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linux-next/include/linux/if_bridge.h
Vladimir Oltean 957e2235e5 net: make switchdev_bridge_port_{,unoffload} loosely coupled with the bridge 
With the introduction of explicit offloading API in switchdev in commit
2f5dc00f7a ("net: bridge: switchdev: let drivers inform which bridge
ports are offloaded"), we started having Ethernet switch drivers calling
directly into a function exported by net/bridge/br_switchdev.c, which is
a function exported by the bridge driver.

This means that drivers that did not have an explicit dependency on the
bridge before, like cpsw and am65-cpsw, now do - otherwise it is not
possible to call a symbol exported by a driver that can be built as
module unless you are a module too.

There was an attempt to solve the dependency issue in the form of commit
b0e8181762 ("net: build all switchdev drivers as modules when the
bridge is a module"). Grygorii Strashko, however, says about it:

| In my opinion, the problem is a bit bigger here than just fixing the
| build :(
|
| In case, of ^cpsw the switchdev mode is kinda optional and in many
| cases (especially for testing purposes, NFS) the multi-mac mode is
| still preferable mode.
|
| There were no such tight dependency between switchdev drivers and
| bridge core before and switchdev serviced as independent, notification
| based layer between them, so ^cpsw still can be "Y" and bridge can be
| "M". Now for mostly every kernel build configuration the CONFIG_BRIDGE
| will need to be set as "Y", or we will have to update drivers to
| support build with BRIDGE=n and maintain separate builds for
| networking vs non-networking testing.  But is this enough?  Wouldn't
| it cause 'chain reaction' required to add more and more "Y" options
| (like CONFIG_VLAN_8021Q)?
|
| PS. Just to be sure we on the same page - ARM builds will be forced
| (with this patch) to have CONFIG_TI_CPSW_SWITCHDEV=m and so all our
| automation testing will just fail with omap2plus_defconfig.

In the light of this, it would be desirable for some configurations to
avoid dependencies between switchdev drivers and the bridge, and have
the switchdev mode as completely optional within the driver.

Arnd Bergmann also tried to write a patch which better expressed the
build time dependency for Ethernet switch drivers where the switchdev
support is optional, like cpsw/am65-cpsw, and this made the drivers
follow the bridge (compile as module if the bridge is a module) only if
the optional switchdev support in the driver was enabled in the first
place:
https://patchwork.kernel.org/project/netdevbpf/patch/20210802144813.1152762-1-arnd@kernel.org/

but this still did not solve the fact that cpsw and am65-cpsw now must
be built as modules when the bridge is a module - it just expressed
correctly that optional dependency. But the new behavior is an apparent
regression from Grygorii's perspective.

So to support the use case where the Ethernet driver is built-in,
NET_SWITCHDEV (a bool option) is enabled, and the bridge is a module, we
need a framework that can handle the possible absence of the bridge from
the running system, i.e. runtime bloatware as opposed to build-time
bloatware.

Luckily we already have this framework, since switchdev has been using
it extensively. Events from the bridge side are transmitted to the
driver side using notifier chains - this was originally done so that
unrelated drivers could snoop for events emitted by the bridge towards
ports that are implemented by other drivers (think of a switch driver
with LAG offload that listens for switchdev events on a bonding/team
interface that it offloads).

There are also events which are transmitted from the driver side to the
bridge side, which again are modeled using notifiers.
SWITCHDEV_FDB_ADD_TO_BRIDGE is an example of this, and deals with
notifying the bridge that a MAC address has been dynamically learned.
So there is a precedent we can use for modeling the new framework.

The difference compared to SWITCHDEV_FDB_ADD_TO_BRIDGE is that the work
that the bridge needs to do when a port becomes offloaded is blocking in
its nature: replay VLANs, MDBs etc. The calling context is indeed
blocking (we are under rtnl_mutex), but the existing switchdev
notification chain that the bridge is subscribed to is only the atomic
one. So we need to subscribe the bridge to the blocking switchdev
notification chain too.

This patch:
- keeps the driver-side perception of the switchdev_bridge_port_{,un}offload
  unchanged
- moves the implementation of switchdev_bridge_port_{,un}offload from
  the bridge module into the switchdev module.
- makes everybody that is subscribed to the switchdev blocking notifier
  chain "hear" offload & unoffload events
- makes the bridge driver subscribe and handle those events
- moves the bridge driver's handling of those events into 2 new
  functions called br_switchdev_port_{,un}offload. These functions
  contain in fact the core of the logic that was previously in
  switchdev_bridge_port_{,un}offload, just that now we go through an
  extra indirection layer to reach them.

Unlike all the other switchdev notification structures, the structure
used to carry the bridge port information, struct
switchdev_notifier_brport_info, does not contain a "bool handled".
This is because in the current usage pattern, we always know that a
switchdev bridge port offloading event will be handled by the bridge,
because the switchdev_bridge_port_offload() call was initiated by a
NETDEV_CHANGEUPPER event in the first place, where info->upper_dev is a
bridge. So if the bridge wasn't loaded, then the CHANGEUPPER event
couldn't have happened.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Tested-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-08-04 12:35:07 +01:00

194 lines
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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_TX_FWD_OFFLOAD BIT(20)
#define BR_DEFAULT_AGEING_TIME (300 * HZ)
struct net_bridge;
void brioctl_set(int (*hook)(struct net *net, struct net_bridge *br,
unsigned int cmd, struct ifreq *ifr,
void __user *uarg));
int br_ioctl_call(struct net *net, struct net_bridge *br, unsigned int cmd,
struct ifreq *ifr, void __user *uarg);
#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);
int br_vlan_get_info_rcu(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;
}
static inline int br_vlan_get_info_rcu(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
#endif
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