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, 249 insertions, 0 deletions

diff --git a/drivers/input/mouse/psmouse.h b/drivers/input/mouse/psmouse.h
new file mode 100644
index 000000000..90ed8cd15
--- /dev/null
+++ b/drivers/input/mouse/psmouse.h
@@ -0,0 +1,249 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _PSMOUSE_H
+#define _PSMOUSE_H
+
+#define PSMOUSE_OOB_NONE	0x00
+#define PSMOUSE_OOB_EXTRA_BTNS	0x01
+
+#define PSMOUSE_CMD_SETSCALE11	0x00e6
+#define PSMOUSE_CMD_SETSCALE21	0x00e7
+#define PSMOUSE_CMD_SETRES	0x10e8
+#define PSMOUSE_CMD_GETINFO	0x03e9
+#define PSMOUSE_CMD_SETSTREAM	0x00ea
+#define PSMOUSE_CMD_SETPOLL	0x00f0
+#define PSMOUSE_CMD_POLL	0x00eb	/* caller sets number of bytes to receive */
+#define PSMOUSE_CMD_RESET_WRAP	0x00ec
+#define PSMOUSE_CMD_GETID	0x02f2
+#define PSMOUSE_CMD_SETRATE	0x10f3
+#define PSMOUSE_CMD_ENABLE	0x00f4
+#define PSMOUSE_CMD_DISABLE	0x00f5
+#define PSMOUSE_CMD_RESET_DIS	0x00f6
+#define PSMOUSE_CMD_RESET_BAT	0x02ff
+
+#define PSMOUSE_RET_BAT		0xaa
+#define PSMOUSE_RET_ID		0x00
+#define PSMOUSE_RET_ACK		0xfa
+#define PSMOUSE_RET_NAK		0xfe
+
+enum psmouse_state {
+	PSMOUSE_IGNORE,
+	PSMOUSE_INITIALIZING,
+	PSMOUSE_RESYNCING,
+	PSMOUSE_CMD_MODE,
+	PSMOUSE_ACTIVATED,
+};
+
+/* psmouse protocol handler return codes */
+typedef enum {
+	PSMOUSE_BAD_DATA,
+	PSMOUSE_GOOD_DATA,
+	PSMOUSE_FULL_PACKET
+} psmouse_ret_t;
+
+enum psmouse_scale {
+	PSMOUSE_SCALE11,
+	PSMOUSE_SCALE21
+};
+
+enum psmouse_type {
+	PSMOUSE_NONE,
+	PSMOUSE_PS2,
+	PSMOUSE_PS2PP,
+	PSMOUSE_THINKPS,
+	PSMOUSE_GENPS,
+	PSMOUSE_IMPS,
+	PSMOUSE_IMEX,
+	PSMOUSE_SYNAPTICS,
+	PSMOUSE_ALPS,
+	PSMOUSE_LIFEBOOK,
+	PSMOUSE_TRACKPOINT,
+	PSMOUSE_TOUCHKIT_PS2,
+	PSMOUSE_CORTRON,
+	PSMOUSE_HGPK,		/* No longer used */
+	PSMOUSE_ELANTECH,
+	PSMOUSE_FSP,
+	PSMOUSE_SYNAPTICS_RELATIVE,
+	PSMOUSE_CYPRESS,
+	PSMOUSE_FOCALTECH,
+	PSMOUSE_VMMOUSE,
+	PSMOUSE_BYD,
+	PSMOUSE_SYNAPTICS_SMBUS,
+	PSMOUSE_ELANTECH_SMBUS,
+	PSMOUSE_AUTO		/* This one should always be last */
+};
+
+struct psmouse;
+
+struct psmouse_protocol {
+	enum psmouse_type type;
+	bool maxproto;
+	bool ignore_parity; /* Protocol should ignore parity errors from KBC */
+	bool try_passthru; /* Try protocol also on passthrough ports */
+	bool smbus_companion; /* "Protocol" is a stub, device is on SMBus */
+	const char *name;
+	const char *alias;
+	int (*detect)(struct psmouse *, bool);
+	int (*init)(struct psmouse *);
+};
+
+struct psmouse {
+	void *private;
+	struct input_dev *dev;
+	struct ps2dev ps2dev;
+	struct work_struct resync_work;
+	const char *vendor;
+	const char *name;
+	const struct psmouse_protocol *protocol;
+	unsigned char packet[8];
+	unsigned char badbyte;
+	unsigned char pktcnt;
+	unsigned char pktsize;
+	unsigned char oob_data_type;
+	unsigned char extra_buttons;
+	bool acks_disable_command;
+	unsigned int model;
+	unsigned long last;
+	unsigned long out_of_sync_cnt;
+	unsigned long num_resyncs;
+	enum psmouse_state state;
+	char devname[64];
+	char phys[32];
+
+	unsigned int rate;
+	unsigned int resolution;
+	unsigned int resetafter;
+	unsigned int resync_time;
+	bool smartscroll;	/* Logitech only */
+
+	psmouse_ret_t (*protocol_handler)(struct psmouse *psmouse);
+	void (*set_rate)(struct psmouse *psmouse, unsigned int rate);
+	void (*set_resolution)(struct psmouse *psmouse, unsigned int resolution);
+	void (*set_scale)(struct psmouse *psmouse, enum psmouse_scale scale);
+
+	int (*reconnect)(struct psmouse *psmouse);
+	int (*fast_reconnect)(struct psmouse *psmouse);
+	void (*disconnect)(struct psmouse *psmouse);
+	void (*cleanup)(struct psmouse *psmouse);
+	int (*poll)(struct psmouse *psmouse);
+
+	void (*pt_activate)(struct psmouse *psmouse);
+	void (*pt_deactivate)(struct psmouse *psmouse);
+};
+
+struct psmouse *psmouse_from_serio(struct serio *serio);
+
+int psmouse_reset(struct psmouse *psmouse);
+void psmouse_set_state(struct psmouse *psmouse, enum psmouse_state new_state);
