netdev - [patch net-next v2 2/7] devlink: make sure driver does not read updated driverinit param before reload

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Date:   Fri, 10 Feb 2023 11:01:26 +0100
From:   Jiri Pirko <jiri@...nulli.us>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com,
        edumazet@...gle.com, tariqt@...dia.com, saeedm@...dia.com,
        jacob.e.keller@...el.com, gal@...dia.com, kim.phillips@....com,
        moshe@...dia.com, simon.horman@...igine.com, idosch@...dia.com
Subject: [patch net-next v2 2/7] devlink: make sure driver does not read updated driverinit param before reload

From: Jiri Pirko <jiri@...dia.com>

The driverinit param purpose is to serve the driver during init/reload
time to provide a value, either default or set by user.

Make sure that driver does not read value updated by user before the
reload is performed. Hold the new value in a separate struct and switch
it during reload.

Note that this is required to be eventually possible to call
devl_param_driverinit_value_get() without holding instance lock.

Signed-off-by: Jiri Pirko <jiri@...dia.com>
---
v1->v2:
- extended patch description with a note
- call driverinit_load_new only if action is REINIT
---
 include/net/devlink.h       |  4 ++++
 net/devlink/dev.c           |  3 +++
 net/devlink/devl_internal.h |  3 +++
 net/devlink/leftover.c      | 26 ++++++++++++++++++++++----
 4 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/include/net/devlink.h b/include/net/devlink.h
index 2e85a5970a32..8ed960345f37 100644
--- a/include/net/devlink.h
+++ b/include/net/devlink.h
@@ -489,6 +489,10 @@ struct devlink_param_item {
 	const struct devlink_param *param;
 	union devlink_param_value driverinit_value;
 	bool driverinit_value_valid;
+	union devlink_param_value driverinit_value_new; /* Not reachable
+							 * until reload.
+							 */
+	bool driverinit_value_new_valid;
 };
 
 enum devlink_param_generic_id {
diff --git a/net/devlink/dev.c b/net/devlink/dev.c
index 78d824eda5ec..f995d88b9d04 100644
--- a/net/devlink/dev.c
+++ b/net/devlink/dev.c
@@ -369,6 +369,9 @@ int devlink_reload(struct devlink *devlink, struct net *dest_net,
 	if (dest_net && !net_eq(dest_net, curr_net))
 		devlink_reload_netns_change(devlink, curr_net, dest_net);
 
+	if (action == DEVLINK_RELOAD_ACTION_DRIVER_REINIT)
+		devlink_params_driverinit_load_new(devlink);
+
 	err = devlink->ops->reload_up(devlink, action, limit, actions_performed, extack);
 	devlink_reload_failed_set(devlink, !!err);
 	if (err)
diff --git a/net/devlink/devl_internal.h b/net/devlink/devl_internal.h
index 941174e157d4..5c117e8d4377 100644
--- a/net/devlink/devl_internal.h
+++ b/net/devlink/devl_internal.h
@@ -189,6 +189,9 @@ static inline bool devlink_reload_supported(const struct devlink_ops *ops)
 	return ops->reload_down && ops->reload_up;
 }
 
+/* Params */
+void devlink_params_driverinit_load_new(struct devlink *devlink);
+
 /* Resources */
 struct devlink_resource;
 int devlink_resources_validate(struct devlink *devlink,
diff --git a/net/devlink/leftover.c b/net/devlink/leftover.c
index f2f6a2f42864..61e59556ea03 100644
--- a/net/devlink/leftover.c
+++ b/net/devlink/leftover.c
@@ -4098,9 +4098,12 @@ static int devlink_nl_param_fill(struct sk_buff *msg, struct devlink *devlink,
 		if (!devlink_param_cmode_is_supported(param, i))
 			continue;
 		if (i == DEVLINK_PARAM_CMODE_DRIVERINIT) {
-			if (!param_item->driverinit_value_valid)
+			if (param_item->driverinit_value_new_valid)
+				param_value[i] = param_item->driverinit_value_new;
+			else if (param_item->driverinit_value_valid)
+				param_value[i] = param_item->driverinit_value;
+			else
 				return -EOPNOTSUPP;
-			param_value[i] = param_item->driverinit_value;
 		} else {
 			ctx.cmode = i;
 			err = devlink_param_get(devlink, param, &ctx);
@@ -4388,8 +4391,8 @@ static int __devlink_nl_cmd_param_set_doit(struct devlink *devlink,
 		return -EOPNOTSUPP;
 
 	if (cmode == DEVLINK_PARAM_CMODE_DRIVERINIT) {
-		param_item->driverinit_value = value;
-		param_item->driverinit_value_valid = true;
+		param_item->driverinit_value_new = value;
+		param_item->driverinit_value_new_valid = true;
 	} else {
 		if (!param->set)
 			return -EOPNOTSUPP;
@@ -9691,6 +9694,21 @@ void devl_param_driverinit_value_set(struct devlink *devlink, u32 param_id,
 }
 EXPORT_SYMBOL_GPL(devl_param_driverinit_value_set);
 
+void devlink_params_driverinit_load_new(struct devlink *devlink)
+{
+	struct devlink_param_item *param_item;
+
+	list_for_each_entry(param_item, &devlink->param_list, list) {
+		if (!devlink_param_cmode_is_supported(param_item->param,
+						      DEVLINK_PARAM_CMODE_DRIVERINIT) ||
+		    !param_item->driverinit_value_new_valid)
+			continue;
+		param_item->driverinit_value = param_item->driverinit_value_new;
+		param_item->driverinit_value_valid = true;
+		param_item->driverinit_value_new_valid = false;
+	}
+}
+
 /**
  *	devl_param_value_changed - notify devlink on a parameter's value
  *				   change. Should be called by the driver
-- 
2.39.0