Date:   Wed, 18 Apr 2018 22:32:06 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     "Michael S. Tsirkin" <mst@...hat.com>
Cc:     "Samudrala, Sridhar" <sridhar.samudrala@...el.com>,
        stephen@...workplumber.org, davem@...emloft.net,
        netdev@...r.kernel.org, virtualization@...ts.linux-foundation.org,
        virtio-dev@...ts.oasis-open.org, jesse.brandeburg@...el.com,
        alexander.h.duyck@...el.com, kubakici@...pl, jasowang@...hat.com,
        loseweigh@...il.com
Subject: Re: [RFC PATCH net-next v6 2/4] net: Introduce generic bypass module

Wed, Apr 18, 2018 at 09:46:04PM CEST, mst@...hat.com wrote:
>On Wed, Apr 18, 2018 at 09:13:15PM +0200, Jiri Pirko wrote:
>> Wed, Apr 18, 2018 at 08:43:15PM CEST, sridhar.samudrala@...el.com wrote:
>> >On 4/18/2018 2:25 AM, Jiri Pirko wrote:
>> >> Wed, Apr 11, 2018 at 09:13:52PM CEST, sridhar.samudrala@...el.com wrote:
>> >> > On 4/11/2018 8:51 AM, Jiri Pirko wrote:
>> >> > > Tue, Apr 10, 2018 at 08:59:48PM CEST, sridhar.samudrala@...el.com wrote:
>> >> > > > This provides a generic interface for paravirtual drivers to listen
>> >> > > > for netdev register/unregister/link change events from pci ethernet
>> >> > > > devices with the same MAC and takeover their datapath. The notifier and
>> >> > > > event handling code is based on the existing netvsc implementation.
>> >> > > > 
>> >> > > > It exposes 2 sets of interfaces to the paravirtual drivers.
>> >> > > > 1. existing netvsc driver that uses 2 netdev model. In this model, no
>> >> > > > master netdev is created. The paravirtual driver registers each bypass
>> >> > > > instance along with a set of ops to manage the slave events.
>> >> > > >       bypass_master_register()
>> >> > > >       bypass_master_unregister()
>> >> > > > 2. new virtio_net based solution that uses 3 netdev model. In this model,
>> >> > > > the bypass module provides interfaces to create/destroy additional master
>> >> > > > netdev and all the slave events are managed internally.
>> >> > > >        bypass_master_create()
>> >> > > >        bypass_master_destroy()
>> >> > > > 
>> >> > > > Signed-off-by: Sridhar Samudrala <sridhar.samudrala@...el.com>
>> >> > > > ---
>> >> > > > include/linux/netdevice.h |  14 +
>> >> > > > include/net/bypass.h      |  96 ++++++
>> >> > > > net/Kconfig               |  18 +
>> >> > > > net/core/Makefile         |   1 +
>> >> > > > net/core/bypass.c         | 844 ++++++++++++++++++++++++++++++++++++++++++++++
>> >> > > > 5 files changed, 973 insertions(+)
>> >> > > > create mode 100644 include/net/bypass.h
>> >> > > > create mode 100644 net/core/bypass.c
>> >> > > > 
>> >> > > > diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
>> >> > > > index cf44503ea81a..587293728f70 100644
>> >> > > > --- a/include/linux/netdevice.h
>> >> > > > +++ b/include/linux/netdevice.h
>> >> > > > @@ -1430,6 +1430,8 @@ enum netdev_priv_flags {
>> >> > > > 	IFF_PHONY_HEADROOM		= 1<<24,
>> >> > > > 	IFF_MACSEC			= 1<<25,
>> >> > > > 	IFF_NO_RX_HANDLER		= 1<<26,
>> >> > > > +	IFF_BYPASS			= 1 << 27,
>> >> > > > +	IFF_BYPASS_SLAVE		= 1 << 28,
>> >> > > I wonder, why you don't follow the existing coding style... Also, please
>> >> > > add these to into the comment above.
>> >> > To avoid checkpatch warnings. If it is OK to ignore these warnings, I can switch back
>> >> > to the existing coding style to be consistent.
>> >> Please do.
