From a5969cabbb4660eab42b6ef0412cbbd1200cf14d Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Sat, 12 Oct 2024 07:10:09 +0000
Subject: [PATCH] 修改led为gpio

---
 kernel/include/linux/rcupdate.h |  412 +++++++++++++++++++++++++++++++++++++++-------------------
 1 files changed, 274 insertions(+), 138 deletions(-)

diff --git a/kernel/include/linux/rcupdate.h b/kernel/include/linux/rcupdate.h
index 08d64e5..a833efa 100644
--- a/kernel/include/linux/rcupdate.h
+++ b/kernel/include/linux/rcupdate.h
@@ -1,25 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Read-Copy Update mechanism for mutual exclusion
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
  *
  * Copyright IBM Corporation, 2001
  *
  * Author: Dipankar Sarma <dipankar@in.ibm.com>
  *
- * Based on the original work by Paul McKenney <paulmck@us.ibm.com>
+ * Based on the original work by Paul McKenney <paulmck@vnet.ibm.com>
  * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
  * Papers:
  * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf
@@ -42,34 +29,23 @@
 #include <linux/lockdep.h>
 #include <asm/processor.h>
 #include <linux/cpumask.h>
-#include <linux/rcu_assign_pointer.h>
 
 #define ULONG_CMP_GE(a, b)	(ULONG_MAX / 2 >= (a) - (b))
 #define ULONG_CMP_LT(a, b)	(ULONG_MAX / 2 < (a) - (b))
 #define ulong2long(a)		(*(long *)(&(a)))
+#define USHORT_CMP_GE(a, b)	(USHRT_MAX / 2 >= (unsigned short)((a) - (b)))
+#define USHORT_CMP_LT(a, b)	(USHRT_MAX / 2 < (unsigned short)((a) - (b)))
 
 /* Exported common interfaces */
-
-#ifdef CONFIG_PREEMPT_RCU
 void call_rcu(struct rcu_head *head, rcu_callback_t func);
-#else /* #ifdef CONFIG_PREEMPT_RCU */
-#define	call_rcu	call_rcu_sched
-#endif /* #else #ifdef CONFIG_PREEMPT_RCU */
-
-#ifdef CONFIG_PREEMPT_RT_FULL
-#define call_rcu_bh	call_rcu
-#else
-void call_rcu_bh(struct rcu_head *head, rcu_callback_t func);
-#endif
-void call_rcu_sched(struct rcu_head *head, rcu_callback_t func);
-void synchronize_sched(void);
 void rcu_barrier_tasks(void);
+void rcu_barrier_tasks_rude(void);
+void synchronize_rcu(void);
 
 #ifdef CONFIG_PREEMPT_RCU
 
 void __rcu_read_lock(void);
 void __rcu_read_unlock(void);
-void synchronize_rcu(void);
 
 /*
  * Defined as a macro as it is a very low level header included from
@@ -78,13 +54,14 @@
  * types of kernel builds, the rcu_read_lock() nesting depth is unknowable.
  */
 #define rcu_preempt_depth() (current->rcu_read_lock_nesting)
-#ifndef CONFIG_PREEMPT_RT_FULL
-#define sched_rcu_preempt_depth()	rcu_preempt_depth()
-#else
-static inline int sched_rcu_preempt_depth(void) { return 0; }
-#endif
 
 #else /* #ifdef CONFIG_PREEMPT_RCU */
+
+#ifdef CONFIG_TINY_RCU
+#define rcu_read_unlock_strict() do { } while (0)
+#else
+void rcu_read_unlock_strict(void);
+#endif
 
 static inline void __rcu_read_lock(void)
 {
@@ -94,11 +71,7 @@
 static inline void __rcu_read_unlock(void)
 {
 	preempt_enable();
-}
-
-static inline void synchronize_rcu(void)
-{
-	synchronize_sched();
+	rcu_read_unlock_strict();
 }
 
 static inline int rcu_preempt_depth(void)
@@ -106,18 +79,20 @@
 	return 0;
 }
 
-#define sched_rcu_preempt_depth()	rcu_preempt_depth()
-
 #endif /* #else #ifdef CONFIG_PREEMPT_RCU */
 
 /* Internal to kernel */
 void rcu_init(void);
-extern int rcu_scheduler_active __read_mostly;
-void rcu_sched_qs(void);
-void rcu_bh_qs(void);
-void rcu_check_callbacks(int user);
+extern int rcu_scheduler_active;
+void rcu_sched_clock_irq(int user);
 void rcu_report_dead(unsigned int cpu);
 void rcutree_migrate_callbacks(int cpu);
+
+#ifdef CONFIG_TASKS_RCU_GENERIC
+void rcu_init_tasks_generic(void);
+#else
+static inline void rcu_init_tasks_generic(void) { }
+#endif
 
 #ifdef CONFIG_RCU_STALL_COMMON
 void rcu_sysrq_start(void);
@@ -137,19 +112,20 @@
 
 #ifdef CONFIG_RCU_NOCB_CPU
 void rcu_init_nohz(void);
+void rcu_nocb_flush_deferred_wakeup(void);
 #else /* #ifdef CONFIG_RCU_NOCB_CPU */
 static inline void rcu_init_nohz(void) { }
+static inline void rcu_nocb_flush_deferred_wakeup(void) { }
 #endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */
 
