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, 67 insertions, 0 deletions

diff --git a/include/crypto/poly1305.h b/include/crypto/poly1305.h
new file mode 100644
index 000000000..190beb427
--- /dev/null
+++ b/include/crypto/poly1305.h
@@ -0,0 +1,67 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Common values for the Poly1305 algorithm
+ */
+
+#ifndef _CRYPTO_POLY1305_H
+#define _CRYPTO_POLY1305_H
+
+#include <linux/types.h>
+
+#define POLY1305_BLOCK_SIZE	16
+#define POLY1305_KEY_SIZE	32
+#define POLY1305_DIGEST_SIZE	16
+
+/* The poly1305_key and poly1305_state types are mostly opaque and
+ * implementation-defined. Limbs might be in base 2^64 or base 2^26, or
+ * different yet. The union type provided keeps these 64-bit aligned for the
+ * case in which this is implemented using 64x64 multiplies.
+ */
+
+struct poly1305_key {
+	union {
+		u32 r[5];
+		u64 r64[3];
+	};
+};
+
+struct poly1305_core_key {
+	struct poly1305_key key;
+	struct poly1305_key precomputed_s;
+};
+
+struct poly1305_state {
+	union {
+		u32 h[5];
+		u64 h64[3];
+	};
+};
+
+/* Combined state for block function. */
+struct poly1305_block_state {
+	/* accumulator */
+	struct poly1305_state h;
+	/* key */
+	union {
+		struct poly1305_key opaque_r[CONFIG_CRYPTO_LIB_POLY1305_RSIZE];
+		struct poly1305_core_key core_r;
+	};
+};
+
+struct poly1305_desc_ctx {
+	/* partial buffer */
+	u8 buf[POLY1305_BLOCK_SIZE];
+	/* bytes used in partial buffer */
+	unsigned int buflen;
+	/* finalize key */
+	u32 s[4];
+	struct poly1305_block_state state;
+};
+
+void poly1305_init(struct poly1305_desc_ctx *desc,
+		   const u8 key[at_least POLY1305_KEY_SIZE]);
+void poly1305_update(struct poly1305_desc_ctx *desc,
+		     const u8 *src, unsigned int nbytes);
+void poly1305_final(struct poly1305_desc_ctx *desc, u8 *digest);
+
+#endif