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, 237 insertions, 0 deletions

diff --git a/lib/ts_bm.c b/lib/ts_bm.c
new file mode 100644
index 000000000..676105e84
--- /dev/null
+++ b/lib/ts_bm.c
@@ -0,0 +1,237 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * lib/ts_bm.c		Boyer-Moore text search implementation
+ *
+ * Authors:	Pablo Neira Ayuso <pablo@eurodev.net>
+ *
+ * ==========================================================================
+ * 
+ *   Implements Boyer-Moore string matching algorithm:
+ *
+ *   [1] A Fast String Searching Algorithm, R.S. Boyer and Moore.
+ *       Communications of the Association for Computing Machinery, 
+ *       20(10), 1977, pp. 762-772.
+ *       https://www.cs.utexas.edu/users/moore/publications/fstrpos.pdf
+ *
+ *   [2] Handbook of Exact String Matching Algorithms, Thierry Lecroq, 2004
+ *       http://www-igm.univ-mlv.fr/~lecroq/string/string.pdf
+ *
+ *   Note: Since Boyer-Moore (BM) performs searches for matchings from right 
+ *   to left, it's still possible that a matching could be spread over 
+ *   multiple blocks, in that case this algorithm won't find any coincidence.
+ *   
+ *   If you're willing to ensure that such thing won't ever happen, use the
+ *   Knuth-Pratt-Morris (KMP) implementation instead. In conclusion, choose 
+ *   the proper string search algorithm depending on your setting. 
+ *
+ *   Say you're using the textsearch infrastructure for filtering, NIDS or 
+ *   any similar security focused purpose, then go KMP. Otherwise, if you 
+ *   really care about performance, say you're classifying packets to apply
+ *   Quality of Service (QoS) policies, and you don't mind about possible
+ *   matchings spread over multiple fragments, then go BM.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/ctype.h>
+#include <linux/textsearch.h>
+
+/* Alphabet size, use ASCII */
+#define ASIZE 256
+
+#if 0
+#define DEBUGP printk
+#else
+#define DEBUGP(args, format...)
+#endif
+
+struct ts_bm
+{
+	u8 *		pattern;
+	unsigned int	patlen;
+	unsigned int 	bad_shift[ASIZE];
+	unsigned int	good_shift[];
+};
+
+static unsigned int matchpat(const u8 *pattern, unsigned int patlen,
+			     const u8 *text, bool icase)
+{
+	unsigned int i;
+
+	for (i = 0; i < patlen; i++) {
+		u8 t = *(text-i);
+
+		if (icase)
+			t = toupper(t);
+
+		if (t != *(pattern-i))
+			break;
+	}
+
+	return i;
+}
+
+static unsigned int bm_find(struct ts_config *conf, struct ts_state *state)
+{
+	struct ts_bm *bm = ts_config_priv(conf);
+	unsigned int i, text_len, consumed = state->offset;
+	const u8 *text;
+	int bs;
+	const u8 icase = conf->flags & TS_IGNORECASE;
+
+	for (;;) {
+		int shift = bm->patlen - 1;
+
+		text_len = conf->get_next_block(consumed, &text, conf, state);
+
+		if (unlikely(text_len == 0))
+			break;
+
+		while (shift < text_len) {
+			DEBUGP("Searching in position %d (%c)\n",
+			       shift, text[shift]);
+
+			i = matchpat(&bm->pattern[bm->patlen-1], bm->patlen,
+				     &text[shift], icase);
+			if (i == bm->patlen) {
+				/* London calling... */
+				DEBUGP("found!\n");
+				return consumed + (shift-(bm->patlen-1));
+			}
+
