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linux-stable/include/linux/if_bridge.h
Vladimir Oltean 4e51bf44a0 net: bridge: move the switchdev object replay helpers to "push" mode 
Starting with commit 4f2673b3a2 ("net: bridge: add helper to replay
port and host-joined mdb entries"), DSA has introduced some bridge
helpers that replay switchdev events (FDB/MDB/VLAN additions and
deletions) that can be lost by the switchdev drivers in a variety of
circumstances:

- an IP multicast group was host-joined on the bridge itself before any
  switchdev port joined the bridge, leading to the host MDB entries
  missing in the hardware database.
- during the bridge creation process, the MAC address of the bridge was
  added to the FDB as an entry pointing towards the bridge device
  itself, but with no switchdev ports being part of the bridge yet, this
  local FDB entry would remain unknown to the switchdev hardware
  database.
- a VLAN/FDB/MDB was added to a bridge port that is a LAG interface,
  before any switchdev port joined that LAG, leading to the hardware
  database missing those entries.
- a switchdev port left a LAG that is a bridge port, while the LAG
  remained part of the bridge, and all FDB/MDB/VLAN entries remained
  installed in the hardware database of the switchdev port.

Also, since commit 0d2cfbd41c ("net: bridge: ignore switchdev events
for LAG ports which didn't request replay"), DSA introduced a method,
based on a const void *ctx, to ensure that two switchdev ports under the
same LAG that is a bridge port do not see the same MDB/VLAN entry being
replayed twice by the bridge, once for every bridge port that joins the
LAG.

With so many ordering corner cases being possible, it seems unreasonable
to expect a switchdev driver writer to get it right from the first try.
Therefore, now that DSA has experimented with the bridge replay helpers
for a little bit, we can move the code to the bridge driver where it is
more readily available to all switchdev drivers.

To convert the switchdev object replay helpers from "pull mode" (where
the driver asks for them) to a "push mode" (where the bridge offers them
automatically), the biggest problem is that the bridge needs to be aware
when a switchdev port joins and leaves, even when the switchdev is only
indirectly a bridge port (for example when the bridge port is a LAG
upper of the switchdev).

Luckily, we already have a hook for that, in the form of the newly
introduced switchdev_bridge_port_offload() and
switchdev_bridge_port_unoffload() calls. These offer a natural place for
hooking the object addition and deletion replays.

Extend the above 2 functions with:
- pointers to the switchdev atomic notifier (for FDB replays) and the
  blocking notifier (for MDB and VLAN replays).
- the "const void *ctx" argument required for drivers to be able to
  disambiguate between which port is targeted, when multiple ports are
  lowers of the same LAG that is a bridge port. Most of the drivers pass
  NULL to this argument, except the ones that support LAG offload and have
  the proper context check already in place in the switchdev blocking
  notifier handler.

Also unexport the replay helpers, since nobody except the bridge calls
them directly now.

Note that:
(a) we abuse the terminology slightly, because FDB entries are not
    "switchdev objects", but we count them as objects nonetheless.
    With no direct way to prove it, I think they are not modeled as
    switchdev objects because those can only be installed by the bridge
    to the hardware (as opposed to FDB entries which can be propagated
    in the other direction too). This is merely an abuse of terms, FDB
    entries are replayed too, despite not being objects.
(b) the bridge does not attempt to sync port attributes to newly joined
    ports, just the countable stuff (the objects). The reason for this
    is simple: no universal and symmetric way to sync and unsync them is
    known. For example, VLAN filtering: what to do on unsync, disable or
    leave it enabled? Similarly, STP state, ageing timer, etc etc. What
    a switchdev port does when it becomes standalone again is not really
    up to the bridge's competence, and the driver should deal with it.
    On the other hand, replaying deletions of switchdev objects can be
    seen a matter of cleanup and therefore be treated by the bridge,
    hence this patch.

We make the replay helpers opt-in for drivers, because they might not
bring immediate benefits for them:

- nbp_vlan_init() is called _after_ netdev_master_upper_dev_link(),
  so br_vlan_replay() should not do anything for the new drivers on
  which we call it. The existing drivers where there was even a slight
  possibility for there to exist a VLAN on a bridge port before they
  join it are already guarded against this: mlxsw and prestera deny
  joining LAG interfaces that are members of a bridge.

