Re: [PATCH net-next 1/2] devlink: Break parameter notification sequence to be before/after unload/load driver

On Thu, Jul 29, 2021 at 01:57:01PM +0200, Jiri Pirko wrote:

Thu, Jul 29, 2021 at 01:35:55PM CEST, leon@kernel.org wrote:

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On Thu, Jul 29, 2021 at 01:22:58PM +0200, Jiri Pirko wrote:

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Thu, Jul 29, 2021 at 10:15:25AM CEST, leon@kernel.org wrote:

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From: Leon Romanovsky <leonro@nvidia.com>

<...>

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diff --git a/net/core/devlink.c b/net/core/devlink.c
index b596a971b473..54e2a0375539 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c

@@ -3801,8 +3801,9 @@ static void devlink_param_notify(struct devlink *devlink,

				 struct devlink_param_item *param_item,
				 enum devlink_command cmd);

-static void devlink_reload_netns_change(struct devlink *devlink,
-					struct net *dest_net)
+static void devlink_params_notify(struct devlink *devlink, struct net *dest_net,

Please name it differently. This function notifies not only the params,
but the devlink instance itself as well.

I'm open for suggestion. What did you have in mind?

devlink_ns_change_notify?

NP, will change 

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+				  struct net *curr_net,
+				  enum devlink_command cmd)
{
	struct devlink_param_item *param_item;

@@ -3812,17 +3813,17 @@ static void devlink_reload_netns_change(struct devlink *devlink,

	 * reload process so the notifications are generated separatelly.
	 */

-	list_for_each_entry(param_item, &devlink->param_list, list)
-		devlink_param_notify(devlink, 0, param_item,
-				     DEVLINK_CMD_PARAM_DEL);
-	devlink_notify(devlink, DEVLINK_CMD_DEL);
+	if (!dest_net || net_eq(dest_net, curr_net))
+		return;

-	__devlink_net_set(devlink, dest_net);
+	if (cmd == DEVLINK_CMD_PARAM_NEW)
+		devlink_notify(devlink, DEVLINK_CMD_NEW);

This is quite odd. According to PARAMS cmd you decife devlink CMD.

Just have bool arg which would help you select both
DEVLINK_CMD_PARAM_NEW/DEL and DEVLINK_CMD_NEW/DEL

The patch is quite misleading, but the final result looks neat:

  3847 static void devlink_params_notify(struct devlink *devlink, struct net *dest_net,
  3848                                   struct net *curr_net,
  3849                                   enum devlink_command cmd)
  3850 {
  3851         struct devlink_param_item *param_item;
  3852 
  3853         /* Userspace needs to be notified about devlink objects
  3854          * removed from original and entering new network namespace.
  3855          * The rest of the devlink objects are re-created during
  3856          * reload process so the notifications are generated separatelly.
  3857          */
  3858 
  3859         if (!dest_net || net_eq(dest_net, curr_net))
  3860                 return;
  3861 
  3862         if (cmd == DEVLINK_CMD_PARAM_NEW)
  3863                 devlink_notify(devlink, DEVLINK_CMD_NEW);

Nothing misleading here. This is exactly what I'm pointing out...

Do you ask for this change?

diff --git a/net/core/devlink.c b/net/core/devlink.c
index 077310c26a8b..ee7204787b29 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c

@@ -3846,7 +3846,7 @@ static void devlink_param_notify(struct devlink *devlink,
 
 static void devlink_params_notify(struct devlink *devlink, struct net *dest_net,
                                  struct net *curr_net,
-                                 enum devlink_command cmd)
+                                 enum devlink_command cmd, bool new)
 {
        struct devlink_param_item *param_item;
 

@@ -3859,13 +3859,13 @@ static void devlink_params_notify(struct devlink *devlink, struct net *dest_net,
        if (!dest_net || net_eq(dest_net, curr_net))
                return;
 
-       if (cmd == DEVLINK_CMD_PARAM_NEW)
+       if (new)
                devlink_notify(devlink, DEVLINK_CMD_NEW);
 
        list_for_each_entry(param_item, &devlink->param_list, list)
                devlink_param_notify(devlink, 0, param_item, cmd);
 
-       if (cmd == DEVLINK_CMD_PARAM_DEL)
+       if (!new)
                devlink_notify(devlink, DEVLINK_CMD_DEL);
 }
 

@@ -3957,7 +3957,7 @@ static int devlink_reload(struct devlink *devlink, struct net *dest_net,
 
        curr_net = devlink_net(devlink);
        devlink_params_notify(devlink, dest_net, curr_net,
-                             DEVLINK_CMD_PARAM_DEL);
+                             DEVLINK_CMD_PARAM_DEL, false);
        err = devlink->ops->reload_down(devlink, !!dest_net, action, limit, extack);
        if (err)
                return err;

@@ -3971,7 +3971,7 @@ static int devlink_reload(struct devlink *devlink, struct net *dest_net,
                return err;
 
        devlink_params_notify(devlink, dest_net, curr_net,
-                             DEVLINK_CMD_PARAM_NEW);
+                             DEVLINK_CMD_PARAM_NEW, true);
        WARN_ON(!(*actions_performed & BIT(action)));
        /* Catch driver on updating the remote action within devlink reload */
        WARN_ON(memcmp(remote_reload_stats, devlink->stats.remote_reload_stats,

quoted

  3864 
  3865         list_for_each_entry(param_item, &devlink->param_list, list)
  3866                 devlink_param_notify(devlink, 0, param_item, cmd);
  3867 
  3868         if (cmd == DEVLINK_CMD_PARAM_DEL)
  3869                 devlink_notify(devlink, DEVLINK_CMD_DEL);
  3870 }


So as you can see in line 3866, we anyway will need to provide "cmd", so
do you suggest to add extra two bool variables to the function signature
to avoid "cmd == DEVLINK_CMD_PARAM_NEW" and "cmd == DEVLINK_CMD_PARAM_DEL" ifs?

Thanks