+			bs = bm->bad_shift[text[shift-i]];
+
+			/* Now jumping to... */
+			shift = max_t(int, shift-i+bs, shift+bm->good_shift[i]);
+		}
+		consumed += text_len;
+	}
+
+	return UINT_MAX;
+}
+
+static int subpattern(u8 *pattern, int i, int j, int g)
+{
+	int x = i+g-1, y = j+g-1, ret = 0;
+
+	while(pattern[x--] == pattern[y--]) {
+		if (y < 0) {
+			ret = 1;
+			break;
+		}
+		if (--g == 0) {
+			ret = pattern[i-1] != pattern[j-1];
+			break;
+		}
+	}
+
+	return ret;
+}
+
+static void compute_prefix_tbl(struct ts_bm *bm, int flags)
+{
+	int i, j, g;
+
+	for (i = 0; i < ASIZE; i++)
+		bm->bad_shift[i] = bm->patlen;
+	for (i = 0; i < bm->patlen - 1; i++) {
+		bm->bad_shift[bm->pattern[i]] = bm->patlen - 1 - i;
+		if (flags & TS_IGNORECASE)
+			bm->bad_shift[tolower(bm->pattern[i])]
+			    = bm->patlen - 1 - i;
+	}
+
+	/* Compute the good shift array, used to match reocurrences 
+	 * of a subpattern */
+	bm->good_shift[0] = 1;
+	for (i = 1; i < bm->patlen; i++)
+		bm->good_shift[i] = bm->patlen;
+        for (i = bm->patlen-1, g = 1; i > 0; g++, i--) {
+		for (j = i-1; j >= 1-g ; j--)
+			if (subpattern(bm->pattern, i, j, g)) {
+				bm->good_shift[g] = bm->patlen-j-g;
+				break;
+			}
+	}
+}
+
+static struct ts_config *bm_init(const void *pattern, unsigned int len,
+				 gfp_t gfp_mask, int flags)
+{
+	struct ts_config *conf;
+	struct ts_bm *bm;
+	int i;
+	unsigned int prefix_tbl_len;
+	size_t priv_size;
+
+	/* Zero-length patterns would underflow bm_find()'s initial shift. */
+	if (unlikely(!len))
+		return ERR_PTR(-EINVAL);
+
+	/*
+	 * bm->pattern is stored immediately after the good_shift[] table.
+	 * Reject lengths that would wrap while sizing either region.
+	 */
+	if (unlikely(check_mul_overflow(len, sizeof(*bm->good_shift),
+					&prefix_tbl_len) ||
+		     check_add_overflow(sizeof(*bm), (size_t)len, &priv_size) ||
+		     check_add_overflow(priv_size, prefix_tbl_len, &priv_size)))
+		return ERR_PTR(-EINVAL);
+
+	conf = alloc_ts_config(priv_size, gfp_mask);
+	if (IS_ERR(conf))
+		return conf;
+
+	conf->flags = flags;
+	bm = ts_config_priv(conf);
+	bm->patlen = len;
+	bm->pattern = (u8 *) bm->good_shift + prefix_tbl_len;
+	if (flags & TS_IGNORECASE)
+		for (i = 0; i < len; i++)
+			bm->pattern[i] = toupper(((u8 *)pattern)[i]);
+	else
+		memcpy(bm->pattern, pattern, len);
+	compute_prefix_tbl(bm, flags);
+
+	return conf;
+}
+
+static void *bm_get_pattern(struct ts_config *conf)
+{
+	struct ts_bm *bm = ts_config_priv(conf);
+	return bm->pattern;
+}
+
+static unsigned int bm_get_pattern_len(struct ts_config *conf)
+{
+	struct ts_bm *bm = ts_config_priv(conf);
+	return bm->patlen;
+}
+
+static struct ts_ops bm_ops = {
+	.name		  = "bm",
+	.find		  = bm_find,
+	.init		  = bm_init,
+	.get_pattern	  = bm_get_pattern,
+	.get_pattern_len  = bm_get_pattern_len,
+	.owner		  = THIS_MODULE,
+	.list		  = LIST_HEAD_INIT(bm_ops.list)
+};
+
+static int __init init_bm(void)
+{
+	return textsearch_register(&bm_ops);
+}
+
+static void __exit exit_bm(void)
+{
+	textsearch_unregister(&bm_ops);
+}
+
+MODULE_DESCRIPTION("Boyer-Moore text search implementation");
+MODULE_LICENSE("GPL");
+
+module_init(init_bm);
+module_exit(exit_bm);