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, 167 insertions, 0 deletions

diff --git a/drivers/hid/hid-a4tech.c b/drivers/hid/hid-a4tech.c
new file mode 100644
index 000000000..54bfaf611
--- /dev/null
+++ b/drivers/hid/hid-a4tech.c
@@ -0,0 +1,167 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  HID driver for some a4tech "special" devices
+ *
+ *  Copyright (c) 1999 Andreas Gal
+ *  Copyright (c) 2000-2005 Vojtech Pavlik <vojtech@suse.cz>
+ *  Copyright (c) 2005 Michael Haboustak <mike-@cinci.rr.com> for Concept2, Inc
+ *  Copyright (c) 2006-2007 Jiri Kosina
+ *  Copyright (c) 2008 Jiri Slaby
+ */
+
+/*
+ */
+
+#include <linux/device.h>
+#include <linux/input.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+#include "hid-ids.h"
+
+#define A4_2WHEEL_MOUSE_HACK_7	0x01
+#define A4_2WHEEL_MOUSE_HACK_B8	0x02
+
+#define A4_WHEEL_ORIENTATION	(HID_UP_GENDESK | 0x000000b8)
+
+struct a4tech_sc {
+	unsigned long quirks;
+	unsigned int hw_wheel;
+	__s32 delayed_value;
+};
+
+static int a4_input_mapping(struct hid_device *hdev, struct hid_input *hi,
+			    struct hid_field *field, struct hid_usage *usage,
+			    unsigned long **bit, int *max)
+{
+	struct a4tech_sc *a4 = hid_get_drvdata(hdev);
+
+	if (a4->quirks & A4_2WHEEL_MOUSE_HACK_B8 &&
+	    usage->hid == A4_WHEEL_ORIENTATION) {
+		/*
+		 * We do not want to have this usage mapped to anything as it's
+		 * nonstandard and doesn't really behave like an HID report.
+		 * It's only selecting the orientation (vertical/horizontal) of
+		 * the previous mouse wheel report. The input_events will be
+		 * generated once both reports are recorded in a4_event().
+		 */
+		return -1;
+	}
+
+	return 0;
+
+}
+
+static int a4_input_mapped(struct hid_device *hdev, struct hid_input *hi,
+		struct hid_field *field, struct hid_usage *usage,
+		unsigned long **bit, int *max)
+{
+	struct a4tech_sc *a4 = hid_get_drvdata(hdev);
+
+	if (usage->type == EV_REL && usage->code == REL_WHEEL_HI_RES) {
+		set_bit(REL_HWHEEL, *bit);
+		set_bit(REL_HWHEEL_HI_RES, *bit);
+	}
+
+	if ((a4->quirks & A4_2WHEEL_MOUSE_HACK_7) && usage->hid == 0x00090007)
+		return -1;
+
+	return 0;
+}
+
+static int a4_event(struct hid_device *hdev, struct hid_field *field,
+		struct hid_usage *usage, __s32 value)
+{
+	struct a4tech_sc *a4 = hid_get_drvdata(hdev);
+	struct input_dev *input;
+
+	if (!(hdev->claimed & HID_CLAIMED_INPUT) || !field->hidinput)
+		return 0;
+
+	input = field->hidinput->input;
+
+	if (a4->quirks & A4_2WHEEL_MOUSE_HACK_B8) {
+		if (usage->type == EV_REL && usage->code == REL_WHEEL_HI_RES) {
+			a4->delayed_value = value;
+			return 1;
+		}
+
+		if (usage->hid == A4_WHEEL_ORIENTATION) {
+			input_event(input, EV_REL, value ? REL_HWHEEL :
+					REL_WHEEL, a4->delayed_value);
+			input_event(input, EV_REL, value ? REL_HWHEEL_HI_RES :
+					REL_WHEEL_HI_RES, a4->delayed_value * 120);
+			return 1;
+		}
+	}
+
+	if ((a4->quirks & A4_2WHEEL_MOUSE_HACK_7) && usage->hid == 0x00090007) {
+		a4->hw_wheel = !!value;
+		return 1;
+	}
+
+	if (usage->code == REL_WHEEL_HI_RES && a4->hw_wheel) {
+		input_event(input, usage->type, REL_HWHEEL, value);
+		input_event(input, usage->type, REL_HWHEEL_HI_RES, value * 120);
+		return 1;
+	}
+
+	return 0;
+}
+
+static int a4_probe(struct hid_device *hdev, const struct hid_device_id *id)
+{
+	struct a4tech_sc *a4;
+	int ret;
+
+	a4 = devm_kzalloc(&hdev->dev, sizeof(*a4), GFP_KERNEL);
+	if (a4 == NULL) {
+		hid_err(hdev, "can't alloc device descriptor\n");
+		return -ENOMEM;
+	}
+
+	a4->quirks = id->driver_data;
+
+	hid_set_drvdata(hdev, a4);
+
+	ret = hid_parse(hdev);
+	if (ret) {
+		hid_err(hdev, "parse failed\n");
+		return ret;
+	}
+
+	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+	if (ret) {
+		hid_err(hdev, "hw start failed\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct hid_device_id a4_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_A4TECH, USB_DEVICE_ID_A4TECH_WCP32PU),
+		.driver_data = A4_2WHEEL_MOUSE_HACK_7 },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_A4TECH, USB_DEVICE_ID_A4TECH_X5_005D),
+		.driver_data = A4_2WHEEL_MOUSE_HACK_B8 },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_A4TECH, USB_DEVICE_ID_A4TECH_RP_649),
+		.driver_data = A4_2WHEEL_MOUSE_HACK_B8 },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_A4TECH, USB_DEVICE_ID_A4TECH_NB_95),
+		.driver_data = A4_2WHEEL_MOUSE_HACK_B8 },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, a4_devices);
+
+static struct hid_driver a4_driver = {
+	.name = "a4tech",
+	.id_table = a4_devices,
+	.input_mapping = a4_input_mapping,
+	.input_mapped = a4_input_mapped,
+	.event = a4_event,
+	.probe = a4_probe,
+};
+module_hid_driver(a4_driver);
+
+MODULE_DESCRIPTION("HID driver for some a4tech \"special\" devices");
+MODULE_LICENSE("GPL");