- br_fdb_replay() should now notify of local FDB entries, but I patched
  all drivers except DSA to ignore these new entries in commit
  2c4eca3ef7 ("net: bridge: switchdev: include local flag in FDB
  notifications"). Driver authors can lift this restriction as they
  wish, and when they do, they can also opt into the FDB replay
  functionality.

- br_mdb_replay() should fix a real issue which is described in commit
  4f2673b3a2 ("net: bridge: add helper to replay port and host-joined
  mdb entries"). However most drivers do not offload the
  SWITCHDEV_OBJ_ID_HOST_MDB to see this issue: only cpsw and am65_cpsw
  offload this switchdev object, and I don't completely understand the
  way in which they offload this switchdev object anyway. So I'll leave
  it up to these drivers' respective maintainers to opt into
  br_mdb_replay().

So most of the drivers pass NULL notifier blocks for the replay helpers,
except:
- dpaa2-switch which was already acked/regression-tested with the
  helpers enabled (and there isn't much of a downside in having them)
- ocelot which already had replay logic in "pull" mode
- DSA which already had replay logic in "pull" mode

An important observation is that the drivers which don't currently
request bridge event replays don't even have the
switchdev_bridge_port_{offload,unoffload} calls placed in proper places
right now. This was done to avoid unnecessary rework for drivers which
might never even add support for this. For driver writers who wish to
add replay support, this can be used as a tentative placement guide:
https://patchwork.kernel.org/project/netdevbpf/patch/20210720134655.892334-11-vladimir.oltean@nxp.com/

Cc: Vadym Kochan <vkochan@marvell.com>
Cc: Taras Chornyi <tchornyi@marvell.com>
Cc: Ioana Ciornei <ioana.ciornei@nxp.com>
Cc: Lars Povlsen <lars.povlsen@microchip.com>
Cc: Steen Hegelund <Steen.Hegelund@microchip.com>
Cc: UNGLinuxDriver@microchip.com
Cc: Claudiu Manoil <claudiu.manoil@nxp.com>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Acked-by: Ioana Ciornei <ioana.ciornei@nxp.com> # dpaa2-switch
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-07-22 00:26:23 -07:00

