sched_ext: Maintain an online cid mask in the scheduler arenagrafted

Schedulers on the default cid mapping treat [0, nr_online_cids) as the
online set and restart on hotplug. Schedulers that install their own mapping
with scx_bpf_cid_override() have no way to learn which cids are online: the
count no longer identifies members and the CPU-form cpumask is unusable from
cid programs. This is an obvious hole in the cid API.

Add scx_bpf_online_cmask(), a kernel-maintained cmask in the scheduler's
arena, allocated alongside the per-CPU scratch masks and populated after the
cid mapping is finalized and before ops.init(), for child schedulers too.
The pointer stays valid through ops.exit() with no reference to take. It is
the arena offset as a void pointer, the same form struct_ops arena arguments
arrive in. The verifier types the void return as a scalar for the program's
arena cast.

The mask follows the SCX hotplug notifications: seeded from cpu_active_mask
and updated before ops.cid_online/offline() runs, so it lags cpu_online_mask
only inside a hotplug transition. Updates walk the scheduler list under the
lock that also serializes unlinking. Reads are live, not atomic snapshots.
Root initialization excludes hotplug.

v2: Reworded the getter kerneldoc (Andrea Righi).

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>

1 files changed, 529 insertions, 0 deletions

diff --git a/include/net/switchdev.h b/include/net/switchdev.h
new file mode 100644
index 000000000..ee5007064
--- /dev/null
+++ b/include/net/switchdev.h
@@ -0,0 +1,529 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * include/net/switchdev.h - Switch device API
+ * Copyright (c) 2014-2015 Jiri Pirko <jiri@resnulli.us>
+ * Copyright (c) 2014-2015 Scott Feldman <sfeldma@gmail.com>
+ */
+#ifndef _LINUX_SWITCHDEV_H_
+#define _LINUX_SWITCHDEV_H_
+
+#include <linux/netdevice.h>
+#include <linux/notifier.h>
+#include <linux/list.h>
+#include <net/ip_fib.h>
+
+#define SWITCHDEV_F_NO_RECURSE		BIT(0)
+#define SWITCHDEV_F_SKIP_EOPNOTSUPP	BIT(1)
+#define SWITCHDEV_F_DEFER		BIT(2)
+#define SWITCHDEV_F_NO_FOREIGN		BIT(3)
+
+enum switchdev_attr_id {
+	SWITCHDEV_ATTR_ID_UNDEFINED,
+	SWITCHDEV_ATTR_ID_PORT_STP_STATE,
+	SWITCHDEV_ATTR_ID_PORT_MST_STATE,
+	SWITCHDEV_ATTR_ID_PORT_BRIDGE_FLAGS,
+	SWITCHDEV_ATTR_ID_PORT_PRE_BRIDGE_FLAGS,
+	SWITCHDEV_ATTR_ID_PORT_MROUTER,
+	SWITCHDEV_ATTR_ID_BRIDGE_AGEING_TIME,
+	SWITCHDEV_ATTR_ID_BRIDGE_VLAN_FILTERING,
+	SWITCHDEV_ATTR_ID_BRIDGE_VLAN_PROTOCOL,
+	SWITCHDEV_ATTR_ID_BRIDGE_MC_DISABLED,
+	SWITCHDEV_ATTR_ID_BRIDGE_MROUTER,
+	SWITCHDEV_ATTR_ID_BRIDGE_MST,
+	SWITCHDEV_ATTR_ID_MRP_PORT_ROLE,
+	SWITCHDEV_ATTR_ID_VLAN_MSTI,
+};
+
+struct switchdev_mst_state {
+	u16 msti;
+	u8 state;
+};
+
+struct switchdev_brport_flags {
+	unsigned long val;
+	unsigned long mask;
+};
+
+struct switchdev_vlan_msti {
+	u16 vid;
+	u16 msti;
+};
+
+struct switchdev_attr {
+	struct net_device *orig_dev;
+	enum switchdev_attr_id id;
+	u32 flags;
+	void *complete_priv;
+	void (*complete)(struct net_device *dev, int err, void *priv);
+	union {
+		u8 stp_state;				/* PORT_STP_STATE */
+		struct switchdev_mst_state mst_state;	/* PORT_MST_STATE */
+		struct switchdev_brport_flags brport_flags; /* PORT_BRIDGE_FLAGS */
+		bool mrouter;				/* PORT_MROUTER */
+		clock_t ageing_time;			/* BRIDGE_AGEING_TIME */
+		bool vlan_filtering;			/* BRIDGE_VLAN_FILTERING */
