netdev - Re: [RFC next-next v2 1/5] net: marvell: prestera: Add driver for Prestera family ASIC devices

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Date:   Tue, 12 May 2020 17:21:36 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     Vadym Kochan <vadym.kochan@...ision.eu>
Cc:     netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
        Oleksandr Mazur <oleksandr.mazur@...ision.eu>,
        Serhiy Boiko <serhiy.boiko@...ision.eu>,
        Serhiy Pshyk <serhiy.pshyk@...ision.eu>,
        Volodymyr Mytnyk <volodymyr.mytnyk@...ision.eu>,
        Taras Chornyi <taras.chornyi@...ision.eu>,
        Andrii Savka <andrii.savka@...ision.eu>,
        Jiri Pirko <jiri@...lanox.com>,
        Ido Schimmel <idosch@...lanox.com>,
        Andrew Lunn <andrew@...n.ch>,
        Chris Packham <Chris.Packham@...iedtelesis.co.nz>
Subject: Re: [RFC next-next v2 1/5] net: marvell: prestera: Add driver for
 Prestera family ASIC devices

Tue, May 12, 2020 at 05:07:14PM CEST, vadym.kochan@...ision.eu wrote:
>On Tue, May 12, 2020 at 05:03:06PM +0200, Jiri Pirko wrote:
>> Tue, May 12, 2020 at 04:53:52PM CEST, vadym.kochan@...ision.eu wrote:
>> >On Mon, May 11, 2020 at 12:32:22PM +0200, Jiri Pirko wrote:
>> >
>> >[...]
>> >
>> >> 
>> >> This is RCU list. Treat it accordingly.
>> >> 
>> >> 
>> >> >+	spin_unlock(&sw->ports_lock);
>> >> 
>> >> I don't follow, why do you need to protect the list by spinlock here?
>> >> More to that, why do you need the port_list reader-writer
>> >> protected (by rcu)? Is is possible that you add/remove port in the same
>> >> time packets are flying in?
>> >> 
>> >> If yes, you need to ensure the structs are in the memory (free_rcu,
>> >> synchronize_rcu). But I believe that you should disable that from
>> >> happening in HW.
>> >> 
>> >> 
>> >> >+
>> >
>> >[...]
>> >
>> >> >+
>> >> >+static int prestera_switch_init(struct prestera_switch *sw)
>> >> >+{
>> >> >+	int err;
>> >> >+
>> >> >+	err = prestera_hw_switch_init(sw);
>> >> >+	if (err) {
>> >> >+		dev_err(prestera_dev(sw), "Failed to init Switch device\n");
>> >> >+		return err;
>> >> >+	}
>> >> >+
>> >> >+	memcpy(sw->base_mac, base_mac_addr, sizeof(sw->base_mac));
>> >> >+	spin_lock_init(&sw->ports_lock);
>> >> >+	INIT_LIST_HEAD(&sw->port_list);
>> >> >+
>> >> >+	err = prestera_hw_switch_mac_set(sw, sw->base_mac);
>> >> >+	if (err)
>> >> >+		return err;
>> >> >+
>> >> >+	err = prestera_rxtx_switch_init(sw);
>> >> >+	if (err)
>> >> >+		return err;
>> >> >+
>> >> >+	err = prestera_event_handlers_register(sw);
>> >> >+	if (err)
>> >> >+		goto err_evt_handlers;
>> >> >+
>> >> >+	err = prestera_create_ports(sw);
>> >> >+	if (err)
>> >> >+		goto err_ports_create;
>> >> >+
>> >> >+	return 0;
>> >> >+
>> >> >+err_ports_create:
>> >> 
>> >> You are missing prestera_event_handlers_unregister(sw); call here.
>> >> 
>> >it is handled below in prestera_switch_fini().
>> 
>> Sure, but you should call it here in the error path as well. That is my
>> point.
>> 
>I understand your point - to make error path more clear, and symmetric ?

Yes.

>
>> >
>> >> 
>> >> >+err_evt_handlers:
>> >> >+	prestera_rxtx_switch_fini(sw);
>> >> >+
>> >> >+	return err;
>> >> >+}
>> >> >+
>> >> >+static void prestera_switch_fini(struct prestera_switch *sw)
>> >> >+{
>> >> >+	prestera_destroy_ports(sw);
>> >> >+	prestera_event_handlers_unregister(sw);
>> >> >+	prestera_rxtx_switch_fini(sw);
>> >> >+}
>> >> >+
>> >> >+int prestera_device_register(struct prestera_device *dev)
>> >> >+{
>> >> >+	struct prestera_switch *sw;
>> >> >+	int err;
>> >> >+
>> >> >+	sw = kzalloc(sizeof(*sw), GFP_KERNEL);
>> >> >+	if (!sw)
>> >> >+		return -ENOMEM;
>> >> >+
>> >> >+	dev->priv = sw;
>> >> >+	sw->dev = dev;
>> >> >+
>> >> >+	err = prestera_switch_init(sw);
>> >> >+	if (err) {
>> >> >+		kfree(sw);
>> >> >+		return err;
>> >> >+	}
>> >> >+
>> >> >+	registered_switch = sw;
>> >> >+	return 0;
>> >> >+}
>> >> >+EXPORT_SYMBOL(prestera_device_register);
>> >> >+
>> >> >+void prestera_device_unregister(struct prestera_device *dev)
>> >> >+{
>> >> >+	struct prestera_switch *sw = dev->priv;
>> >> >+
>> >> >+	registered_switch = NULL;
>> >> >+	prestera_switch_fini(sw);
>> >> >+	kfree(sw);
>> >> >+}
>> >> >+EXPORT_SYMBOL(prestera_device_unregister);
>> >> >+
>> >> >+static int __init prestera_module_init(void)
>> >> >+{
>> >> >+	if (!base_mac) {
>> >> >+		pr_err("[base_mac] parameter must be specified\n");
>> >> >+		return -EINVAL;
>> >> >+	}
>> >> >+	if (!mac_pton(base_mac, base_mac_addr)) {
>> >> >+		pr_err("[base_mac] parameter has invalid format\n");
>> >> >+		return -EINVAL;
>> >> >+	}
>> >> >+
>> >> >+	prestera_wq = alloc_workqueue("prestera", 0, 0);
>> >> >+	if (!prestera_wq)
>> >> >+		return -ENOMEM;
>> >> >+
>> >> >+	return 0;
>> >> >+}
>> >> >+
>> >> >+static void __exit prestera_module_exit(void)
>> >> >+{
>> >> >+	destroy_workqueue(prestera_wq);
>> >> >+}
>> >> >+
>> >> >+module_init(prestera_module_init);
>> >> >+module_exit(prestera_module_exit);
>> >> >+
>> >> >+MODULE_AUTHOR("Marvell Semi.");
>> >> >+MODULE_LICENSE("Dual BSD/GPL");
>> >> >+MODULE_DESCRIPTION("Marvell Prestera switch driver");
>> >> >+
>> >> >+module_param(base_mac, charp, 0);
>> >> 
>> >> No please.
>> >> 
>> >> 
>> >> [..]
>> >>