Re: [PATCH v3 1/2] net: core: Notify on changes to dev->promiscuity.

[Jiri Pirko <jiri@resnulli.us>]

Thu, Aug 29, 2019 at 11:22:28AM CEST, horatiu.vultur@microchip.com wrote:
>Add the SWITCHDEV_ATTR_ID_PORT_PROMISCUITY switchdev notification type,
>used to indicate whenever the dev promiscuity counter is changed.
>
>The notification doesn't use any switchdev_attr attribute because in the
>notifier callbacks is it possible to get the dev and read directly
>the promiscuity value.
>
>Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
>---
> include/net/switchdev.h | 1 +
> net/core/dev.c          | 9 +++++++++
> 2 files changed, 10 insertions(+)
>
>diff --git a/include/net/switchdev.h b/include/net/switchdev.h
>index aee86a1..14b1617 100644
>--- a/include/net/switchdev.h
>+++ b/include/net/switchdev.h
>@@ -40,6 +40,7 @@ enum switchdev_attr_id {
> 	SWITCHDEV_ATTR_ID_BRIDGE_VLAN_FILTERING,
> 	SWITCHDEV_ATTR_ID_BRIDGE_MC_DISABLED,
> 	SWITCHDEV_ATTR_ID_BRIDGE_MROUTER,
>+	SWITCHDEV_ATTR_ID_PORT_PROMISCUITY,
> };
> 
> struct switchdev_attr {
>diff --git a/net/core/dev.c b/net/core/dev.c
>index 49589ed..40c74f2 100644
>--- a/net/core/dev.c
>+++ b/net/core/dev.c
>@@ -142,6 +142,7 @@
> #include <linux/net_namespace.h>
> #include <linux/indirect_call_wrapper.h>
> #include <net/devlink.h>
>+#include <net/switchdev.h>
> 
> #include "net-sysfs.h"
> 
>@@ -7377,6 +7378,11 @@ static void dev_change_rx_flags(struct net_device *dev, int flags)
> static int __dev_set_promiscuity(struct net_device *dev, int inc, bool notify)
> {
> 	unsigned int old_flags = dev->flags;
>+	struct switchdev_attr attr = {
>+		.orig_dev = dev,
>+		.id = SWITCHDEV_ATTR_ID_PORT_PROMISCUITY,
>+		.flags = SWITCHDEV_F_DEFER,

NACK

This is invalid usecase for switchdev infra. Switchdev is there for
bridge offload purposes only.

For promiscuity changes, the infrastructure is already present in the
code. See __dev_notify_flags(). it calls:
call_netdevice_notifiers_info(NETDEV_CHANGE, &change_info.info)
and you can actually see the changed flag in ".flags_changed".

You just have to register netdev notifier block in your driver. Grep
for: register_netdevice_notifier


>+	};
> 	kuid_t uid;
> 	kgid_t gid;
> 
>@@ -7419,6 +7425,9 @@ static int __dev_set_promiscuity(struct net_device *dev, int inc, bool notify)
> 	}
> 	if (notify)
> 		__dev_notify_flags(dev, old_flags, IFF_PROMISC);
>+
>+	switchdev_port_attr_set(dev, &attr);
>+
> 	return 0;
> }
> 
>-- 
>2.7.4
>