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, 154 insertions, 0 deletions

diff --git a/arch/mips/ralink/timer.c b/arch/mips/ralink/timer.c
new file mode 100644
index 000000000..06bc2c014
--- /dev/null
+++ b/arch/mips/ralink/timer.c
@@ -0,0 +1,154 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Ralink RT2880 timer
+ * Author: John Crispin
+ *
+ * Copyright (C) 2013 John Crispin <john@phrozen.org>
+*/
+
+#include <linux/bits.h>
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/platform_device.h>
+#include <linux/timer.h>
+#include <linux/types.h>
+
+#include <asm/mach-ralink/ralink_regs.h>
+
+#define TIMER_REG_TMRSTAT		0x00
+#define TIMER_REG_TMR0LOAD		0x10
+#define TIMER_REG_TMR0CTL		0x18
+
+#define TMRSTAT_TMR0INT			BIT(0)
+
+#define TMR0CTL_ENABLE			BIT(7)
+#define TMR0CTL_MODE_PERIODIC		BIT(4)
+#define TMR0CTL_PRESCALER		1
+#define TMR0CTL_PRESCALE_VAL		(0xf - TMR0CTL_PRESCALER)
+#define TMR0CTL_PRESCALE_DIV		(65536 / BIT(TMR0CTL_PRESCALER))
+
+struct rt_timer {
+	struct device	*dev;
+	void __iomem	*membase;
+	int		irq;
+	unsigned long	timer_freq;
+	unsigned long	timer_div;
+};
+
+static inline void rt_timer_w32(struct rt_timer *rt, u8 reg, u32 val)
+{
+	__raw_writel(val, rt->membase + reg);
+}
+
+static inline u32 rt_timer_r32(struct rt_timer *rt, u8 reg)
+{
+	return __raw_readl(rt->membase + reg);
+}
+
+static irqreturn_t rt_timer_irq(int irq, void *_rt)
+{
+	struct rt_timer *rt =  (struct rt_timer *) _rt;
+
+	rt_timer_w32(rt, TIMER_REG_TMR0LOAD, rt->timer_freq / rt->timer_div);
+	rt_timer_w32(rt, TIMER_REG_TMRSTAT, TMRSTAT_TMR0INT);
+
+	return IRQ_HANDLED;
+}
+
+
+static int rt_timer_request(struct rt_timer *rt)
+{
+	int err = request_irq(rt->irq, rt_timer_irq, 0,
+						dev_name(rt->dev), rt);
+	if (err) {
+		dev_err(rt->dev, "failed to request irq\n");
+	} else {
+		u32 t = TMR0CTL_MODE_PERIODIC | TMR0CTL_PRESCALE_VAL;
+		rt_timer_w32(rt, TIMER_REG_TMR0CTL, t);
+	}
+	return err;
+}
+
+static int rt_timer_config(struct rt_timer *rt, unsigned long divisor)
+{
+	if (rt->timer_freq < divisor)
+		rt->timer_div = rt->timer_freq;
+	else
+		rt->timer_div = divisor;
+
+	rt_timer_w32(rt, TIMER_REG_TMR0LOAD, rt->timer_freq / rt->timer_div);
+
+	return 0;
+}
+
+static int rt_timer_enable(struct rt_timer *rt)
+{
+	u32 t;
+
+	rt_timer_w32(rt, TIMER_REG_TMR0LOAD, rt->timer_freq / rt->timer_div);
+
+	t = rt_timer_r32(rt, TIMER_REG_TMR0CTL);
+	t |= TMR0CTL_ENABLE;
+	rt_timer_w32(rt, TIMER_REG_TMR0CTL, t);
+
+	return 0;
+}
+
+static int rt_timer_probe(struct platform_device *pdev)
+{
+	struct rt_timer *rt;
+	struct clk *clk;
+
+	rt = devm_kzalloc(&pdev->dev, sizeof(*rt), GFP_KERNEL);
+	if (!rt) {
+		dev_err(&pdev->dev, "failed to allocate memory\n");
+		return -ENOMEM;
+	}
+
+	rt->irq = platform_get_irq(pdev, 0);
+	if (rt->irq < 0)
+		return rt->irq;
+
+	rt->membase = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
+	if (IS_ERR(rt->membase))
+		return PTR_ERR(rt->membase);
+
+	clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(clk)) {
+		dev_err(&pdev->dev, "failed get clock rate\n");
+		return PTR_ERR(clk);
+	}
+
+	rt->timer_freq = clk_get_rate(clk) / TMR0CTL_PRESCALE_DIV;
+	if (!rt->timer_freq)
+		return -EINVAL;
+
+	rt->dev = &pdev->dev;
+	platform_set_drvdata(pdev, rt);
+
+	rt_timer_request(rt);
+	rt_timer_config(rt, 2);
+	rt_timer_enable(rt);
+
+	dev_info(&pdev->dev, "maximum frequency is %luHz\n", rt->timer_freq);
+
+	return 0;
+}
+
+static const struct of_device_id rt_timer_match[] = {
+	{ .compatible = "ralink,rt2880-timer" },
+	{},
+};
+
+static struct platform_driver rt_timer_driver = {
+	.probe = rt_timer_probe,
+	.driver = {
+		.name			= "rt-timer",
+		.of_match_table		= rt_timer_match,
+		.suppress_bind_attrs	= true,
+	},
+};
+builtin_platform_driver(rt_timer_driver);