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, 215 insertions, 0 deletions

diff --git a/drivers/clocksource/timer-gxp.c b/drivers/clocksource/timer-gxp.c
new file mode 100644
index 000000000..1becc9433
--- /dev/null
+++ b/drivers/clocksource/timer-gxp.c
@@ -0,0 +1,215 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2022 Hewlett-Packard Enterprise Development Company, L.P. */
+
+#include <linux/clk.h>
+#include <linux/clockchips.h>
+#include <linux/clocksource.h>
+#include <linux/interrupt.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/sched_clock.h>
+
+#define TIMER0_FREQ	1000000
+#define GXP_TIMER_CNT_OFS 0x00
+#define GXP_TIMESTAMP_OFS 0x08
+#define GXP_TIMER_CTRL_OFS 0x14
+
+/* TCS Stands for Timer Control/Status: these are masks to be used in */
+/* the Timer Count Registers */
+#define MASK_TCS_ENABLE	0x01
+#define MASK_TCS_PERIOD	0x02
+#define MASK_TCS_RELOAD	0x04
+#define MASK_TCS_TC	0x80
+
+struct gxp_timer {
+	void __iomem *counter;
+	void __iomem *control;
+	struct clock_event_device evt;
+};
+
+static struct gxp_timer *gxp_timer;
+
+static void __iomem *system_clock __ro_after_init;
+
+static inline struct gxp_timer *to_gxp_timer(struct clock_event_device *evt_dev)
+{
+	return container_of(evt_dev, struct gxp_timer, evt);
+}
+
+static u64 notrace gxp_sched_read(void)
+{
+	return readl_relaxed(system_clock);
+}
+
+static int gxp_time_set_next_event(unsigned long event, struct clock_event_device *evt_dev)
+{
+	struct gxp_timer *timer = to_gxp_timer(evt_dev);
+
+	/* Stop counting and disable interrupt before updating */
+	writeb_relaxed(MASK_TCS_TC, timer->control);
+	writel_relaxed(event, timer->counter);
+	writeb_relaxed(MASK_TCS_TC | MASK_TCS_ENABLE, timer->control);
+
+	return 0;
+}
+
+static irqreturn_t gxp_timer_interrupt(int irq, void *dev_id)
+{
+	struct gxp_timer *timer = (struct gxp_timer *)dev_id;
+
+	if (!(readb_relaxed(timer->control) & MASK_TCS_TC))
+		return IRQ_NONE;
+
+	writeb_relaxed(MASK_TCS_TC, timer->control);
+
+	timer->evt.event_handler(&timer->evt);
+
+	return IRQ_HANDLED;
+}
+
+static int __init gxp_timer_init(struct device_node *node)
+{
+	void __iomem *base;
+	struct clk *clk;
+	u32 freq;
+	int ret, irq;
+
+	gxp_timer = kzalloc_obj(*gxp_timer);
+	if (!gxp_timer) {
+		ret = -ENOMEM;
+		pr_err("Can't allocate gxp_timer");
+		return ret;
+	}
+
+	clk = of_clk_get(node, 0);
+	if (IS_ERR(clk)) {
+		ret = PTR_ERR(clk);
+		pr_err("%pOFn clock not found: %d\n", node, ret);
+		goto err_free;
+	}
+
+	ret = clk_prepare_enable(clk);
+	if (ret) {
+		pr_err("%pOFn clock enable failed: %d\n", node, ret);
+		goto err_clk_enable;
+	}
+
+	base = of_iomap(node, 0);
+	if (!base) {
+		ret = -ENXIO;
+		pr_err("Can't map timer base registers");
+		goto err_iomap;
+	}
+
+	/* Set the offsets to the clock register and timer registers */
+	gxp_timer->counter = base + GXP_TIMER_CNT_OFS;
+	gxp_timer->control = base + GXP_TIMER_CTRL_OFS;
+	system_clock = base + GXP_TIMESTAMP_OFS;
+
+	gxp_timer->evt.name = node->name;
+	gxp_timer->evt.rating = 300;
+	gxp_timer->evt.features = CLOCK_EVT_FEAT_ONESHOT;
+	gxp_timer->evt.set_next_event = gxp_time_set_next_event;
+	gxp_timer->evt.cpumask = cpumask_of(0);
+
+	irq = irq_of_parse_and_map(node, 0);
+	if (irq <= 0) {
+		ret = -EINVAL;
+		pr_err("GXP Timer Can't parse IRQ %d", irq);
+		goto err_exit;
+	}
+
+	freq = clk_get_rate(clk);
+
+	ret = clocksource_mmio_init(system_clock, node->name, freq,
+				    300, 32, clocksource_mmio_readl_up);
+	if (ret) {
+		pr_err("%pOFn init clocksource failed: %d", node, ret);
+		goto err_exit;
+	}
+
+	sched_clock_register(gxp_sched_read, 32, freq);
+
+	irq = irq_of_parse_and_map(node, 0);
+	if (irq <= 0) {
+		ret = -EINVAL;
+		pr_err("%pOFn Can't parse IRQ %d", node, irq);
+		goto err_exit;
+	}
+
+	clockevents_config_and_register(&gxp_timer->evt, TIMER0_FREQ,
+					0xf, 0xffffffff);
+
+	ret = request_irq(irq, gxp_timer_interrupt, IRQF_TIMER | IRQF_SHARED,
+			  node->name, gxp_timer);
+	if (ret) {
+		pr_err("%pOFn request_irq() failed: %d", node, ret);
+		goto err_exit;
+	}
+
+	pr_debug("gxp: system timer (irq = %d)\n", irq);
+	return 0;
+
+err_exit:
+	iounmap(base);
+err_iomap:
+	clk_disable_unprepare(clk);
+err_clk_enable:
+	clk_put(clk);
+err_free:
+	kfree(gxp_timer);
+	return ret;
+}
+
+/*
+ * This probe gets called after the timer is already up and running. This will create
+ * the watchdog device as a child since the registers are shared.
+ */
+
+static int gxp_timer_probe(struct platform_device *pdev)
+{
+	struct platform_device *gxp_watchdog_device;
+	struct device *dev = &pdev->dev;
+	int ret;
+
+	if (!gxp_timer) {
+		pr_err("Gxp Timer not initialized, cannot create watchdog");
+		return -ENOMEM;
+	}
+
+	gxp_watchdog_device = platform_device_alloc("gxp-wdt", -1);
+	if (!gxp_watchdog_device) {
+		pr_err("Timer failed to allocate gxp-wdt");
+		return -ENOMEM;
+	}
+
+	/* Pass the base address (counter) as platform data and nothing else */
+	gxp_watchdog_device->dev.platform_data = gxp_timer->counter;
+	gxp_watchdog_device->dev.parent = dev;
+
+	ret = platform_device_add(gxp_watchdog_device);
+	if (ret)
+		platform_device_put(gxp_watchdog_device);
+
+	return ret;
+}
+
+static const struct of_device_id gxp_timer_of_match[] = {
+	{ .compatible = "hpe,gxp-timer", },
+	{},
+};
+
+static struct platform_driver gxp_timer_driver = {
+	.probe  = gxp_timer_probe,
+	.driver = {
+		.name = "gxp-timer",
+		.of_match_table = gxp_timer_of_match,
+		.suppress_bind_attrs = true,
+	},
+};
+
+builtin_platform_driver(gxp_timer_driver);
+
+TIMER_OF_DECLARE(gxp, "hpe,gxp-timer", gxp_timer_init);