>> >> 
>> >> 
>> >> > > 
>> >> > > > };
>> >> > > > 
>> >> > > > #define IFF_802_1Q_VLAN			IFF_802_1Q_VLAN
>> >> > > > @@ -1458,6 +1460,8 @@ enum netdev_priv_flags {
>> >> > > > #define IFF_RXFH_CONFIGURED		IFF_RXFH_CONFIGURED
>> >> > > > #define IFF_MACSEC			IFF_MACSEC
>> >> > > > #define IFF_NO_RX_HANDLER		IFF_NO_RX_HANDLER
>> >> > > > +#define IFF_BYPASS			IFF_BYPASS
>> >> > > > +#define IFF_BYPASS_SLAVE		IFF_BYPASS_SLAVE
>> >> > > > 
>> >> > > > /**
>> >> > > >    *	struct net_device - The DEVICE structure.
>> >> > > > @@ -4308,6 +4312,16 @@ static inline bool netif_is_rxfh_configured(const struct net_device *dev)
>> >> > > > 	return dev->priv_flags & IFF_RXFH_CONFIGURED;
>> >> > > > }
>> >> > > > 
>> >> > > > +static inline bool netif_is_bypass_master(const struct net_device *dev)
>> >> > > > +{
>> >> > > > +	return dev->priv_flags & IFF_BYPASS;
>> >> > > > +}
>> >> > > > +
>> >> > > > +static inline bool netif_is_bypass_slave(const struct net_device *dev)
>> >> > > > +{
>> >> > > > +	return dev->priv_flags & IFF_BYPASS_SLAVE;
>> >> > > > +}
>> >> > > > +
>> >> > > > /* This device needs to keep skb dst for qdisc enqueue or ndo_start_xmit() */
>> >> > > > static inline void netif_keep_dst(struct net_device *dev)
>> >> > > > {
>> >> > > > diff --git a/include/net/bypass.h b/include/net/bypass.h
>> >> > > > new file mode 100644
>> >> > > > index 000000000000..86b02cb894cf
>> >> > > > --- /dev/null
>> >> > > > +++ b/include/net/bypass.h
>> >> > > > @@ -0,0 +1,96 @@
>> >> > > > +// SPDX-License-Identifier: GPL-2.0
>> >> > > > +/* Copyright (c) 2018, Intel Corporation. */
>> >> > > > +
>> >> > > > +#ifndef _NET_BYPASS_H
>> >> > > > +#define _NET_BYPASS_H
>> >> > > > +
>> >> > > > +#include <linux/netdevice.h>
>> >> > > > +
>> >> > > > +struct bypass_ops {
>> >> > > > +	int (*slave_pre_register)(struct net_device *slave_netdev,
>> >> > > > +				  struct net_device *bypass_netdev);
>> >> > > > +	int (*slave_join)(struct net_device *slave_netdev,
>> >> > > > +			  struct net_device *bypass_netdev);
>> >> > > > +	int (*slave_pre_unregister)(struct net_device *slave_netdev,
>> >> > > > +				    struct net_device *bypass_netdev);
>> >> > > > +	int (*slave_release)(struct net_device *slave_netdev,
>> >> > > > +			     struct net_device *bypass_netdev);
>> >> > > > +	int (*slave_link_change)(struct net_device *slave_netdev,
>> >> > > > +				 struct net_device *bypass_netdev);
>> >> > > > +	rx_handler_result_t (*handle_frame)(struct sk_buff **pskb);
>> >> > > > +};
>> >> > > > +
>> >> > > > +struct bypass_master {
>> >> > > > +	struct list_head list;
>> >> > > > +	struct net_device __rcu *bypass_netdev;
>> >> > > > +	struct bypass_ops __rcu *ops;
>> >> > > > +};
>> >> > > > +
>> >> > > > +/* bypass state */
>> >> > > > +struct bypass_info {
>> >> > > > +	/* passthru netdev with same MAC */
>> >> > > > +	struct net_device __rcu *active_netdev;
>> >> > > You still use "active"/"backup" names which is highly misleading as
>> >> > > it has completely different meaning that in bond for example.
>> >> > > I noted that in my previous review already. Please change it.
>> >> > I guess the issue is with only the 'active'  name. 'backup' should be fine as it also
>> >> > matches with the BACKUP feature bit we are adding to virtio_net.
