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, 60 insertions, 0 deletions

diff --git a/include/net/seg6_hmac.h b/include/net/seg6_hmac.h
new file mode 100644
index 000000000..e9f417259
--- /dev/null
+++ b/include/net/seg6_hmac.h
@@ -0,0 +1,60 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ *  SR-IPv6 implementation
+ *
+ *  Author:
+ *  David Lebrun <david.lebrun@uclouvain.be>
+ */
+
+#ifndef _NET_SEG6_HMAC_H
+#define _NET_SEG6_HMAC_H
+
+#include <crypto/sha1.h>
+#include <crypto/sha2.h>
+#include <net/flow.h>
+#include <net/ip6_fib.h>
+#include <net/sock.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <linux/route.h>
+#include <net/seg6.h>
+#include <linux/seg6_hmac.h>
+#include <linux/rhashtable-types.h>
+
+#define SEG6_HMAC_RING_SIZE		256
+
+struct seg6_hmac_info {
+	struct rhash_head node;
+	struct rcu_head rcu;
+
+	u32 hmackeyid;
+	/* The raw key, kept only so it can be returned back to userspace */
+	char secret[SEG6_HMAC_SECRET_LEN];
+	u8 slen;
+	u8 alg_id;
+	/* The prepared key, which the calculations actually use */
+	union {
+		struct hmac_sha1_key sha1;
+		struct hmac_sha256_key sha256;
+	} key;
+};
+
+extern int seg6_hmac_compute(struct seg6_hmac_info *hinfo,
+			     struct ipv6_sr_hdr *hdr, struct in6_addr *saddr,
+			     u8 *output);
+extern struct seg6_hmac_info *seg6_hmac_info_lookup(struct net *net, u32 key);
+extern int seg6_hmac_info_add(struct net *net, u32 key,
+			      struct seg6_hmac_info *hinfo);
+extern int seg6_hmac_info_del(struct net *net, u32 key);
+extern int seg6_push_hmac(struct net *net, struct in6_addr *saddr,
+			  struct ipv6_sr_hdr *srh);
+extern bool seg6_hmac_validate_skb(struct sk_buff *skb);
+#ifdef CONFIG_IPV6_SEG6_HMAC
+extern int seg6_hmac_net_init(struct net *net);
+extern void seg6_hmac_net_exit(struct net *net);
+#else
+static inline int seg6_hmac_net_init(struct net *net) { return 0; }
+static inline void seg6_hmac_net_exit(struct net *net) {}
+#endif
+
+#endif