Merge branches 'expcb.2026.07.24a', 'misc.2026.07.30a', 'rcu-tasks.2026.07.30a', 'srcu.2026.08.11a' and 'torture.2026.08.14a' into HEADgrafted

Changes:

Make expedited grace periods expedite normal RCU callbacks

Miscellaneous fixes:
 * Improve diagnostic output with character task states.
 * Mark accesses to inform KCSAN of concurrency design.
 * Move from kmalloc() to kmalloc_obj().
 * Documentation updates.
 * Improve handling of RCU deferred quiescent states.
 * Clean up unused function arguments and structure fields.
 * Reduce show_rcu_gp_kthreads() stack space.

Tasks RCU updates:
 * Clean up after SRCU re-implementation of Tasks Trace RCU.
 * Mark accesses to inform KCSAN of concurrency design.
 * Add ->lazy_timer status to diagnostic output.
 * Remove an unnecessary memory barrier.
 * Fix a data race, courtesy of KCSAN.
 * Documentation updates.
 * Convert cond_resched_tasks_rcu_qs() from macro to static inline
   function.

SRCU updates:
 * Add Rust helpers for SRCU.
 * Avoid losing queued work at cleanup_srcu_struct() time.

Torture-test updates:
 * Preparation work for immediate RCU priority deboosting.
 * Test RCU readers from real interrupt handlers (as opposed to softirq).
 * Simplify code through use of cpumask_next_wrap().
 * Improve diagnostic output with character task states.
 * Add rcutorture.nwriters parameter to allow lightweight stall testing,
   and rcutorture.stall_only to make doing so easier.
 * Test an RCU Tasks Trace grace period implying an RCU grace period.
 * Make RCU Tasks Trace torturing track reader batches.
 * Fix a data race, courtesy of KCSAN.
 * Plug a shuffle_tmp_mask memory leak on kthread spawn failure.