>> >> I think that "backup" is also misleading. Both "active" and "backup"
>> >> mean a *state* of slaves. This should be named differently.
>> >> 
>> >> 
>> >> 
>> >> > With regards to alternate names for 'active', you suggested 'stolen', but i
>> >> > am not too happy with it.
>> >> > netvsc uses vf_netdev, are you OK with this? Or another option is 'passthru'
>> >> No. The netdev could be any netdevice. It does not have to be a "VF".
>> >> I think "stolen" is quite appropriate since it describes the modus
>> >> operandi. The bypass master steals some netdevice according to some
>> >> match.
>> >> 
>> >> But I don't insist on "stolen". Just sounds right.
>> >
>> >We are adding VIRTIO_NET_F_BACKUP as a new feature bit to enable this feature, So i think
>> >'backup' name is consistent.
>> 
>> It perhaps makes sense from the view of virtio device. However, as I
>> described couple of times, for master/slave device the name "backup" is
>> highly misleading.
>
>virtio is the backup. You are supposed to use another
>(typically passthrough) device, if that fails use virtio.
>It does seem appropriate to me. If you like, we can
>change that to "standby".  Active I don't like either. "main"?

Sounds much better, yes.


>
>In fact would failover be better than bypass?

Also, much better.


>
>
>> 
>> >
>> >The intent is to restrict the 'active' netdev to be a VF. If there is a way to check that
>> >a PCI device is a VF in the guest kernel, we could restrict 'active' netdev to be a VF.
>> >
>> >Will look for any suggestions in the next day or two. If i don't get any, i will go
>> >with 'stolen'
>> >
>> ><snip>
>> >
>> >
>> >> +
>> >> +static struct net_device *bypass_master_get_bymac(u8 *mac,
>> >> +						  struct bypass_ops **ops)
>> >> +{
>> >> +	struct bypass_master *bypass_master;
>> >> +	struct net_device *bypass_netdev;
>> >> +
>> >> +	spin_lock(&bypass_lock);
>> >> +	list_for_each_entry(bypass_master, &bypass_master_list, list) {
>> >> > > As I wrote the last time, you don't need this list, spinlock.
>> >> > > You can do just something like:
>> >> > >           for_each_net(net) {
>> >> > >                   for_each_netdev(net, dev) {
>> >> > > 			if (netif_is_bypass_master(dev)) {
>> >> > This function returns the upper netdev as well as the ops associated
>> >> > with that netdev.
>> >> > bypass_master_list is a list of 'struct bypass_master' that associates
>> >> Well, can't you have it in netdev priv?
>> >
>> >We cannot do this for 2-netdev model as there is no bypass_netdev created.
>> 
>> Howcome? You have no master? I don't understand..
>> 
>> 
>> 
>> >
>> >> 
>> >> 
>> >> > 'bypass_netdev' with 'bypass_ops' and gets added via bypass_master_register().
>> >> > We need 'ops' only to support the 2 netdev model of netvsc. ops will be
>> >> > NULL for 3-netdev model.
>> >> I see :(
>> >> 
>> >> 
>> >> > 
>> >> > > 
>> >> > > 
>> >> > > 
>> >> > > > +		bypass_netdev = rcu_dereference(bypass_master->bypass_netdev);
>> >> > > > +		if (ether_addr_equal(bypass_netdev->perm_addr, mac)) {
>> >> > > > +			*ops = rcu_dereference(bypass_master->ops);
>> >> > > I don't see how rcu_dereference is ok here.
>> >> > > 1) I don't see rcu_read_lock taken
>> >> > > 2) Looks like bypass_master->ops has the same value across the whole
>> >> > >      existence.
>> >> > We hold rtnl_lock(), i think i need to change this to rtnl_dereference.
>> >> > Yes. ops doesn't change.
>> >> If it does not change, you can just access it directly.