+		u16 vlan_protocol;			/* BRIDGE_VLAN_PROTOCOL */
+		bool mst;				/* BRIDGE_MST */
+		bool mc_disabled;			/* MC_DISABLED */
+		u8 mrp_port_role;			/* MRP_PORT_ROLE */
+		struct switchdev_vlan_msti vlan_msti;	/* VLAN_MSTI */
+	} u;
+};
+
+enum switchdev_obj_id {
+	SWITCHDEV_OBJ_ID_UNDEFINED,
+	SWITCHDEV_OBJ_ID_PORT_VLAN,
+	SWITCHDEV_OBJ_ID_PORT_MDB,
+	SWITCHDEV_OBJ_ID_HOST_MDB,
+	SWITCHDEV_OBJ_ID_MRP,
+	SWITCHDEV_OBJ_ID_RING_TEST_MRP,
+	SWITCHDEV_OBJ_ID_RING_ROLE_MRP,
+	SWITCHDEV_OBJ_ID_RING_STATE_MRP,
+	SWITCHDEV_OBJ_ID_IN_TEST_MRP,
+	SWITCHDEV_OBJ_ID_IN_ROLE_MRP,
+	SWITCHDEV_OBJ_ID_IN_STATE_MRP,
+};
+
+struct switchdev_obj {
+	struct list_head list;
+	struct net_device *orig_dev;
+	enum switchdev_obj_id id;
+	u32 flags;
+	void *complete_priv;
+	void (*complete)(struct net_device *dev, int err, void *priv);
+};
+
+/* SWITCHDEV_OBJ_ID_PORT_VLAN */
+struct switchdev_obj_port_vlan {
+	struct switchdev_obj obj;
+	u16 flags;
+	u16 vid;
+	/* If set, the notifier signifies a change of one of the following
+	 * flags for a VLAN that already exists:
+	 * - BRIDGE_VLAN_INFO_PVID
+	 * - BRIDGE_VLAN_INFO_UNTAGGED
+	 * Entries with BRIDGE_VLAN_INFO_BRENTRY unset are not notified at all.
+	 */
+	bool changed;
+};
+
+#define SWITCHDEV_OBJ_PORT_VLAN(OBJ) \
+	container_of((OBJ), struct switchdev_obj_port_vlan, obj)
+
+/* SWITCHDEV_OBJ_ID_PORT_MDB */
+struct switchdev_obj_port_mdb {
+	struct switchdev_obj obj;
+	unsigned char addr[ETH_ALEN];
+	u16 vid;
+};
+
+#define SWITCHDEV_OBJ_PORT_MDB(OBJ) \
+	container_of((OBJ), struct switchdev_obj_port_mdb, obj)
+
+
+/* SWITCHDEV_OBJ_ID_MRP */
+struct switchdev_obj_mrp {
+	struct switchdev_obj obj;
+	struct net_device *p_port;
+	struct net_device *s_port;
+	u32 ring_id;
+	u16 prio;
+};
+
+#define SWITCHDEV_OBJ_MRP(OBJ) \
+	container_of((OBJ), struct switchdev_obj_mrp, obj)
+
+/* SWITCHDEV_OBJ_ID_RING_TEST_MRP */
+struct switchdev_obj_ring_test_mrp {
+	struct switchdev_obj obj;
+	/* The value is in us and a value of 0 represents to stop */
+	u32 interval;
+	u8 max_miss;
+	u32 ring_id;
+	u32 period;
+	bool monitor;
+};
+
+#define SWITCHDEV_OBJ_RING_TEST_MRP(OBJ) \
+	container_of((OBJ), struct switchdev_obj_ring_test_mrp, obj)
+
+/* SWICHDEV_OBJ_ID_RING_ROLE_MRP */
+struct switchdev_obj_ring_role_mrp {
+	struct switchdev_obj obj;
+	u8 ring_role;
+	u32 ring_id;
+	u8 sw_backup;
+};
+
+#define SWITCHDEV_OBJ_RING_ROLE_MRP(OBJ) \
+	container_of((OBJ), struct switchdev_obj_ring_role_mrp, obj)
+
+struct switchdev_obj_ring_state_mrp {
+	struct switchdev_obj obj;
+	u8 ring_state;
+	u32 ring_id;
+};
+
+#define SWITCHDEV_OBJ_RING_STATE_MRP(OBJ) \
+	container_of((OBJ), struct switchdev_obj_ring_state_mrp, obj)
+
+/* SWITCHDEV_OBJ_ID_IN_TEST_MRP */
+struct switchdev_obj_in_test_mrp {
+	struct switchdev_obj obj;
+	/* The value is in us and a value of 0 represents to stop */
+	u32 interval;
+	u32 in_id;
+	u32 period;
+	u8 max_miss;
+};
+
+#define SWITCHDEV_OBJ_IN_TEST_MRP(OBJ) \
+	container_of((OBJ), struct switchdev_obj_in_test_mrp, obj)
+
+/* SWICHDEV_OBJ_ID_IN_ROLE_MRP */
+struct switchdev_obj_in_role_mrp {
+	struct switchdev_obj obj;
+	struct net_device *i_port;
+	u32 ring_id;
+	u16 in_id;
+	u8 in_role;
+	u8 sw_backup;
+};
+
+#define SWITCHDEV_OBJ_IN_ROLE_MRP(OBJ) \
+	container_of((OBJ), struct switchdev_obj_in_role_mrp, obj)
+
+struct switchdev_obj_in_state_mrp {
