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, 175 insertions, 0 deletions

diff --git a/lib/oid_registry.c b/lib/oid_registry.c
new file mode 100644
index 000000000..9b757a117
--- /dev/null
+++ b/lib/oid_registry.c
@@ -0,0 +1,175 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* ASN.1 Object identifier (OID) registry
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/module.h>
+#include <linux/export.h>
+#include <linux/oid_registry.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/bug.h>
+#include <linux/asn1.h>
+#include "oid_registry_data.c"
+
+MODULE_DESCRIPTION("OID Registry");
+MODULE_AUTHOR("Red Hat, Inc.");
+MODULE_LICENSE("GPL");
+
+/**
+ * look_up_OID - Find an OID registration for the specified data
+ * @data: Binary representation of the OID
+ * @datasize: Size of the binary representation
+ */
+enum OID look_up_OID(const void *data, size_t datasize)
+{
+	const unsigned char *octets = data;
+	enum OID oid;
+	unsigned char xhash;
+	unsigned i, j, k, hash;
+	size_t len;
+
+	/* Hash the OID data */
+	hash = datasize - 1;
+
+	for (i = 0; i < datasize; i++)
+		hash += octets[i] * 33;
+	hash = (hash >> 24) ^ (hash >> 16) ^ (hash >> 8) ^ hash;
+	hash &= 0xff;
+
+	/* Binary search the OID registry.  OIDs are stored in ascending order
+	 * of hash value then ascending order of size and then in ascending
+	 * order of reverse value.
+	 */
+	i = 0;
+	k = OID__NR;
+	while (i < k) {
+		j = (i + k) / 2;
+
+		xhash = oid_search_table[j].hash;
+		if (xhash > hash) {
+			k = j;
+			continue;
+		}
+		if (xhash < hash) {
+			i = j + 1;
+			continue;
+		}
+
+		oid = oid_search_table[j].oid;
+		len = oid_index[oid + 1] - oid_index[oid];
+		if (len > datasize) {
+			k = j;
+			continue;
+		}
+		if (len < datasize) {
+			i = j + 1;
+			continue;
+		}
+
+		/* Variation is most likely to be at the tail end of the
+		 * OID, so do the comparison in reverse.
+		 */
+		while (len > 0) {
+			unsigned char a = oid_data[oid_index[oid] + --len];
+			unsigned char b = octets[len];
+			if (a > b) {
+				k = j;
+				goto next;
+			}
+			if (a < b) {
+				i = j + 1;
+				goto next;
+			}
+		}
+		return oid;
+	next:
+		;
+	}
+
+	return OID__NR;
+}
+EXPORT_SYMBOL_GPL(look_up_OID);
+
+/**
+ * parse_OID - Parse an OID from a bytestream
+ * @data: Binary representation of the header + OID
+ * @datasize: Size of the binary representation
+ * @oid: Pointer to oid to return result
+ *
+ * Parse an OID from a bytestream that holds the OID in the format
+ * ASN1_OID | length | oid. The length indicator must equal to datasize - 2.
+ * -EBADMSG is returned if the bytestream is too short.
+ */
+int parse_OID(const void *data, size_t datasize, enum OID *oid)
+{
+	const unsigned char *v = data;
+
+	/* we need 2 bytes of header and at least 1 byte for oid */
+	if (datasize < 3 || v[0] != ASN1_OID || v[1] != datasize - 2)
+		return -EBADMSG;
+
+	*oid = look_up_OID(data + 2, datasize - 2);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(parse_OID);
+
+/*
+ * sprint_oid - Print an Object Identifier into a buffer
+ * @data: The encoded OID to print
+ * @datasize: The size of the encoded OID
+ * @buffer: The buffer to render into
+ * @bufsize: The size of the buffer
+ *
+ * The OID is rendered into the buffer in "a.b.c.d" format and the number of
+ * bytes is returned.  -EBADMSG is returned if the data could not be interpreted
+ * and -ENOBUFS if the buffer was too small.
+ */
+int sprint_oid(const void *data, size_t datasize, char *buffer, size_t bufsize)
+{
+	const unsigned char *v = data, *end = v + datasize;
+	unsigned long num;
+	unsigned char n;
+	size_t ret;
+	int count;
+
+	if (v >= end)
+		goto bad;
+
+	n = *v++;
+	ret = count = snprintf(buffer, bufsize, "%u.%u", n / 40, n % 40);
+	if (count >= bufsize)
+		return -ENOBUFS;
+	buffer += count;
+	bufsize -= count;
+
+	while (v < end) {
+		n = *v++;
+		if (!(n & 0x80)) {
+			num = n;
+		} else {
+			num = n & 0x7f;
+			do {
+				if (v >= end)
+					goto bad;
+				n = *v++;
+				num <<= 7;
+				num |= n & 0x7f;
+			} while (n & 0x80);
+		}
+		ret += count = snprintf(buffer, bufsize, ".%lu", num);
+		if (count >= bufsize)
+			return -ENOBUFS;
+		buffer += count;
+		bufsize -= count;
+	}
+
+	return ret;
+
+bad:
+	snprintf(buffer, bufsize, "(bad)");
+	return -EBADMSG;
+}
+EXPORT_SYMBOL_GPL(sprint_oid);