>> >> 
>> >> 
>> >> > > 
>> >> > > > +			spin_unlock(&bypass_lock);
>> >> > > > +			return bypass_netdev;
>> >> > > > +		}
>> >> > > > +	}
>> >> > > > +	spin_unlock(&bypass_lock);
>> >> > > > +	return NULL;
>> >> > > > +}
>> >> > > > +
>> >> > > > +static int bypass_slave_register(struct net_device *slave_netdev)
>> >> > > > +{
>> >> > > > +	struct net_device *bypass_netdev;
>> >> > > > +	struct bypass_ops *bypass_ops;
>> >> > > > +	int ret, orig_mtu;
>> >> > > > +
>> >> > > > +	ASSERT_RTNL();
>> >> > > > +
>> >> > > > +	bypass_netdev = bypass_master_get_bymac(slave_netdev->perm_addr,
>> >> > > > +						&bypass_ops);
>> >> > > For master, could you use word "master" in the variables so it is clear?
>> >> > > Also, "dev" is fine instead of "netdev".
>> >> > > Something like "bpmaster_dev"
>> >> > bypass_master is of  type struct bypass_master,  bypass_netdev is of type struct net_device.
>> >> I was trying to point out, that "bypass_netdev" represents a "master"
>> >> netdev, yet it does not say master. That is why I suggested
>> >> "bpmaster_dev"
>> >> 
>> >> 
>> >> > I can change all _netdev suffixes to _dev to make the names shorter.
>> >> ok.
>> >> 
>> >> 
>> >> > 
>> >> > > 
>> >> > > > +	if (!bypass_netdev)
>> >> > > > +		goto done;
>> >> > > > +
>> >> > > > +	ret = bypass_slave_pre_register(slave_netdev, bypass_netdev,
>> >> > > > +					bypass_ops);
>> >> > > > +	if (ret != 0)
>> >> > > 	Just "if (ret)" will do. You have this on more places.
>> >> > OK.
>> >> > 
>> >> > 
>> >> > > 
>> >> > > > +		goto done;
>> >> > > > +
>> >> > > > +	ret = netdev_rx_handler_register(slave_netdev,
>> >> > > > +					 bypass_ops ? bypass_ops->handle_frame :
>> >> > > > +					 bypass_handle_frame, bypass_netdev);
>> >> > > > +	if (ret != 0) {
>> >> > > > +		netdev_err(slave_netdev, "can not register bypass rx handler (err = %d)\n",
>> >> > > > +			   ret);
>> >> > > > +		goto done;
>> >> > > > +	}
>> >> > > > +
>> >> > > > +	ret = netdev_upper_dev_link(slave_netdev, bypass_netdev, NULL);
>> >> > > > +	if (ret != 0) {
>> >> > > > +		netdev_err(slave_netdev, "can not set master device %s (err = %d)\n",
>> >> > > > +			   bypass_netdev->name, ret);
>> >> > > > +		goto upper_link_failed;
>> >> > > > +	}
>> >> > > > +
>> >> > > > +	slave_netdev->priv_flags |= IFF_BYPASS_SLAVE;
>> >> > > > +
>> >> > > > +	if (netif_running(bypass_netdev)) {
>> >> > > > +		ret = dev_open(slave_netdev);
>> >> > > > +		if (ret && (ret != -EBUSY)) {
>> >> > > > +			netdev_err(bypass_netdev, "Opening slave %s failed ret:%d\n",
>> >> > > > +				   slave_netdev->name, ret);
>> >> > > > +			goto err_interface_up;
>> >> > > > +		}
>> >> > > > +	}
>> >> > > > +
>> >> > > > +	/* Align MTU of slave with master */
>> >> > > > +	orig_mtu = slave_netdev->mtu;
>> >> > > > +	ret = dev_set_mtu(slave_netdev, bypass_netdev->mtu);
>> >> > > > +	if (ret != 0) {
>> >> > > > +		netdev_err(bypass_netdev, "unable to change mtu of %s to %u register failed\n",