+	struct switchdev_obj obj;
+	u32 in_id;
+	u8 in_state;
+};
+
+#define SWITCHDEV_OBJ_IN_STATE_MRP(OBJ) \
+	container_of((OBJ), struct switchdev_obj_in_state_mrp, obj)
+
+struct switchdev_brport {
+	struct net_device *dev;
+	const void *ctx;
+	struct notifier_block *atomic_nb;
+	struct notifier_block *blocking_nb;
+	bool tx_fwd_offload;
+};
+
+enum switchdev_notifier_type {
+	SWITCHDEV_FDB_ADD_TO_BRIDGE = 1,
+	SWITCHDEV_FDB_DEL_TO_BRIDGE,
+	SWITCHDEV_FDB_ADD_TO_DEVICE,
+	SWITCHDEV_FDB_DEL_TO_DEVICE,
+	SWITCHDEV_FDB_OFFLOADED,
+	SWITCHDEV_FDB_FLUSH_TO_BRIDGE,
+
+	SWITCHDEV_PORT_OBJ_ADD, /* Blocking. */
+	SWITCHDEV_PORT_OBJ_DEL, /* Blocking. */
+	SWITCHDEV_PORT_ATTR_SET, /* May be blocking . */
+
+	SWITCHDEV_VXLAN_FDB_ADD_TO_BRIDGE,
+	SWITCHDEV_VXLAN_FDB_DEL_TO_BRIDGE,
+	SWITCHDEV_VXLAN_FDB_ADD_TO_DEVICE,
+	SWITCHDEV_VXLAN_FDB_DEL_TO_DEVICE,
+	SWITCHDEV_VXLAN_FDB_OFFLOADED,
+
+	SWITCHDEV_BRPORT_OFFLOADED,
+	SWITCHDEV_BRPORT_UNOFFLOADED,
+	SWITCHDEV_BRPORT_REPLAY,
+};
+
+struct switchdev_notifier_info {
+	struct net_device *dev;
+	struct netlink_ext_ack *extack;
+	const void *ctx;
+};
+
+/* Remember to update br_switchdev_fdb_populate() when adding
+ * new members to this structure
+ */
+struct switchdev_notifier_fdb_info {
+	struct switchdev_notifier_info info; /* must be first */
+	const unsigned char *addr;
+	u16 vid;
+	u8 added_by_user:1,
+	   is_local:1,
+	   locked:1,
+	   offloaded:1;
+};
+
+struct switchdev_notifier_port_obj_info {
+	struct switchdev_notifier_info info; /* must be first */
+	const struct switchdev_obj *obj;
+	bool handled;
+};
+
+struct switchdev_notifier_port_attr_info {
+	struct switchdev_notifier_info info; /* must be first */
+	const struct switchdev_attr *attr;
+	bool handled;
+};
+
+struct switchdev_notifier_brport_info {
+	struct switchdev_notifier_info info; /* must be first */
+	const struct switchdev_brport brport;
+};
+
+static inline struct net_device *
+switchdev_notifier_info_to_dev(const struct switchdev_notifier_info *info)
+{
+	return info->dev;
+}
+
+static inline struct netlink_ext_ack *
+switchdev_notifier_info_to_extack(const struct switchdev_notifier_info *info)
+{
+	return info->extack;
+}
+
+static inline bool
+switchdev_fdb_is_dynamically_learned(const struct switchdev_notifier_fdb_info *fdb_info)
+{
+	return !fdb_info->added_by_user && !fdb_info->is_local;
+}
+
+#ifdef 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,
+				  bool tx_fwd_offload,
+				  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);
+int switchdev_bridge_port_replay(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_deferred_process(void);
+int switchdev_port_attr_set(struct net_device *dev,
+			    const struct switchdev_attr *attr,
+			    struct netlink_ext_ack *extack);
+bool switchdev_port_obj_act_is_deferred(struct net_device *dev,
+					enum switchdev_notifier_type nt,
+					const struct switchdev_obj *obj);
+int switchdev_port_obj_add(struct net_device *dev,
+			   const struct switchdev_obj *obj,
+			   struct netlink_ext_ack *extack);
+int switchdev_port_obj_del(struct net_device *dev,
+			   const struct switchdev_obj *obj);
+
+int register_switchdev_notifier(struct notifier_block *nb);
+int unregister_switchdev_notifier(struct notifier_block *nb);
+int call_switchdev_notifiers(unsigned long val, struct net_device *dev,
+			     struct switchdev_notifier_info *info,
