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, 256 insertions, 0 deletions

diff --git a/drivers/thunderbolt/cap.c b/drivers/thunderbolt/cap.c
new file mode 100644
index 000000000..4ab22d529
--- /dev/null
+++ b/drivers/thunderbolt/cap.c
@@ -0,0 +1,256 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Thunderbolt driver - capabilities lookup
+ *
+ * Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
+ * Copyright (C) 2018, Intel Corporation
+ */
+
+#include <linux/slab.h>
+#include <linux/errno.h>
+
+#include "tb.h"
+
+#define CAP_OFFSET_MAX		0xff
+#define VSE_CAP_OFFSET_MAX	0xffff
+#define TMU_ACCESS_EN		BIT(20)
+
+static int tb_port_enable_tmu(struct tb_port *port, bool enable)
+{
+	struct tb_switch *sw = port->sw;
+	u32 value, offset;
+	int ret;
+
+	/*
+	 * Legacy devices need to have TMU access enabled before port
+	 * space can be fully accessed.
+	 */
+	if (tb_switch_is_light_ridge(sw))
+		offset = 0x26;
+	else if (tb_switch_is_eagle_ridge(sw))
+		offset = 0x2a;
+	else
+		return 0;
+
+	ret = tb_sw_read(sw, &value, TB_CFG_SWITCH, offset, 1);
+	if (ret)
+		return ret;
+
+	if (enable)
+		value |= TMU_ACCESS_EN;
+	else
+		value &= ~TMU_ACCESS_EN;
+
+	return tb_sw_write(sw, &value, TB_CFG_SWITCH, offset, 1);
+}
+
+static void tb_port_dummy_read(struct tb_port *port)
+{
+	/*
+	 * When reading from next capability pointer location in port
+	 * config space the read data is not cleared on LR. To avoid
+	 * reading stale data on next read perform one dummy read after
+	 * port capabilities are walked.
+	 */
+	if (tb_switch_is_light_ridge(port->sw)) {
+		u32 dummy;
+
+		tb_port_read(port, &dummy, TB_CFG_PORT, 0, 1);
+	}
+}
+
+/**
+ * tb_port_next_cap() - Return next capability in the linked list
+ * @port: Port to find the capability for
+ * @offset: Previous capability offset (%0 for start)
+ *
+ * Finds dword offset of the next capability in port config space
+ * capability list. When passed %0 in @offset parameter, first entry
+ * will be returned, if it exists.
+ *
+ * Return:
+ * * Double word offset of the first or next capability - On success.
+ * * %0 - If no next capability is found.
+ * * Negative errno - Another error occurred.
+ */
+int tb_port_next_cap(struct tb_port *port, unsigned int offset)
+{
+	struct tb_cap_any header;
+	int ret;
+
+	if (!offset)
+		return port->config.first_cap_offset;
+
+	ret = tb_port_read(port, &header, TB_CFG_PORT, offset, 1);
+	if (ret)
+		return ret;
+
+	return header.basic.next;
+}
+
+static int __tb_port_find_cap(struct tb_port *port, enum tb_port_cap cap)
+{
+	int offset = 0;
+
+	do {
+		struct tb_cap_any header;
+		int ret;
+
+		offset = tb_port_next_cap(port, offset);
+		if (offset < 0)
+			return offset;
+
+		ret = tb_port_read(port, &header, TB_CFG_PORT, offset, 1);
+		if (ret)
+			return ret;
+
+		if (header.basic.cap == cap)
+			return offset;
+	} while (offset > 0);
+
+	return -ENOENT;
+}
+
+/**
+ * tb_port_find_cap() - Find port capability
+ * @port: Port to find the capability for
+ * @cap: Capability to look
+ *
+ * Return:
+ * * Offset to the start of capability - On success.
+ * * %-ENOENT - If no such capability was found.
+ * * Negative errno - Another error occurred.
+ */
+int tb_port_find_cap(struct tb_port *port, enum tb_port_cap cap)
+{
+	int ret;
+
+	ret = tb_port_enable_tmu(port, true);
+	if (ret)
+		return ret;
+
+	ret = __tb_port_find_cap(port, cap);
+
+	tb_port_dummy_read(port);
+	tb_port_enable_tmu(port, false);
+
+	return ret;
+}
+
+/**
+ * tb_switch_next_cap() - Return next capability in the linked list
+ * @sw: Switch to find the capability for
+ * @offset: Previous capability offset (%0 for start)
+ *
+ * Finds dword offset of the next capability in port config space
+ * capability list. When passed %0 in @offset parameter, first entry
+ * will be returned, if it exists.
+ *
+ * Return:
+ * * Double word offset of the first or next capability - On success.
+ * * %0 - If no next capability is found.
+ * * Negative errno - Another error occurred.
+ */
+int tb_switch_next_cap(struct tb_switch *sw, unsigned int offset)
+{
+	struct tb_cap_any header;
+	int ret;
+
+	if (!offset)
+		return sw->config.first_cap_offset;
+
+	ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 2);
+	if (ret)
+		return ret;
+
+	switch (header.basic.cap) {
+	case TB_SWITCH_CAP_TMU:
+		ret = header.basic.next;
+		break;
+
+	case TB_SWITCH_CAP_VSE:
+		if (!header.extended_short.length)
+			ret = header.extended_long.next;
+		else
+			ret = header.extended_short.next;
+		break;
+
+	default:
+		tb_sw_dbg(sw, "unknown capability %#x at %#x\n",
+			  header.basic.cap, offset);
+		ret = -EINVAL;
+		break;
+	}
+
+	return ret >= VSE_CAP_OFFSET_MAX ? 0 : ret;
+}
+
+/**
+ * tb_switch_find_cap() - Find switch capability
+ * @sw: Switch to find the capability for
+ * @cap: Capability to look
+ *
+ * Return:
+ * * Offset to the start of capability - On success.
+ * * %-ENOENT - If no such capability was found.
+ * * Negative errno - Another error occurred.
+ */
+int tb_switch_find_cap(struct tb_switch *sw, enum tb_switch_cap cap)
+{
+	int offset = 0;
+
+	do {
+		struct tb_cap_any header;
+		int ret;
+
+		offset = tb_switch_next_cap(sw, offset);
+		if (offset < 0)
+			return offset;
+
+		ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 1);
+		if (ret)
+			return ret;
+
+		if (header.basic.cap == cap)
+			return offset;
+	} while (offset);
+
+	return -ENOENT;
+}
+
+/**
+ * tb_switch_find_vse_cap() - Find switch vendor specific capability
+ * @sw: Switch to find the capability for
+ * @vsec: Vendor specific capability to look
+ *
+ * This function enumerates vendor specific capabilities (VSEC) of a
+ * switch and returns offset when capability matching @vsec is found.
+ *
+ * Return:
+ * * Offset of capability - On success.
+ * * %-ENOENT - If capability was not found.
+ * * Negative errno - Another error occurred.
+ */
+int tb_switch_find_vse_cap(struct tb_switch *sw, enum tb_switch_vse_cap vsec)
+{
+	int offset = 0;
+
+	do {
+		struct tb_cap_any header;
+		int ret;
+
+		offset = tb_switch_next_cap(sw, offset);
+		if (offset < 0)
+			return offset;
+
+		ret = tb_sw_read(sw, &header, TB_CFG_SWITCH, offset, 1);
+		if (ret)
+			return ret;
+
+		if (header.extended_short.cap == TB_SWITCH_CAP_VSE &&
+		    header.extended_short.vsec_id == vsec)
+			return offset;
+	} while (offset);
+
+	return -ENOENT;
+}