>> >> > > > +			   slave_netdev->name, bypass_netdev->mtu);
>> >> > > > +		goto err_set_mtu;
>> >> > > > +	}
>> >> > > > +
>> >> > > > +	ret = bypass_slave_join(slave_netdev, bypass_netdev, bypass_ops);
>> >> > > > +	if (ret != 0)
>> >> > > > +		goto err_join;
>> >> > > > +
>> >> > > > +	call_netdevice_notifiers(NETDEV_JOIN, slave_netdev);
>> >> > > > +
>> >> > > > +	netdev_info(bypass_netdev, "bypass slave:%s registered\n",
>> >> > > > +		    slave_netdev->name);
>> >> > > > +
>> >> > > > +	goto done;
>> >> > > > +
>> >> > > > +err_join:
>> >> > > > +	dev_set_mtu(slave_netdev, orig_mtu);
>> >> > > > +err_set_mtu:
>> >> > > > +	dev_close(slave_netdev);
>> >> > > > +err_interface_up:
>> >> > > > +	netdev_upper_dev_unlink(slave_netdev, bypass_netdev);
>> >> > > > +	slave_netdev->priv_flags &= ~IFF_BYPASS_SLAVE;
>> >> > > > +upper_link_failed:
>> >> > > > +	netdev_rx_handler_unregister(slave_netdev);
>> >> > > > +done:
>> >> > > > +	return NOTIFY_DONE;
>> >> > > > +}
>> >> > > > +
>> >> > > > +static int bypass_slave_pre_unregister(struct net_device *slave_netdev,
>> >> > > > +				       struct net_device *bypass_netdev,
>> >> > > > +				       struct bypass_ops *bypass_ops)
>> >> > > > +{
>> >> > > > +	struct net_device *backup_netdev, *active_netdev;
>> >> > > > +	struct bypass_info *bi;
>> >> > > > +
>> >> > > > +	if (bypass_ops) {
>> >> > > > +		if (!bypass_ops->slave_pre_unregister)
>> >> > > > +			return -EINVAL;
>> >> > > > +
>> >> > > > +		return bypass_ops->slave_pre_unregister(slave_netdev,
>> >> > > > +							bypass_netdev);
>> >> > > > +	}
>> >> > > > +
>> >> > > > +	bi = netdev_priv(bypass_netdev);
>> >> > > > +	active_netdev = rtnl_dereference(bi->active_netdev);
>> >> > > > +	backup_netdev = rtnl_dereference(bi->backup_netdev);
>> >> > > > +
>> >> > > > +	if (slave_netdev != active_netdev && slave_netdev != backup_netdev)
>> >> > > > +		return -EINVAL;
>> >> > > > +
>> >> > > > +	return 0;
>> >> > > > +}
>> >> > > > +
>> >> > > > +static int bypass_slave_release(struct net_device *slave_netdev,
>> >> > > > +				struct net_device *bypass_netdev,
>> >> > > > +				struct bypass_ops *bypass_ops)
>> >> > > > +{
>> >> > > > +	struct net_device *backup_netdev, *active_netdev;
>> >> > > > +	struct bypass_info *bi;
>> >> > > > +
>> >> > > > +	if (bypass_ops) {
>> >> > > > +		if (!bypass_ops->slave_release)
>> >> > > > +			return -EINVAL;
>> >> > > I think it would be good to make the API to the driver more strict and
>> >> > > have a separate set of ops for "active" and "backup" netdevices.
>> >> > > That should stop people thinking about extending this to more slaves in
>> >> > > the future.
>> >> > We have checks in slave_pre_register() that allows only 1 'backup' and 1
>> >> > 'active' slave.
>> >> I'm very well aware of that. I just thought that explicit ops for the
>> >> two slaves would make this more clear.