+			     struct netlink_ext_ack *extack);
+
+int register_switchdev_blocking_notifier(struct notifier_block *nb);
+int unregister_switchdev_blocking_notifier(struct notifier_block *nb);
+int call_switchdev_blocking_notifiers(unsigned long val, struct net_device *dev,
+				      struct switchdev_notifier_info *info,
+				      struct netlink_ext_ack *extack);
+
+int switchdev_handle_fdb_event_to_device(struct net_device *dev, unsigned long event,
+		const struct switchdev_notifier_fdb_info *fdb_info,
+		bool (*check_cb)(const struct net_device *dev),
+		bool (*foreign_dev_check_cb)(const struct net_device *dev,
+					     const struct net_device *foreign_dev),
+		int (*mod_cb)(struct net_device *dev, struct net_device *orig_dev,
+			      unsigned long event, const void *ctx,
+			      const struct switchdev_notifier_fdb_info *fdb_info));
+
+int switchdev_handle_port_obj_add(struct net_device *dev,
+			struct switchdev_notifier_port_obj_info *port_obj_info,
+			bool (*check_cb)(const struct net_device *dev),
+			int (*add_cb)(struct net_device *dev, const void *ctx,
+				      const struct switchdev_obj *obj,
+				      struct netlink_ext_ack *extack));
+int switchdev_handle_port_obj_add_foreign(struct net_device *dev,
+			struct switchdev_notifier_port_obj_info *port_obj_info,
+			bool (*check_cb)(const struct net_device *dev),
+			bool (*foreign_dev_check_cb)(const struct net_device *dev,
+						     const struct net_device *foreign_dev),
+			int (*add_cb)(struct net_device *dev, const void *ctx,
+				      const struct switchdev_obj *obj,
+				      struct netlink_ext_ack *extack));
+int switchdev_handle_port_obj_del(struct net_device *dev,
+			struct switchdev_notifier_port_obj_info *port_obj_info,
+			bool (*check_cb)(const struct net_device *dev),
+			int (*del_cb)(struct net_device *dev, const void *ctx,
+				      const struct switchdev_obj *obj));
+int switchdev_handle_port_obj_del_foreign(struct net_device *dev,
+			struct switchdev_notifier_port_obj_info *port_obj_info,
+			bool (*check_cb)(const struct net_device *dev),
+			bool (*foreign_dev_check_cb)(const struct net_device *dev,
+						     const struct net_device *foreign_dev),
+			int (*del_cb)(struct net_device *dev, const void *ctx,
+				      const struct switchdev_obj *obj));
+
+int switchdev_handle_port_attr_set(struct net_device *dev,
+			struct switchdev_notifier_port_attr_info *port_attr_info,
+			bool (*check_cb)(const struct net_device *dev),
+			int (*set_cb)(struct net_device *dev, const void *ctx,
+				      const struct switchdev_attr *attr,
+				      struct netlink_ext_ack *extack));
+#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,
+			      bool tx_fwd_offload,
+			      struct netlink_ext_ack *extack)
+{
+	return -EOPNOTSUPP;
+}
+
+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)
+{
+}
+
+static inline void switchdev_deferred_process(void)
+{
+}
+
+static inline int switchdev_port_attr_set(struct net_device *dev,
+					  const struct switchdev_attr *attr,
+					  struct netlink_ext_ack *extack)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int switchdev_port_obj_add(struct net_device *dev,
+					 const struct switchdev_obj *obj,
+					 struct netlink_ext_ack *extack)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int switchdev_port_obj_del(struct net_device *dev,
