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, 200 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/mtouch.c b/drivers/input/touchscreen/mtouch.c
new file mode 100644
index 000000000..cc2d206d2
--- /dev/null
+++ b/drivers/input/touchscreen/mtouch.c
@@ -0,0 +1,200 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * MicroTouch (3M) serial touchscreen driver
+ *
+ * Copyright (c) 2004 Vojtech Pavlik
+ */
+
+
+/*
+ * 2005/02/19 Dan Streetman <ddstreet@ieee.org>
+ *   Copied elo.c and edited for MicroTouch protocol
+ */
+
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/input.h>
+#include <linux/serio.h>
+
+#define DRIVER_DESC	"MicroTouch serial touchscreen driver"
+
+MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
+
+/*
+ * Definitions & global arrays.
+ */
+
+#define MTOUCH_FORMAT_TABLET_STATUS_BIT 0x80
+#define MTOUCH_FORMAT_TABLET_TOUCH_BIT 0x40
+#define MTOUCH_FORMAT_TABLET_LENGTH 5
+#define MTOUCH_RESPONSE_BEGIN_BYTE 0x01
+#define MTOUCH_RESPONSE_END_BYTE 0x0d
+
+/* todo: check specs for max length of all responses */
+#define MTOUCH_MAX_LENGTH 16
+
+#define MTOUCH_MIN_XC 0
+#define MTOUCH_MAX_XC 0x3fff
+#define MTOUCH_MIN_YC 0
+#define MTOUCH_MAX_YC 0x3fff
+
+#define MTOUCH_GET_XC(data) (((data[2])<<7) | data[1])
+#define MTOUCH_GET_YC(data) (((data[4])<<7) | data[3])
+#define MTOUCH_GET_TOUCHED(data) (MTOUCH_FORMAT_TABLET_TOUCH_BIT & data[0])
+
+/*
+ * Per-touchscreen data.
+ */
+
+struct mtouch {
+	struct input_dev *dev;
+	struct serio *serio;
+	int idx;
+	unsigned char data[MTOUCH_MAX_LENGTH];
+	char phys[32];
+};
+
+static void mtouch_process_format_tablet(struct mtouch *mtouch)
+{
+	struct input_dev *dev = mtouch->dev;
+
+	if (MTOUCH_FORMAT_TABLET_LENGTH == ++mtouch->idx) {
+		input_report_abs(dev, ABS_X, MTOUCH_GET_XC(mtouch->data));
+		input_report_abs(dev, ABS_Y, MTOUCH_MAX_YC - MTOUCH_GET_YC(mtouch->data));
+		input_report_key(dev, BTN_TOUCH, MTOUCH_GET_TOUCHED(mtouch->data));
+		input_sync(dev);
+
+		mtouch->idx = 0;
+	}
+}
+
+static void mtouch_process_response(struct mtouch *mtouch)
+{
+	if (MTOUCH_RESPONSE_END_BYTE == mtouch->data[mtouch->idx++]) {
+		/* FIXME - process response */
+		mtouch->idx = 0;
+	} else if (MTOUCH_MAX_LENGTH == mtouch->idx) {
+		printk(KERN_ERR "mtouch.c: too many response bytes\n");
+		mtouch->idx = 0;
+	}
+}
+
+static irqreturn_t mtouch_interrupt(struct serio *serio,
+		unsigned char data, unsigned int flags)
+{
+	struct mtouch *mtouch = serio_get_drvdata(serio);
+
+	mtouch->data[mtouch->idx] = data;
+
+	if (MTOUCH_FORMAT_TABLET_STATUS_BIT & mtouch->data[0])
+		mtouch_process_format_tablet(mtouch);
+	else if (MTOUCH_RESPONSE_BEGIN_BYTE == mtouch->data[0])
+		mtouch_process_response(mtouch);
+	else
+		printk(KERN_DEBUG "mtouch.c: unknown/unsynchronized data from device, byte %x\n",mtouch->data[0]);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * mtouch_disconnect() is the opposite of mtouch_connect()
+ */
+
+static void mtouch_disconnect(struct serio *serio)
+{
+	struct mtouch *mtouch = serio_get_drvdata(serio);
+
+	input_get_device(mtouch->dev);
+	input_unregister_device(mtouch->dev);
+	serio_close(serio);
+	serio_set_drvdata(serio, NULL);
+	input_put_device(mtouch->dev);
+	kfree(mtouch);
+}
+
+/*
+ * mtouch_connect() is the routine that is called when someone adds a
+ * new serio device that supports MicroTouch (Format Tablet) protocol and registers it as
+ * an input device.
+ */
+
+static int mtouch_connect(struct serio *serio, struct serio_driver *drv)
+{
+	struct mtouch *mtouch;
+	struct input_dev *input_dev;
+	int err;
+
+	mtouch = kzalloc_obj(*mtouch);
+	input_dev = input_allocate_device();
+	if (!mtouch || !input_dev) {
+		err = -ENOMEM;
+		goto fail1;
+	}
+
+	mtouch->serio = serio;
+	mtouch->dev = input_dev;
+	scnprintf(mtouch->phys, sizeof(mtouch->phys), "%s/input0", serio->phys);
+
+	input_dev->name = "MicroTouch Serial TouchScreen";
+	input_dev->phys = mtouch->phys;
+	input_dev->id.bustype = BUS_RS232;
+	input_dev->id.vendor = SERIO_MICROTOUCH;
+	input_dev->id.product = 0;
+	input_dev->id.version = 0x0100;
+	input_dev->dev.parent = &serio->dev;
+	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
+	input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
+	input_set_abs_params(mtouch->dev, ABS_X, MTOUCH_MIN_XC, MTOUCH_MAX_XC, 0, 0);
+	input_set_abs_params(mtouch->dev, ABS_Y, MTOUCH_MIN_YC, MTOUCH_MAX_YC, 0, 0);
+
+	serio_set_drvdata(serio, mtouch);
+
+	err = serio_open(serio, drv);
+	if (err)
+		goto fail2;
+
+	err = input_register_device(mtouch->dev);
+	if (err)
+		goto fail3;
+
+	return 0;
+
+ fail3:	serio_close(serio);
+ fail2:	serio_set_drvdata(serio, NULL);
+ fail1:	input_free_device(input_dev);
+	kfree(mtouch);
+	return err;
+}
+
+/*
+ * The serio driver structure.
+ */
+
+static const struct serio_device_id mtouch_serio_ids[] = {
+	{
+		.type	= SERIO_RS232,
+		.proto	= SERIO_MICROTOUCH,
+		.id	= SERIO_ANY,
+		.extra	= SERIO_ANY,
+	},
+	{ 0 }
+};
+
+MODULE_DEVICE_TABLE(serio, mtouch_serio_ids);
+
+static struct serio_driver mtouch_drv = {
+	.driver		= {
+		.name	= "mtouch",
+	},
+	.description	= DRIVER_DESC,
+	.id_table	= mtouch_serio_ids,
+	.interrupt	= mtouch_interrupt,
+	.connect	= mtouch_connect,
+	.disconnect	= mtouch_disconnect,
+};
+
+module_serio_driver(mtouch_drv);