>> >> 
>> >> 
>> >> > 
>> >> > > 
>> >> > > 
>> >> > > > +
>> >> > > > +		return bypass_ops->slave_release(slave_netdev, bypass_netdev);
>> >> > > > +	}
>> >> > > > +
>> >> > > > +	bi = netdev_priv(bypass_netdev);
>> >> > > > +	active_netdev = rtnl_dereference(bi->active_netdev);
>> >> > > > +	backup_netdev = rtnl_dereference(bi->backup_netdev);
>> >> > > > +
>> >> > > > +	if (slave_netdev == backup_netdev) {
>> >> > > > +		RCU_INIT_POINTER(bi->backup_netdev, NULL);
>> >> > > > +	} else {
>> >> > > > +		RCU_INIT_POINTER(bi->active_netdev, NULL);
>> >> > > > +		if (backup_netdev) {
>> >> > > > +			bypass_netdev->min_mtu = backup_netdev->min_mtu;
>> >> > > > +			bypass_netdev->max_mtu = backup_netdev->max_mtu;
>> >> > > > +		}
>> >> > > > +	}
>> >> > > > +
>> >> > > > +	dev_put(slave_netdev);
>> >> > > > +
>> >> > > > +	netdev_info(bypass_netdev, "bypass slave:%s released\n",
>> >> > > > +		    slave_netdev->name);
>> >> > > > +
>> >> > > > +	return 0;
>> >> > > > +}
>> >> > > > +
>> >> > > > +int bypass_slave_unregister(struct net_device *slave_netdev)
>> >> > > > +{
>> >> > > > +	struct net_device *bypass_netdev;
>> >> > > > +	struct bypass_ops *bypass_ops;
>> >> > > > +	int ret;
>> >> > > > +
>> >> > > > +	if (!netif_is_bypass_slave(slave_netdev))
>> >> > > > +		goto done;
>> >> > > > +
>> >> > > > +	ASSERT_RTNL();
>> >> > > > +
>> >> > > > +	bypass_netdev = bypass_master_get_bymac(slave_netdev->perm_addr,
>> >> > > > +						&bypass_ops);
>> >> > > > +	if (!bypass_netdev)
>> >> > > > +		goto done;
>> >> > > > +
>> >> > > > +	ret = bypass_slave_pre_unregister(slave_netdev, bypass_netdev,
>> >> > > > +					  bypass_ops);
>> >> > > > +	if (ret != 0)
>> >> > > > +		goto done;
>> >> > > > +
>> >> > > > +	netdev_rx_handler_unregister(slave_netdev);
>> >> > > > +	netdev_upper_dev_unlink(slave_netdev, bypass_netdev);
>> >> > > > +	slave_netdev->priv_flags &= ~IFF_BYPASS_SLAVE;
>> >> > > > +
>> >> > > > +	bypass_slave_release(slave_netdev, bypass_netdev, bypass_ops);
>> >> > > > +
>> >> > > > +	netdev_info(bypass_netdev, "bypass slave:%s unregistered\n",
>> >> > > > +		    slave_netdev->name);
>> >> > > > +
>> >> > > > +done:
>> >> > > > +	return NOTIFY_DONE;
>> >> > > > +}
>> >> > > > +EXPORT_SYMBOL_GPL(bypass_slave_unregister);
>> >> > > > +
>> >> > > > +static bool bypass_xmit_ready(struct net_device *dev)
>> >> > > > +{
>> >> > > > +	return netif_running(dev) && netif_carrier_ok(dev);
>> >> > > > +}
>> >> > > > +
>> >> > > > +static int bypass_slave_link_change(struct net_device *slave_netdev)
>> >> > > > +{
>> >> > > > +	struct net_device *bypass_netdev, *active_netdev, *backup_netdev;
>> >> > > > +	struct bypass_ops *bypass_ops;
>> >> > > > +	struct bypass_info *bi;
>> >> > > > +
>> >> > > > +	if (!netif_is_bypass_slave(slave_netdev))
>> >> > > > +		goto done;
>> >> > > > +
>> >> > > > +	ASSERT_RTNL();
>> >> > > > +
>> >> > > > +	bypass_netdev = bypass_master_get_bymac(slave_netdev->perm_addr,
>> >> > > > +						&bypass_ops);
>> >> > > > +	if (!bypass_netdev)
>> >> > > > +		goto done;
>> >> > > > +
>> >> > > > +	if (bypass_ops) {
>> >> > > > +		if (!bypass_ops->slave_link_change)
>> >> > > > +			goto done;
>> >> > > > +
>> >> > > > +		return bypass_ops->slave_link_change(slave_netdev,
>> >> > > > +						     bypass_netdev);
>> >> > > > +	}
>> >> > > > +
>> >> > > > +	if (!netif_running(bypass_netdev))
>> >> > > > +		return 0;
>> >> > > > +
>> >> > > > +	bi = netdev_priv(bypass_netdev);
>> >> > > > +
>> >> > > > +	active_netdev = rtnl_dereference(bi->active_netdev);
>> >> > > > +	backup_netdev = rtnl_dereference(bi->backup_netdev);
>> >> > > > +
>> >> > > > +	if (slave_netdev != active_netdev && slave_netdev != backup_netdev)
>> >> > > > +		goto done;
>> >> > > You don't need this check. "if (!netif_is_bypass_slave(slave_netdev))"
>> >> > > above is enough.