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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Linux ethernet bridge
*
* Authors:
* Lennert Buytenhek <buytenh@gnu.org>
*/
#ifndef _LINUX_IF_BRIDGE_H
#define _LINUX_IF_BRIDGE_H
#include <linux/netdevice.h>
#include <uapi/linux/if_bridge.h>
#include <linux/bitops.h>
struct br_ip {
union {
__be32 ip4;
#if IS_ENABLED(CONFIG_IPV6)
struct in6_addr ip6;
#endif
} src;
union {
__be32 ip4;
#if IS_ENABLED(CONFIG_IPV6)
struct in6_addr ip6;
#endif
unsigned char mac_addr[ETH_ALEN];
} dst;
__be16 proto;
__u16 vid;
};
struct br_ip_list {
struct list_head list;
struct br_ip addr;
};
#define BR_HAIRPIN_MODE BIT(0)
#define BR_BPDU_GUARD BIT(1)
#define BR_ROOT_BLOCK BIT(2)
#define BR_MULTICAST_FAST_LEAVE BIT(3)
#define BR_ADMIN_COST BIT(4)
#define BR_LEARNING BIT(5)
#define BR_FLOOD BIT(6)
#define BR_AUTO_MASK (BR_FLOOD | BR_LEARNING)
#define BR_PROMISC BIT(7)
#define BR_PROXYARP BIT(8)
#define BR_LEARNING_SYNC BIT(9)
#define BR_PROXYARP_WIFI BIT(10)
#define BR_MCAST_FLOOD BIT(11)
#define BR_MULTICAST_TO_UNICAST BIT(12)
#define BR_VLAN_TUNNEL BIT(13)
#define BR_BCAST_FLOOD BIT(14)
#define BR_NEIGH_SUPPRESS BIT(15)
#define BR_ISOLATED BIT(16)
#define BR_MRP_AWARE BIT(17)
#define BR_MRP_LOST_CONT BIT(18)
#define BR_MRP_LOST_IN_CONT BIT(19)
#define BR_DEFAULT_AGEING_TIME (300 * HZ)
extern void brioctl_set(int (*ioctl_hook)(struct net *, unsigned int, void __user *));
#if IS_ENABLED(CONFIG_BRIDGE) && IS_ENABLED(CONFIG_BRIDGE_IGMP_SNOOPING)
int br_multicast_list_adjacent(struct net_device *dev,
struct list_head *br_ip_list);
bool br_multicast_has_querier_anywhere(struct net_device *dev, int proto);
bool br_multicast_has_querier_adjacent(struct net_device *dev, int proto);
bool br_multicast_has_router_adjacent(struct net_device *dev, int proto);
bool br_multicast_enabled(const struct net_device *dev);
bool br_multicast_router(const struct net_device *dev);
#else
static inline int br_multicast_list_adjacent(struct net_device *dev,
struct list_head *br_ip_list)
{
return 0;
}
static inline bool br_multicast_has_querier_anywhere(struct net_device *dev,
int proto)
{
return false;
}
static inline bool br_multicast_has_querier_adjacent(struct net_device *dev,
int proto)
{
return false;
}
static inline bool br_multicast_has_router_adjacent(struct net_device *dev,
int proto)
{
return true;
}
static inline bool br_multicast_enabled(const struct net_device *dev)
{
return false;
}
static inline bool br_multicast_router(const struct net_device *dev)
{
return false;
}
#endif
#if IS_ENABLED(CONFIG_BRIDGE) && IS_ENABLED(CONFIG_BRIDGE_VLAN_FILTERING)
bool br_vlan_enabled(const struct net_device *dev);
int br_vlan_get_pvid(const struct net_device *dev, u16 *p_pvid);
int br_vlan_get_pvid_rcu(const struct net_device *dev, u16 *p_pvid);
int br_vlan_get_proto(const struct net_device *dev, u16 *p_proto);
int br_vlan_get_info(const struct net_device *dev, u16 vid,
struct bridge_vlan_info *p_vinfo);
#else
static inline bool br_vlan_enabled(const struct net_device *dev)
{
return false;
}
static inline int br_vlan_get_pvid(const struct net_device *dev, u16 *p_pvid)
{
return -EINVAL;
}
static inline int br_vlan_get_proto(const struct net_device *dev, u16 *p_proto)
{
return -EINVAL;
}
static inline int br_vlan_get_pvid_rcu(const struct net_device *dev, u16 *p_pvid)
{
return -EINVAL;
}
static inline int br_vlan_get_info(const struct net_device *dev, u16 vid,
struct bridge_vlan_info *p_vinfo)
{
return -EINVAL;
}
#endif
#if IS_ENABLED(CONFIG_BRIDGE)
struct net_device *br_fdb_find_port(const struct net_device *br_dev,
const unsigned char *addr,
__u16 vid);
void br_fdb_clear_offload(const struct net_device *dev, u16 vid);
bool br_port_flag_is_set(const struct net_device *dev, unsigned long flag);
u8 br_port_get_stp_state(const struct net_device *dev);
clock_t br_get_ageing_time(const struct net_device *br_dev);
#else
static inline struct net_device *
br_fdb_find_port(const struct net_device *br_dev,
const unsigned char *addr,
__u16 vid)
{
return NULL;
}
static inline void br_fdb_clear_offload(const struct net_device *dev, u16 vid)
{
}
static inline bool
br_port_flag_is_set(const struct net_device *dev, unsigned long flag)
{
return false;
}
static inline u8 br_port_get_stp_state(const struct net_device *dev)
{
return BR_STATE_DISABLED;
}
static inline clock_t br_get_ageing_time(const struct net_device *br_dev)
{
return 0;
}
#endif
#if IS_ENABLED(CONFIG_BRIDGE) && IS_ENABLED(CONFIG_NET_SWITCHDEV)
int switchdev_bridge_port_offload(struct net_device *brport_dev,
struct net_device *dev, const void *ctx,
struct notifier_block *atomic_nb,
struct notifier_block *blocking_nb,
struct netlink_ext_ack *extack);
void switchdev_bridge_port_unoffload(struct net_device *brport_dev,
const void *ctx,
struct notifier_block *atomic_nb,
struct notifier_block *blocking_nb);
#else
static inline int
switchdev_bridge_port_offload(struct net_device *brport_dev,
struct net_device *dev, const void *ctx,
struct notifier_block *atomic_nb,
struct notifier_block *blocking_nb,
struct netlink_ext_ack *extack)
{
return -EINVAL;
}
static inline void
switchdev_bridge_port_unoffload(struct net_device *brport_dev,
const void *ctx,
struct notifier_block *atomic_nb,
struct notifier_block *blocking_nb)
{
}
#endif
#endif
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