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, 294 insertions, 0 deletions

diff --git a/drivers/input/joystick/interact.c b/drivers/input/joystick/interact.c
new file mode 100644
index 000000000..507cec36b
--- /dev/null
+++ b/drivers/input/joystick/interact.c
@@ -0,0 +1,294 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Copyright (c) 2001 Vojtech Pavlik
+ *
+ *  Based on the work of:
+ *	Toby Deshane
+ */
+
+/*
+ * InterAct digital gamepad/joystick driver for Linux
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/gameport.h>
+#include <linux/input.h>
+#include <linux/jiffies.h>
+
+#define DRIVER_DESC	"InterAct digital joystick driver"
+
+MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
+
+#define INTERACT_MAX_START	600	/* 400 us */
+#define INTERACT_MAX_STROBE	60	/* 40 us */
+#define INTERACT_MAX_LENGTH	32	/* 32 bits */
+
+#define INTERACT_TYPE_HHFX	0	/* HammerHead/FX */
+#define INTERACT_TYPE_PP8D	1	/* ProPad 8 */
+
+struct interact {
+	struct gameport *gameport;
+	struct input_dev *dev;
+	int bads;
+	int reads;
+	unsigned char type;
+	unsigned char length;
+	char phys[32];
+};
+
+static short interact_abs_hhfx[] =
+	{ ABS_RX, ABS_RY, ABS_X, ABS_Y, ABS_HAT0X, ABS_HAT0Y, -1 };
+static short interact_abs_pp8d[] =
+	{ ABS_X, ABS_Y, -1 };
+
+static short interact_btn_hhfx[] =
+	{ BTN_TR, BTN_X, BTN_Y, BTN_Z, BTN_A, BTN_B, BTN_C, BTN_TL, BTN_TL2, BTN_TR2, BTN_MODE, BTN_SELECT, -1 };
+static short interact_btn_pp8d[] =
+	{ BTN_C, BTN_TL, BTN_TR, BTN_A, BTN_B, BTN_Y, BTN_Z, BTN_X, -1 };
+
+struct interact_type {
+	int id;
+	short *abs;
+	short *btn;
+	char *name;
+	unsigned char length;
+	unsigned char b8;
+};
+
+static struct interact_type interact_type[] = {
+	{ 0x6202, interact_abs_hhfx, interact_btn_hhfx, "InterAct HammerHead/FX",    32, 4 },
+	{ 0x53f8, interact_abs_pp8d, interact_btn_pp8d, "InterAct ProPad 8 Digital", 16, 0 },
+	{ 0 }};
+
+/*
+ * interact_read_packet() reads and InterAct joystick data.
+ */
+
+static int interact_read_packet(struct gameport *gameport, int length, u32 *data)
+{
+	unsigned long flags;
+	unsigned char u, v;
+	unsigned int t, s;
+	int i;
+
+	i = 0;
+	data[0] = data[1] = data[2] = 0;
+	t = gameport_time(gameport, INTERACT_MAX_START);
+	s = gameport_time(gameport, INTERACT_MAX_STROBE);
+
+	local_irq_save(flags);
+	gameport_trigger(gameport);
+	v = gameport_read(gameport);
+
+	while (t > 0 && i < length) {
+		t--;
+		u = v; v = gameport_read(gameport);
+		if (v & ~u & 0x40) {
+			data[0] = (data[0] << 1) | ((v >> 4) & 1);
+			data[1] = (data[1] << 1) | ((v >> 5) & 1);
+			data[2] = (data[2] << 1) | ((v >> 7) & 1);
+			i++;
+			t = s;
+		}
+	}
+
+	local_irq_restore(flags);
+
+	return i;
+}
+
+/*
+ * interact_poll() reads and analyzes InterAct joystick data.
+ */
+
+static void interact_poll(struct gameport *gameport)
+{
+	struct interact *interact = gameport_get_drvdata(gameport);
+	struct input_dev *dev = interact->dev;
+	u32 data[3];
+	int i;
+
+	interact->reads++;
+
+	if (interact_read_packet(interact->gameport, interact->length, data) < interact->length) {
+		interact->bads++;
+	} else {
+
+		for (i = 0; i < 3; i++)
+			data[i] <<= INTERACT_MAX_LENGTH - interact->length;
+
+		switch (interact->type) {
+
+			case INTERACT_TYPE_HHFX:
+
+				for (i = 0; i < 4; i++)
+					input_report_abs(dev, interact_abs_hhfx[i], (data[i & 1] >> ((i >> 1) << 3)) & 0xff);
+
+				for (i = 0; i < 2; i++)
+					input_report_abs(dev, ABS_HAT0Y - i,
+						((data[1] >> ((i << 1) + 17)) & 1)  - ((data[1] >> ((i << 1) + 16)) & 1));
+
+				for (i = 0; i < 8; i++)
+					input_report_key(dev, interact_btn_hhfx[i], (data[0] >> (i + 16)) & 1);
+
+				for (i = 0; i < 4; i++)
+					input_report_key(dev, interact_btn_hhfx[i + 8], (data[1] >> (i + 20)) & 1);
+
+				break;
+
+			case INTERACT_TYPE_PP8D:
+
+				for (i = 0; i < 2; i++)
+					input_report_abs(dev, interact_abs_pp8d[i],
+						((data[0] >> ((i << 1) + 20)) & 1)  - ((data[0] >> ((i << 1) + 21)) & 1));
+
+				for (i = 0; i < 8; i++)
+					input_report_key(dev, interact_btn_pp8d[i], (data[1] >> (i + 16)) & 1);
+
+				break;
+		}
+	}
+
+	input_sync(dev);
+}
+
+/*
+ * interact_open() is a callback from the input open routine.