>> >> > I think we need this check to not allow events from a slave that is not
>> >> > attached to this master but has the same MAC.
>> >> Why do we need such events? Seems wrong to me.
>> >
>> >We want to avoid events from a netdev that is mis-configured with the same MAC as
>> >a bypass setup.
>> >
>> >>   Consider:
>> >> 
>> >> bp1      bp2
>> >> a1 b1    a2 b2
>> >> 
>> >> 
>> >> a1 and a2 have the same mac and bp1 and bp2 have the same mac.
>> >
>> >We should not have 2 bypass configs with the same MAC.
>> >I need to add a check in the bypass_master_register() to prevent this.
>> 
>> Mac can change, you would have to check in change as well. Feels odd
>> thought. 
>> 
>> 
>> >
>> >The above check is to avoid cases where we have
>> >bp1(a1, b1) with mac1
>> >and a2 is mis-configured with mac1, we want to avoid using a2 link events to update bp1.
>> >
>> >> Now bypass_master_get_bymac() will return always bp1 or bp2 - depending on
>> >> the order of creation.
>> >> Let's say it will return bp1. Then when we have event for a2, the
>> >> bypass_ops->slave_link_change is called with (a2, bp1). That is wrong.
>> >> 
>> >> 
>> >> You cannot use bypass_master_get_bymac() here.
>> >> 
>> >> 
>> >> 
>> >> > > 
>> >> > > > +
>> >> > > > +	if ((active_netdev && bypass_xmit_ready(active_netdev)) ||
>> >> > > > +	    (backup_netdev && bypass_xmit_ready(backup_netdev))) {
>> >> > > > +		netif_carrier_on(bypass_netdev);
>> >> > > > +		netif_tx_wake_all_queues(bypass_netdev);
>> >> > > > +	} else {
>> >> > > > +		netif_carrier_off(bypass_netdev);
>> >> > > > +		netif_tx_stop_all_queues(bypass_netdev);
>> >> > > > +	}
>> >> > > > +
>> >> > > > +done:
>> >> > > > +	return NOTIFY_DONE;
>> >> > > > +}
>> >> > > > +
>> >> > > > +static bool bypass_validate_event_dev(struct net_device *dev)
>> >> > > > +{
>> >> > > > +	/* Skip parent events */
>> >> > > > +	if (netif_is_bypass_master(dev))
>> >> > > > +		return false;
>> >> > > > +
>> >> > > > +	/* Avoid non-Ethernet type devices */
>> >> > > > +	if (dev->type != ARPHRD_ETHER)
>> >> > > > +		return false;
>> >> > > > +
>> >> > > > +	/* Avoid Vlan dev with same MAC registering as VF */
>> >> > > > +	if (is_vlan_dev(dev))
>> >> > > > +		return false;
>> >> > > > +
>> >> > > > +	/* Avoid Bonding master dev with same MAC registering as slave dev */
>> >> > > > +	if ((dev->priv_flags & IFF_BONDING) && (dev->flags & IFF_MASTER))
>> >> > > Yeah, this is certainly incorrect. One thing is, you should be using the
>> >> > > helpers netif_is_bond_master().
>> >> > > But what about the rest? macsec, macvlan, team, bridge, ovs and others?
>> >> > > 
>> >> > > You need to do it not by blacklisting, but with whitelisting. You need
>> >> > > to whitelist VF devices. My port flavours patchset might help with this.
>> >> > May be i can use netdev_has_lower_dev() helper to make sure that the slave
>> >> I don't see such function in the code.
>> >
>> >It is netdev_has_any_lower_dev(). I need to export it.
>> 
>> Come on, you cannot use that. That would allow bonding without slaves,
>> but the slaves could be added later on.
>> 
>> What exactly you are trying to achieve by this?
>> 
>> 
>> >
>> >> 
>> >> 
>> >> > device is not an upper dev.
>> >> > Can you point to your port flavours patchset? Is it upstream?
>> >> I sent rfc couple of weeks ago:
>> >> [patch net-next RFC 00/12] devlink: introduce port flavours and common phys_port_name generation
>> >
>> >
>> >

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