netdev - Re: [PATCH net-next v3 2/6] devlink: create a special NDO for getting the devlink instance

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Date:   Sun, 24 Feb 2019 11:51:57 +0100
From:   Jiri Pirko <jiri@...nulli.us>
To:     Jakub Kicinski <jakub.kicinski@...ronome.com>
Cc:     davem@...emloft.net, mkubecek@...e.cz, andrew@...n.ch,
        f.fainelli@...il.com, netdev@...r.kernel.org,
        oss-drivers@...ronome.com
Subject: Re: [PATCH net-next v3 2/6] devlink: create a special NDO for
 getting the devlink instance

Fri, Feb 22, 2019 at 11:07:53PM CET, jakub.kicinski@...ronome.com wrote:
>Instead of iterating over all devlink ports add a NDO which
>will return the devlink instance from the driver.
>
>v2: add the netdev_to_devlink() helper (Michal)
>v3: check that devlink has ops (Florian)
>
>Suggested-by: Jiri Pirko <jiri@...nulli.us>
>Signed-off-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
>Reviewed-by: Florian Fainelli <f.fainelli@...il.com>

[...]


> void devlink_compat_running_version(struct net_device *dev,
> 				    char *buf, size_t len)
> {
>-	struct devlink_port *devlink_port;
> 	struct devlink *devlink;
> 
>-	mutex_lock(&devlink_mutex);
>-	list_for_each_entry(devlink, &devlink_list, list) {
>-		mutex_lock(&devlink->lock);
>-		list_for_each_entry(devlink_port, &devlink->port_list, list) {
>-			if (devlink_port->type == DEVLINK_PORT_TYPE_ETH &&
>-			    devlink_port->type_dev == dev) {
>-				__devlink_compat_running_version(devlink,
>-								 buf, len);
>-				mutex_unlock(&devlink->lock);
>-				goto out;
>-			}
>-		}
>-		mutex_unlock(&devlink->lock);
>-	}
>-out:
>-	mutex_unlock(&devlink_mutex);
>+	devlink = netdev_to_devlink(dev);

What prevents devlink from being unregistered now from another thread?
I think you should hold &devlink_mutex here to prevent it.



>+	if (!devlink || !devlink->ops || !devlink->ops->info_get)
>+		return;
>+
>+	mutex_lock(&devlink->lock);
>+	__devlink_compat_running_version(devlink, buf, len);
>+	mutex_unlock(&devlink->lock);
> }
> 
> int devlink_compat_flash_update(struct net_device *dev, const char *file_name)
> {
>-	struct devlink_port *devlink_port;
> 	struct devlink *devlink;
>+	int ret;
> 
>-	mutex_lock(&devlink_mutex);
>-	list_for_each_entry(devlink, &devlink_list, list) {
>-		mutex_lock(&devlink->lock);
>-		list_for_each_entry(devlink_port, &devlink->port_list, list) {
>-			int ret = -EOPNOTSUPP;
>-
>-			if (devlink_port->type != DEVLINK_PORT_TYPE_ETH ||
>-			    devlink_port->type_dev != dev)
>-				continue;
>-
>-			mutex_unlock(&devlink_mutex);
>-			if (devlink->ops->flash_update)
>-				ret = devlink->ops->flash_update(devlink,
>-								 file_name,
>-								 NULL, NULL);
>-			mutex_unlock(&devlink->lock);
>-			return ret;
>-		}
>-		mutex_unlock(&devlink->lock);
>-	}
>-	mutex_unlock(&devlink_mutex);
>+	devlink = netdev_to_devlink(dev);

Same here.


>+	if (!devlink || !devlink->ops || !devlink->ops->flash_update)
>+		return -EOPNOTSUPP;
> 
>-	return -EOPNOTSUPP;
>+	mutex_lock(&devlink->lock);
>+	ret = devlink->ops->flash_update(devlink, file_name, NULL, NULL);
>+	mutex_unlock(&devlink->lock);
>+	return ret;
> }
> 
> static int __init devlink_init(void)
>-- 
>2.19.2
>