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, 119 insertions, 0 deletions

diff --git a/fs/hfs/string.c b/fs/hfs/string.c
new file mode 100644
index 000000000..0cfa35e82
--- /dev/null
+++ b/fs/hfs/string.c
@@ -0,0 +1,119 @@
+/*
+ *  linux/fs/hfs/string.c
+ *
+ * Copyright (C) 1995-1997  Paul H. Hargrove
+ * (C) 2003 Ardis Technologies <roman@ardistech.com>
+ * This file may be distributed under the terms of the GNU General Public License.
+ *
+ * This file contains the string comparison function for the
+ * Macintosh character set.
+ *
+ * The code in this file is derived from code which is copyright
+ * 1986, 1989, 1990 by Abacus Research and Development, Inc. (ARDI)
+ * It is used here by the permission of ARDI's president Cliff Matthews.
+ */
+
+#include "hfs_fs.h"
+#include <linux/dcache.h>
+
+#include <kunit/visibility.h>
+
+/*================ File-local variables ================*/
+
+/*
+ * unsigned char caseorder[]
+ *
+ * Defines the lexical ordering of characters on the Macintosh
+ *
+ * Composition of the 'casefold' and 'order' tables from ARDI's code
+ * with the entry for 0x20 changed to match that for 0xCA to remove
+ * special case for those two characters.
+ */
+static unsigned char caseorder[256] = {
+	0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0A,0x0B,0x0C,0x0D,0x0E,0x0F,
+	0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17,0x18,0x19,0x1A,0x1B,0x1C,0x1D,0x1E,0x1F,
+	0x20,0x22,0x23,0x28,0x29,0x2A,0x2B,0x2C,0x2F,0x30,0x31,0x32,0x33,0x34,0x35,0x36,
+	0x37,0x38,0x39,0x3A,0x3B,0x3C,0x3D,0x3E,0x3F,0x40,0x41,0x42,0x43,0x44,0x45,0x46,
+	0x47,0x48,0x57,0x59,0x5D,0x5F,0x66,0x68,0x6A,0x6C,0x72,0x74,0x76,0x78,0x7A,0x7E,
+	0x8C,0x8E,0x90,0x92,0x95,0x97,0x9E,0xA0,0xA2,0xA4,0xA7,0xA9,0xAA,0xAB,0xAC,0xAD,
+	0x4E,0x48,0x57,0x59,0x5D,0x5F,0x66,0x68,0x6A,0x6C,0x72,0x74,0x76,0x78,0x7A,0x7E,
+	0x8C,0x8E,0x90,0x92,0x95,0x97,0x9E,0xA0,0xA2,0xA4,0xA7,0xAF,0xB0,0xB1,0xB2,0xB3,
+	0x4A,0x4C,0x5A,0x60,0x7B,0x7F,0x98,0x4F,0x49,0x51,0x4A,0x4B,0x4C,0x5A,0x60,0x63,
+	0x64,0x65,0x6E,0x6F,0x70,0x71,0x7B,0x84,0x85,0x86,0x7F,0x80,0x9A,0x9B,0x9C,0x98,
+	0xB4,0xB5,0xB6,0xB7,0xB8,0xB9,0xBA,0x94,0xBB,0xBC,0xBD,0xBE,0xBF,0xC0,0x4D,0x81,
+	0xC1,0xC2,0xC3,0xC4,0xC5,0xC6,0xC7,0xC8,0xC9,0xCA,0xCB,0x55,0x8A,0xCC,0x4D,0x81,
+	0xCD,0xCE,0xCF,0xD0,0xD1,0xD2,0xD3,0x26,0x27,0xD4,0x20,0x49,0x4B,0x80,0x82,0x82,
+	0xD5,0xD6,0x24,0x25,0x2D,0x2E,0xD7,0xD8,0xA6,0xD9,0xDA,0xDB,0xDC,0xDD,0xDE,0xDF,
+	0xE0,0xE1,0xE2,0xE3,0xE4,0xE5,0xE6,0xE7,0xE8,0xE9,0xEA,0xEB,0xEC,0xED,0xEE,0xEF,
+	0xF0,0xF1,0xF2,0xF3,0xF4,0xF5,0xF6,0xF7,0xF8,0xF9,0xFA,0xFB,0xFC,0xFD,0xFE,0xFF
+};
+
+/*================ Global functions ================*/
+
+/*
+ * Hash a string to an integer in a case-independent way
+ */
+int hfs_hash_dentry(const struct dentry *dentry, struct qstr *this)
+{
+	const unsigned char *name = this->name;
+	unsigned int hash, len = this->len;
+
+	if (len > HFS_NAMELEN)
+		len = HFS_NAMELEN;
+
+	hash = init_name_hash(dentry);
+	for (; len; len--)
+		hash = partial_name_hash(caseorder[*name++], hash);
+	this->hash = end_name_hash(hash);
+	return 0;
+}
+EXPORT_SYMBOL_IF_KUNIT(hfs_hash_dentry);
+
+/*
+ * Compare two strings in the HFS filename character ordering
+ * Returns positive, negative, or zero, not just 0 or (+/-)1
+ *
+ * Equivalent to ARDI's call:
+ *	ROMlib_RelString(s1+1, s2+1, true, false, (s1[0]<<16) | s2[0])
+ */
+int hfs_strcmp(const unsigned char *s1, unsigned int len1,
+	       const unsigned char *s2, unsigned int len2)
+{
+	int len, tmp;
+
+	len = (len1 > len2) ? len2 : len1;
+
+	while (len--) {
+		tmp = (int)caseorder[*(s1++)] - (int)caseorder[*(s2++)];
+		if (tmp)
+			return tmp;
+	}
+	return len1 - len2;
+}
+EXPORT_SYMBOL_IF_KUNIT(hfs_strcmp);
+
+/*
+ * Test for equality of two strings in the HFS filename character ordering.
+ * return 1 on failure and 0 on success
+ */
+int hfs_compare_dentry(const struct dentry *dentry,
+		unsigned int len, const char *str, const struct qstr *name)
+{
+	const unsigned char *n1, *n2;
+
+	if (len >= HFS_NAMELEN) {
+		if (name->len < HFS_NAMELEN)
+			return 1;
+		len = HFS_NAMELEN;
+	} else if (len != name->len)
+		return 1;
+
+	n1 = str;
+	n2 = name->name;
+	while (len--) {
+		if (caseorder[*n1++] != caseorder[*n2++])
+			return 1;
+	}
+	return 0;
+}
+EXPORT_SYMBOL_IF_KUNIT(hfs_compare_dentry);