPUT_CHANGE, &p);
>+}
>+
> int __init dpll_netlink_init(void)
> {
> 	return genl_register_family(&dpll_gnl_family);
>diff --git a/drivers/dpll/dpll_netlink.h b/drivers/dpll/dpll_netlink.h
>index e2d100f59dd6..0dc81320f982 100644
>--- a/drivers/dpll/dpll_netlink.h
>+++ b/drivers/dpll/dpll_netlink.h
>@@ -3,5 +3,12 @@
>  *  Copyright (c) 2021 Meta Platforms, Inc. and affiliates
>  */
> 
>+int dpll_notify_device_create(int dpll_id, const char *name);
>+int dpll_notify_device_delete(int dpll_id);
>+int dpll_notify_status_locked(int dpll_id);
>+int dpll_notify_status_unlocked(int dpll_id);
>+int dpll_notify_source_change(int dpll_id, int source_id, int source_type);
>+int dpll_notify_output_change(int dpll_id, int output_id, int output_type);

Only dpll_notify_device_create is actually used, rest is not.
I am getting confused a bit, who should call those "notify" functions?
It is straightforward for create/delete, dpll subsystem shall do it, but what
about the rest?
I would say notifications about status or source/output change shall originate
in the driver implementing dpll interface, thus they shall be exported and
defined in the header included by the driver.

>+
> int __init dpll_netlink_init(void);
> void dpll_netlink_finish(void);
>-- 
>2.27.0
>