+					 const struct switchdev_obj *obj)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int register_switchdev_notifier(struct notifier_block *nb)
+{
+	return 0;
+}
+
+static inline int unregister_switchdev_notifier(struct notifier_block *nb)
+{
+	return 0;
+}
+
+static inline int call_switchdev_notifiers(unsigned long val,
+					   struct net_device *dev,
+					   struct switchdev_notifier_info *info,
+					   struct netlink_ext_ack *extack)
+{
+	return NOTIFY_DONE;
+}
+
+static inline int
+register_switchdev_blocking_notifier(struct notifier_block *nb)
+{
+	return 0;
+}
+
+static inline int
+unregister_switchdev_blocking_notifier(struct notifier_block *nb)
+{
+	return 0;
+}
+
+static inline int
+call_switchdev_blocking_notifiers(unsigned long val,
+				  struct net_device *dev,
+				  struct switchdev_notifier_info *info,
+				  struct netlink_ext_ack *extack)
+{
+	return NOTIFY_DONE;
+}
+
+static inline int
+switchdev_handle_fdb_event_to_device(struct net_device *dev, unsigned long event,
+		const struct switchdev_notifier_fdb_info *fdb_info,
+		bool (*check_cb)(const struct net_device *dev),
+		bool (*foreign_dev_check_cb)(const struct net_device *dev,
+					     const struct net_device *foreign_dev),
+		int (*mod_cb)(struct net_device *dev, struct net_device *orig_dev,
+			      unsigned long event, const void *ctx,
+			      const struct switchdev_notifier_fdb_info *fdb_info))
+{
+	return 0;
+}
+
+static inline int
+switchdev_handle_port_obj_add(struct net_device *dev,
+			struct switchdev_notifier_port_obj_info *port_obj_info,
+			bool (*check_cb)(const struct net_device *dev),
+			int (*add_cb)(struct net_device *dev, const void *ctx,
+				      const struct switchdev_obj *obj,
+				      struct netlink_ext_ack *extack))
+{
+	return 0;
+}
+
+static inline int switchdev_handle_port_obj_add_foreign(struct net_device *dev,
+			struct switchdev_notifier_port_obj_info *port_obj_info,
+			bool (*check_cb)(const struct net_device *dev),
+			bool (*foreign_dev_check_cb)(const struct net_device *dev,
+						     const struct net_device *foreign_dev),
+			int (*add_cb)(struct net_device *dev, const void *ctx,
+				      const struct switchdev_obj *obj,
+				      struct netlink_ext_ack *extack))
+{
+	return 0;
+}
+
+static inline int
+switchdev_handle_port_obj_del(struct net_device *dev,
+			struct switchdev_notifier_port_obj_info *port_obj_info,
+			bool (*check_cb)(const struct net_device *dev),
+			int (*del_cb)(struct net_device *dev, const void *ctx,
+				      const struct switchdev_obj *obj))
+{
+	return 0;
+}
+
+static inline int
+switchdev_handle_port_obj_del_foreign(struct net_device *dev,
+			struct switchdev_notifier_port_obj_info *port_obj_info,
+			bool (*check_cb)(const struct net_device *dev),
+			bool (*foreign_dev_check_cb)(const struct net_device *dev,
+						     const struct net_device *foreign_dev),
+			int (*del_cb)(struct net_device *dev, const void *ctx,
+				      const struct switchdev_obj *obj))
+{
+	return 0;
+}
+
+static inline int
+switchdev_handle_port_attr_set(struct net_device *dev,
+			struct switchdev_notifier_port_attr_info *port_attr_info,
+			bool (*check_cb)(const struct net_device *dev),
+			int (*set_cb)(struct net_device *dev, const void *ctx,
+				      const struct switchdev_attr *attr,
+				      struct netlink_ext_ack *extack))
+{
+	return 0;
+}
+#endif
+
+#endif /* _LINUX_SWITCHDEV_H_ */