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, 101 insertions, 0 deletions

diff --git a/tools/include/nolibc/getopt.h b/tools/include/nolibc/getopt.h
new file mode 100644
index 000000000..3ad140f69
--- /dev/null
+++ b/tools/include/nolibc/getopt.h
@@ -0,0 +1,101 @@
+/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
+/*
+ * getopt function definitions for NOLIBC, adapted from musl libc
+ * Copyright (C) 2005-2020 Rich Felker, et al.
+ * Copyright (C) 2025 Thomas Weißschuh <linux@weissschuh.net>
+ */
+
+/* make sure to include all global symbols */
+#include "nolibc.h"
+
+#ifndef _NOLIBC_GETOPT_H
+#define _NOLIBC_GETOPT_H
+
+struct FILE;
+static struct FILE *const stderr;
+static int fprintf(struct FILE *stream, const char *fmt, ...);
+
+__attribute__((weak,unused,section(".data.nolibc_getopt")))
+char *optarg;
+
+__attribute__((weak,unused,section(".data.nolibc_getopt")))
+int optind = 1, opterr = 1, optopt;
+
+static __attribute__((unused))
+int getopt(int argc, char * const argv[], const char *optstring)
+{
+	static int __optpos;
+	int i;
+	char c, d;
+	char *optchar;
+
+	if (!optind) {
+		__optpos = 0;
+		optind = 1;
+	}
+
+	if (optind >= argc || !argv[optind])
+		return -1;
+
+	if (argv[optind][0] != '-') {
+		if (optstring[0] == '-') {
+			optarg = argv[optind++];
+			return 1;
+		}
+		return -1;
+	}
+
+	if (!argv[optind][1])
+		return -1;
+
+	if (argv[optind][1] == '-' && !argv[optind][2])
+		return optind++, -1;
+
+	if (!__optpos)
+		__optpos++;
+	c = argv[optind][__optpos];
+	optchar = argv[optind] + __optpos;
+	__optpos++;
+
+	if (!argv[optind][__optpos]) {
+		optind++;
+		__optpos = 0;
+	}
+
+	if (optstring[0] == '-' || optstring[0] == '+')
+		optstring++;
+
+	i = 0;
+	d = 0;
+	do {
+		d = optstring[i++];
+	} while (d && d != c);
+
+	if (!d || d != c || c == ':') {
+		optopt = c;
+		if (optstring[0] != ':' && opterr)
+			fprintf(stderr, "%s: unrecognized option: %c\n", argv[0], *optchar);
+		return '?';
+	}
+	if (optstring[i] == ':') {
+		optarg = NULL;
+		if (optstring[i + 1] != ':' || __optpos) {
+			optarg = argv[optind++];
+			if (__optpos)
+				optarg += __optpos;
+			__optpos = 0;
+		}
+		if (optind > argc) {
+			optopt = c;
+			if (optstring[0] == ':')
+				return ':';
+			if (opterr)
+				fprintf(stderr, "%s: option requires argument: %c\n",
+					argv[0], *optchar);
+			return '?';
+		}
+	}
+	return c;
+}
+
+#endif /* _NOLIBC_GETOPT_H */