+ */
+
+static int interact_open(struct input_dev *dev)
+{
+	struct interact *interact = input_get_drvdata(dev);
+
+	gameport_start_polling(interact->gameport);
+	return 0;
+}
+
+/*
+ * interact_close() is a callback from the input close routine.
+ */
+
+static void interact_close(struct input_dev *dev)
+{
+	struct interact *interact = input_get_drvdata(dev);
+
+	gameport_stop_polling(interact->gameport);
+}
+
+/*
+ * interact_connect() probes for InterAct joysticks.
+ */
+
+static int interact_connect(struct gameport *gameport, struct gameport_driver *drv)
+{
+	struct interact *interact;
+	struct input_dev *input_dev;
+	__u32 data[3];
+	int i, t;
+	int err;
+
+	interact = kzalloc_obj(*interact);
+	input_dev = input_allocate_device();
+	if (!interact || !input_dev) {
+		err = -ENOMEM;
+		goto fail1;
+	}
+
+	interact->gameport = gameport;
+	interact->dev = input_dev;
+
+	gameport_set_drvdata(gameport, interact);
+
+	err = gameport_open(gameport, drv, GAMEPORT_MODE_RAW);
+	if (err)
+		goto fail1;
+
+	i = interact_read_packet(gameport, INTERACT_MAX_LENGTH * 2, data);
+
+	if (i != 32 || (data[0] >> 24) != 0x0c || (data[1] >> 24) != 0x02) {
+		err = -ENODEV;
+		goto fail2;
+	}
+
+	for (i = 0; interact_type[i].length; i++)
+		if (interact_type[i].id == (data[2] >> 16))
+			break;
+
+	if (!interact_type[i].length) {
+		printk(KERN_WARNING "interact.c: Unknown joystick on %s. [len %d d0 %08x d1 %08x i2 %08x]\n",
+			gameport->phys, i, data[0], data[1], data[2]);
+		err = -ENODEV;
+		goto fail2;
+	}
+
+	gameport_set_poll_handler(gameport, interact_poll);
+	gameport_set_poll_interval(gameport, 20);
+
+	snprintf(interact->phys, sizeof(interact->phys), "%s/input0", gameport->phys);
+
+	interact->type = i;
+	interact->length = interact_type[i].length;
+
+	input_dev->name = interact_type[i].name;
+	input_dev->phys = interact->phys;
+	input_dev->id.bustype = BUS_GAMEPORT;
+	input_dev->id.vendor = GAMEPORT_ID_VENDOR_INTERACT;
+	input_dev->id.product = interact_type[i].id;
+	input_dev->id.version = 0x0100;
+	input_dev->dev.parent = &gameport->dev;
+
+	input_set_drvdata(input_dev, interact);
+
+	input_dev->open = interact_open;
+	input_dev->close = interact_close;
+
+	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
+
+	for (i = 0; (t = interact_type[interact->type].abs[i]) >= 0; i++) {
+		if (i < interact_type[interact->type].b8)
+			input_set_abs_params(input_dev, t, 0, 255, 0, 0);
+		else
+			input_set_abs_params(input_dev, t, -1, 1, 0, 0);
+	}
+
+	for (i = 0; (t = interact_type[interact->type].btn[i]) >= 0; i++)
+		__set_bit(t, input_dev->keybit);
+
+	err = input_register_device(interact->dev);
+	if (err)
+		goto fail2;
+
+	return 0;
+
+fail2:	gameport_close(gameport);
+fail1:  gameport_set_drvdata(gameport, NULL);
+	input_free_device(input_dev);
+	kfree(interact);
+	return err;
+}
+
+static void interact_disconnect(struct gameport *gameport)
+{
+	struct interact *interact = gameport_get_drvdata(gameport);
+
+	input_unregister_device(interact->dev);
+	gameport_close(gameport);
+	gameport_set_drvdata(gameport, NULL);
+	kfree(interact);
+}
+
+static struct gameport_driver interact_drv = {
+	.driver		= {
+		.name	= "interact",
+	},
+	.description	= DRIVER_DESC,
+	.connect	= interact_connect,
+	.disconnect	= interact_disconnect,
+};
+
+module_gameport_driver(interact_drv);