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, 222 insertions, 0 deletions

diff --git a/drivers/input/serio/parkbd.c b/drivers/input/serio/parkbd.c
new file mode 100644
index 000000000..09a24413d
--- /dev/null
+++ b/drivers/input/serio/parkbd.c
@@ -0,0 +1,222 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Parallel port to Keyboard port adapter driver for Linux
+ *
+ *  Copyright (c) 1999-2004 Vojtech Pavlik
+ */
+
+
+/*
+ * To connect an AT or XT keyboard to the parallel port, a fairly simple adapter
+ * can be made:
+ * 
+ *  Parallel port            Keyboard port
+ *
+ *     +5V --------------------- +5V (4)
+ *  
+ *                 ______
+ *     +5V -------|______|--.
+ *                          |
+ *     ACK (10) ------------|
+ *                          |--- KBD CLOCK (5)
+ *     STROBE (1) ---|<|----'
+ *     
+ *                 ______
+ *     +5V -------|______|--.
+ *                          |
+ *     BUSY (11) -----------|
+ *                          |--- KBD DATA (1)
+ *     AUTOFD (14) --|<|----'
+ *
+ *     GND (18-25) ------------- GND (3)
+ *     
+ * The diodes can be fairly any type, and the resistors should be somewhere
+ * around 5 kOhm, but the adapter will likely work without the resistors,
+ * too.
+ *
+ * The +5V source can be taken either from USB, from mouse or keyboard ports,
+ * or from a joystick port. Unfortunately, the parallel port of a PC doesn't
+ * have a +5V pin, and feeding the keyboard from signal pins is out of question
+ * with 300 mA power reqirement of a typical AT keyboard.
+ */
+
+#include <linux/module.h>
+#include <linux/parport.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/serio.h>
+
+MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
+MODULE_DESCRIPTION("Parallel port to Keyboard port adapter driver");
+MODULE_LICENSE("GPL");
+
+static unsigned int parkbd_pp_no;
+module_param_named(port, parkbd_pp_no, int, 0);
+MODULE_PARM_DESC(port, "Parallel port the adapter is connected to (default is 0)");
+
+static unsigned int parkbd_mode = SERIO_8042;
+module_param_named(mode, parkbd_mode, uint, 0);
+MODULE_PARM_DESC(mode, "Mode of operation: XT = 0/AT = 1 (default)");
+
+#define PARKBD_CLOCK	0x01	/* Strobe & Ack */
+#define PARKBD_DATA	0x02	/* AutoFd & Busy */
+
+static int parkbd_buffer;
+static int parkbd_counter;
+static unsigned long parkbd_last;
+static int parkbd_writing;
+static unsigned long parkbd_start;
+
+static struct pardevice *parkbd_dev;
+static struct serio *parkbd_port;
+
+static int parkbd_readlines(void)
+{
+	return (parport_read_status(parkbd_dev->port) >> 6) ^ 2;
+}
+
+static void parkbd_writelines(int data)
+{
+	parport_write_control(parkbd_dev->port, (~data & 3) | 0x10);
+}
+
+static int parkbd_write(struct serio *port, unsigned char c)
+{
+	unsigned char p;
+
+	if (!parkbd_mode) return -1;
+
+        p = c ^ (c >> 4);
+	p = p ^ (p >> 2);
+	p = p ^ (p >> 1);
+
+	parkbd_counter = 0;
+	parkbd_writing = 1;
+	parkbd_buffer = c | (((int) (~p & 1)) << 8) | 0x600;
+
+	parkbd_writelines(2);
+
+	return 0;
+}
+
+static void parkbd_interrupt(void *dev_id)
+{
+
+	if (parkbd_writing) {
+
+		if (parkbd_counter && ((parkbd_counter == 11) || time_after(jiffies, parkbd_last + HZ/100))) {
+			parkbd_counter = 0;
+			parkbd_buffer = 0;
+			parkbd_writing = 0;
+			parkbd_writelines(3);
+			return;
+		}
+
+		parkbd_writelines(((parkbd_buffer >> parkbd_counter++) & 1) | 2);
+
+		if (parkbd_counter == 11) {
+			parkbd_counter = 0;
+			parkbd_buffer = 0;
+			parkbd_writing = 0;
+			parkbd_writelines(3);
+		}
+
+	} else {
+
+		if ((parkbd_counter == parkbd_mode + 10) || time_after(jiffies, parkbd_last + HZ/100)) {
+			parkbd_counter = 0;
+			parkbd_buffer = 0;
+		}
+
+		parkbd_buffer |= (parkbd_readlines() >> 1) << parkbd_counter++;
+
+		if (parkbd_counter == parkbd_mode + 10)
+			serio_interrupt(parkbd_port, (parkbd_buffer >> (2 - parkbd_mode)) & 0xff, 0);
+	}
+
+	parkbd_last = jiffies;
+}
+
+static int parkbd_getport(struct parport *pp)
+{
+	struct pardev_cb parkbd_parport_cb;
+
+	memset(&parkbd_parport_cb, 0, sizeof(parkbd_parport_cb));
+	parkbd_parport_cb.irq_func = parkbd_interrupt;
+	parkbd_parport_cb.flags = PARPORT_FLAG_EXCL;
+
+	parkbd_dev = parport_register_dev_model(pp, "parkbd",
+						&parkbd_parport_cb, 0);
+
+	if (!parkbd_dev)
+		return -ENODEV;
+
+	if (parport_claim(parkbd_dev)) {
+		parport_unregister_device(parkbd_dev);
+		return -EBUSY;
+	}
+
+	parkbd_start = jiffies;
+
+	return 0;
+}
+
+static struct serio *parkbd_allocate_serio(void)
+{
+	struct serio *serio;
+
+	serio = kzalloc_obj(*serio);
+	if (serio) {
+		serio->id.type = parkbd_mode;
+		serio->write = parkbd_write;
+		strscpy(serio->name, "PARKBD AT/XT keyboard adapter", sizeof(serio->name));
+		snprintf(serio->phys, sizeof(serio->phys), "%s/serio0", parkbd_dev->port->name);
+	}
+
+	return serio;
+}
+
+static void parkbd_attach(struct parport *pp)
+{
+	if (pp->number != parkbd_pp_no) {
+		pr_debug("Not using parport%d.\n", pp->number);
+		return;
+	}
+
+	if (parkbd_getport(pp))
+		return;
+
+	parkbd_port = parkbd_allocate_serio();
+	if (!parkbd_port) {
+		parport_release(parkbd_dev);
+		parport_unregister_device(parkbd_dev);
+		return;
+	}
+
+	parkbd_writelines(3);
+
+	serio_register_port(parkbd_port);
+
+	printk(KERN_INFO "serio: PARKBD %s adapter on %s\n",
+                        parkbd_mode ? "AT" : "XT", parkbd_dev->port->name);
+
+	return;
+}
+
+static void parkbd_detach(struct parport *port)
+{
+	if (!parkbd_port || port->number != parkbd_pp_no)
+		return;
+
+	parport_release(parkbd_dev);
+	serio_unregister_port(parkbd_port);
+	parport_unregister_device(parkbd_dev);
+	parkbd_port = NULL;
+}
+
+static struct parport_driver parkbd_parport_driver = {
+	.name = "parkbd",
+	.match_port = parkbd_attach,
+	.detach = parkbd_detach,
+};
+module_parport_driver(parkbd_parport_driver);