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

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Message-ID: <YQKSmwzppN4KNQiX@unreal>
Date:   Thu, 29 Jul 2021 14:35:55 +0300
From:   Leon Romanovsky <leon@...nel.org>
To:     Jiri Pirko <jiri@...nulli.us>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, Jiri Pirko <jiri@...dia.com>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        Parav Pandit <parav@...dia.com>
Subject: Re: [PATCH net-next 1/2] devlink: Break parameter notification
 sequence to be before/after unload/load driver

On Thu, Jul 29, 2021 at 01:22:58PM +0200, Jiri Pirko wrote:
> Thu, Jul 29, 2021 at 10:15:25AM CEST, leon@...nel.org wrote:
> >From: Leon Romanovsky <leonro@...dia.com>

<...>

> >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?

> 
> 
> >+				  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);
   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