1 files changed, 205 insertions, 0 deletions

diff --git a/drivers/input/joystick/magellan.c b/drivers/input/joystick/magellan.c
new file mode 100644
index 000000000..201a049c8
--- /dev/null
+++ b/drivers/input/joystick/magellan.c
@@ -0,0 +1,205 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Copyright (c) 1999-2001 Vojtech Pavlik
+ */
+
+/*
+ * Magellan and Space Mouse 6dof controller driver for Linux
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/input.h>
+#include <linux/serio.h>
+
+#define DRIVER_DESC	"Magellan and SpaceMouse 6dof controller driver"
+
+MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
+
+/*
+ * Definitions & global arrays.
+ */
+
+#define	MAGELLAN_MAX_LENGTH	32
+
+static int magellan_buttons[] = { BTN_0, BTN_1, BTN_2, BTN_3, BTN_4, BTN_5, BTN_6, BTN_7, BTN_8 };
+static int magellan_axes[] = { ABS_X, ABS_Y, ABS_Z, ABS_RX, ABS_RY, ABS_RZ };
+
+/*
+ * Per-Magellan data.
+ */
+
+struct magellan {
+	struct input_dev *dev;
+	int idx;
+	unsigned char data[MAGELLAN_MAX_LENGTH];
+	char phys[32];
+};
+
+/*
+ * magellan_crunch_nibbles() verifies that the bytes sent from the Magellan
+ * have correct upper nibbles for the lower ones, if not, the packet will
+ * be thrown away. It also strips these upper halves to simplify further
+ * processing.
+ */
+
+static int magellan_crunch_nibbles(unsigned char *data, int count)
+{
+	static const unsigned char nibbles[16] __nonstring = "0AB3D56GH9:K<MN?";
+
+	do {
+		if (data[count] == nibbles[data[count] & 0xf])
+			data[count] = data[count] & 0xf;
+		else
+			return -1;
+	} while (--count);
+
+	return 0;
+}
+
+static void magellan_process_packet(struct magellan* magellan)
+{
+	struct input_dev *dev = magellan->dev;
+	unsigned char *data = magellan->data;
+	int i, t;
+
+	if (!magellan->idx) return;
+
+	switch (magellan->data[0]) {
+
+		case 'd':				/* Axis data */
+			if (magellan->idx != 25) return;
+			if (magellan_crunch_nibbles(data, 24)) return;
+			for (i = 0; i < 6; i++)
+				input_report_abs(dev, magellan_axes[i],
+					(data[(i << 2) + 1] << 12 | data[(i << 2) + 2] << 8 |
+					 data[(i << 2) + 3] <<  4 | data[(i << 2) + 4]) - 32768);
+			break;
+
+		case 'k':				/* Button data */
+			if (magellan->idx != 4) return;
+			if (magellan_crunch_nibbles(data, 3)) return;
+			t = (data[1] << 1) | (data[2] << 5) | data[3];
+			for (i = 0; i < 9; i++) input_report_key(dev, magellan_buttons[i], (t >> i) & 1);
+			break;
+	}
+
+	input_sync(dev);
+}
+
+static irqreturn_t magellan_interrupt(struct serio *serio,
+		unsigned char data, unsigned int flags)
+{
+	struct magellan* magellan = serio_get_drvdata(serio);
+
+	if (data == '\r') {
+		magellan_process_packet(magellan);
+		magellan->idx = 0;
+	} else {
+		if (magellan->idx < MAGELLAN_MAX_LENGTH)
+			magellan->data[magellan->idx++] = data;
+	}
+	return IRQ_HANDLED;
+}
+
+/*
+ * magellan_disconnect() is the opposite of magellan_connect()
+ */
+
+static void magellan_disconnect(struct serio *serio)
+{
+	struct magellan* magellan = serio_get_drvdata(serio);
+
+	serio_close(serio);
+	serio_set_drvdata(serio, NULL);
+	input_unregister_device(magellan->dev);
+	kfree(magellan);
+}
+
+/*
+ * magellan_connect() is the routine that is called when someone adds a
+ * new serio device that supports Magellan protocol and registers it as
+ * an input device.
+ */
+
+static int magellan_connect(struct serio *serio, struct serio_driver *drv)
+{
+	struct magellan *magellan;
+	struct input_dev *input_dev;
+	int err = -ENOMEM;
+	int i;
+
+	magellan = kzalloc_obj(*magellan);
+	input_dev = input_allocate_device();
+	if (!magellan || !input_dev)
+		goto fail1;
+
+	magellan->dev = input_dev;
+	snprintf(magellan->phys, sizeof(magellan->phys), "%s/input0", serio->phys);
+
+	input_dev->name = "LogiCad3D Magellan / SpaceMouse";
+	input_dev->phys = magellan->phys;
+	input_dev->id.bustype = BUS_RS232;
+	input_dev->id.vendor = SERIO_MAGELLAN;
+	input_dev->id.product = 0x0001;
+	input_dev->id.version = 0x0100;
+	input_dev->dev.parent = &serio->dev;
+
+	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
+
+	for (i = 0; i < 9; i++)
+		set_bit(magellan_buttons[i], input_dev->keybit);
+
+	for (i = 0; i < 6; i++)
+		input_set_abs_params(input_dev, magellan_axes[i], -360, 360, 0, 0);
+
+	serio_set_drvdata(serio, magellan);
+
+	err = serio_open(serio, drv);
+	if (err)
+		goto fail2;
+
+	err = input_register_device(magellan->dev);
+	if (err)
+		goto fail3;
+
+	return 0;
+
+ fail3:	serio_close(serio);
+ fail2:	serio_set_drvdata(serio, NULL);
+ fail1:	input_free_device(input_dev);
+	kfree(magellan);
+	return err;
+}
+
+/*
+ * The serio driver structure.
+ */
+
+static const struct serio_device_id magellan_serio_ids[] = {
+	{
+		.type	= SERIO_RS232,
+		.proto	= SERIO_MAGELLAN,
+		.id	= SERIO_ANY,
+		.extra	= SERIO_ANY,
+	},
+	{ 0 }
+};
+
+MODULE_DEVICE_TABLE(serio, magellan_serio_ids);
+
+static struct serio_driver magellan_drv = {
+	.driver		= {
+		.name	= "magellan",
+	},
+	.description	= DRIVER_DESC,
+	.id_table	= magellan_serio_ids,
+	.interrupt	= magellan_interrupt,
+	.connect	= magellan_connect,
+	.disconnect	= magellan_disconnect,
+};
+
+module_serio_driver(magellan_drv);