+void psmouse_set_resolution(struct psmouse *psmouse, unsigned int resolution);
+psmouse_ret_t psmouse_process_byte(struct psmouse *psmouse);
+int psmouse_activate(struct psmouse *psmouse);
+int psmouse_deactivate(struct psmouse *psmouse);
+bool psmouse_matches_pnp_id(struct psmouse *psmouse, const char * const ids[]);
+
+void psmouse_report_standard_buttons(struct input_dev *, u8 buttons);
+void psmouse_report_standard_motion(struct input_dev *, u8 *packet);
+void psmouse_report_standard_packet(struct input_dev *, u8 *packet);
+
+struct psmouse_attribute {
+	struct device_attribute dattr;
+	void *data;
+	ssize_t (*show)(struct psmouse *psmouse, void *data, char *buf);
+	ssize_t (*set)(struct psmouse *psmouse, void *data,
+			const char *buf, size_t count);
+	bool protect;
+};
+#define to_psmouse_attr(a)	container_of((a), struct psmouse_attribute, dattr)
+
+ssize_t psmouse_attr_show_helper(struct device *dev, struct device_attribute *attr,
+				 char *buf);
+ssize_t psmouse_attr_set_helper(struct device *dev, struct device_attribute *attr,
+				const char *buf, size_t count);
+
+#define __PSMOUSE_DEFINE_ATTR_VAR(_name, _mode, _data, _show, _set, _protect)	\
+static struct psmouse_attribute psmouse_attr_##_name = {			\
+	.dattr	= {								\
+		.attr	= {							\
+			.name	= __stringify(_name),				\
+			.mode	= _mode,					\
+		},								\
+		.show	= psmouse_attr_show_helper,				\
+		.store	= psmouse_attr_set_helper,				\
+	},									\
+	.data	= _data,							\
+	.show	= _show,							\
+	.set	= _set,								\
+	.protect = _protect,							\
+}
+
+#define __PSMOUSE_DEFINE_ATTR(_name, _mode, _data, _show, _set, _protect)	\
+	static ssize_t _show(struct psmouse *, void *, char *);			\
+	static ssize_t _set(struct psmouse *, void *, const char *, size_t);	\
+	__PSMOUSE_DEFINE_ATTR_VAR(_name, _mode, _data, _show, _set, _protect)
+
+#define PSMOUSE_DEFINE_ATTR(_name, _mode, _data, _show, _set)			\
+	__PSMOUSE_DEFINE_ATTR(_name, _mode, _data, _show, _set, true)
+
+#define PSMOUSE_DEFINE_RO_ATTR(_name, _mode, _data, _show)			\
+	static ssize_t _show(struct psmouse *, void *, char *);			\
+	__PSMOUSE_DEFINE_ATTR_VAR(_name, _mode, _data, _show, NULL, true)
+
+#define PSMOUSE_DEFINE_WO_ATTR(_name, _mode, _data, _set)			\
+	static ssize_t _set(struct psmouse *, void *, const char *, size_t);	\
+	__PSMOUSE_DEFINE_ATTR_VAR(_name, _mode, _data, NULL, _set, true)
+
+#ifndef psmouse_fmt
+#define psmouse_fmt(fmt)	KBUILD_BASENAME ": " fmt
+#endif
+
+#define psmouse_dbg(psmouse, format, ...)		\
+	dev_dbg(&(psmouse)->ps2dev.serio->dev,		\
+		psmouse_fmt(format), ##__VA_ARGS__)
+#define psmouse_info(psmouse, format, ...)		\
+	dev_info(&(psmouse)->ps2dev.serio->dev,		\
+		 psmouse_fmt(format), ##__VA_ARGS__)
+#define psmouse_warn(psmouse, format, ...)		\
+	dev_warn(&(psmouse)->ps2dev.serio->dev,		\
+		 psmouse_fmt(format), ##__VA_ARGS__)
+#define psmouse_err(psmouse, format, ...)		\
+	dev_err(&(psmouse)->ps2dev.serio->dev,		\
+		psmouse_fmt(format), ##__VA_ARGS__)
+#define psmouse_notice(psmouse, format, ...)		\
+	dev_notice(&(psmouse)->ps2dev.serio->dev,	\
+		   psmouse_fmt(format), ##__VA_ARGS__)
+#define psmouse_printk(level, psmouse, format, ...)	\
+	dev_printk(level,				\
+		   &(psmouse)->ps2dev.serio->dev,	\
+		   psmouse_fmt(format), ##__VA_ARGS__)
+
+#ifdef CONFIG_MOUSE_PS2_SMBUS
+
+int psmouse_smbus_module_init(void);
+void psmouse_smbus_module_exit(void);
+
+struct i2c_board_info;
+
+int psmouse_smbus_init(struct psmouse *psmouse,
+		       const struct i2c_board_info *board,
+		       const void *pdata, size_t pdata_size,
+		       bool need_deactivate,
+		       bool leave_breadcrumbs);
+void psmouse_smbus_cleanup(struct psmouse *psmouse);
+
+#else /* !CONFIG_MOUSE_PS2_SMBUS */
+
+static inline int psmouse_smbus_module_init(void)
+{
+	return 0;
+}
+
+static inline void psmouse_smbus_module_exit(void)
+{
+}
+
+static inline void psmouse_smbus_cleanup(struct psmouse *psmouse)
+{
+}
+
+#endif /* CONFIG_MOUSE_PS2_SMBUS */
+
+#endif /* _PSMOUSE_H */