 /**
  * RCU_NONIDLE - Indicate idle-loop code that needs RCU readers
  * @a: Code that RCU needs to pay attention to.
  *
- * RCU, RCU-bh, and RCU-sched read-side critical sections are forbidden
- * in the inner idle loop, that is, between the rcu_idle_enter() and
- * the rcu_idle_exit() -- RCU will happily ignore any such read-side
- * critical sections.  However, things like powertop need tracepoints
- * in the inner idle loop.
+ * RCU read-side critical sections are forbidden in the inner idle loop,
+ * that is, between the rcu_idle_enter() and the rcu_idle_exit() -- RCU
+ * will happily ignore any such read-side critical sections.  However,
+ * things like powertop need tracepoints in the inner idle loop.
  *
  * This macro provides the way out:  RCU_NONIDLE(do_something_with_RCU())
  * will tell RCU that it needs to pay attention, invoke its argument
@@ -171,40 +147,70 @@
  * Note a quasi-voluntary context switch for RCU-tasks's benefit.
  * This is a macro rather than an inline function to avoid #include hell.
  */
-#ifdef CONFIG_TASKS_RCU
-#define rcu_tasks_qs(t) \
-	do { \
-		if (READ_ONCE((t)->rcu_tasks_holdout)) \
-			WRITE_ONCE((t)->rcu_tasks_holdout, false); \
-	} while (0)
-#define rcu_note_voluntary_context_switch(t) \
-	do { \
-		rcu_all_qs(); \
-		rcu_tasks_qs(t); \
+#ifdef CONFIG_TASKS_RCU_GENERIC
+
+# ifdef CONFIG_TASKS_RCU
+# define rcu_tasks_classic_qs(t, preempt)				\
+	do {								\
+		if (!(preempt) && READ_ONCE((t)->rcu_tasks_holdout))	\
+			WRITE_ONCE((t)->rcu_tasks_holdout, false);	\
 	} while (0)
 void call_rcu_tasks(struct rcu_head *head, rcu_callback_t func);
 void synchronize_rcu_tasks(void);
+# else
+# define rcu_tasks_classic_qs(t, preempt) do { } while (0)
+# define call_rcu_tasks call_rcu
+# define synchronize_rcu_tasks synchronize_rcu
+# endif
+
+# ifdef CONFIG_TASKS_TRACE_RCU
+# define rcu_tasks_trace_qs(t)						\
+	do {								\
+		if (!likely(READ_ONCE((t)->trc_reader_checked)) &&	\
+		    !unlikely(READ_ONCE((t)->trc_reader_nesting))) {	\
+			smp_store_release(&(t)->trc_reader_checked, true); \
+			smp_mb(); /* Readers partitioned by store. */	\
+		}							\
+	} while (0)
+# else
+# define rcu_tasks_trace_qs(t) do { } while (0)
+# endif
+
+#define rcu_tasks_qs(t, preempt)					\
+do {									\
+	rcu_tasks_classic_qs((t), (preempt));				\
+	rcu_tasks_trace_qs((t));					\
+} while (0)
+
+# ifdef CONFIG_TASKS_RUDE_RCU
+void call_rcu_tasks_rude(struct rcu_head *head, rcu_callback_t func);
+void synchronize_rcu_tasks_rude(void);
+# endif
+
+#define rcu_note_voluntary_context_switch(t) rcu_tasks_qs(t, false)
 void exit_tasks_rcu_start(void);
+void exit_tasks_rcu_stop(void);
 void exit_tasks_rcu_finish(void);
-#else /* #ifdef CONFIG_TASKS_RCU */
-#define rcu_tasks_qs(t)	do { } while (0)
-#define rcu_note_voluntary_context_switch(t)		rcu_all_qs()
-#define call_rcu_tasks call_rcu_sched
-#define synchronize_rcu_tasks synchronize_sched
+#else /* #ifdef CONFIG_TASKS_RCU_GENERIC */
+#define rcu_tasks_qs(t, preempt) do { } while (0)
+#define rcu_note_voluntary_context_switch(t) do { } while (0)
+#define call_rcu_tasks call_rcu
+#define synchronize_rcu_tasks synchronize_rcu
 static inline void exit_tasks_rcu_start(void) { }
+static inline void exit_tasks_rcu_stop(void) { }
 static inline void exit_tasks_rcu_finish(void) { }
-#endif /* #else #ifdef CONFIG_TASKS_RCU */
+#endif /* #else #ifdef CONFIG_TASKS_RCU_GENERIC */
 
 /**
  * cond_resched_tasks_rcu_qs - Report potential quiescent states to RCU
  *
  * This macro resembles cond_resched(), except that it is defined to
  * report potential quiescent states to RCU-tasks even if the cond_resched()
- * machinery were to be shut off, as some advocate for PREEMPT kernels.
+ * machinery were to be shut off, as some advocate for PREEMPTION kernels.
  */
 #define cond_resched_tasks_rcu_qs() \
 do { \
-	rcu_tasks_qs(current); \
+	rcu_tasks_qs(current, false); \
 	cond_resched(); \
 } while (0)
 
@@ -213,7 +219,7 @@
  * TREE_RCU and rcu_barrier_() primitives in TINY_RCU.
  */
 
-#if defined(CONFIG_TREE_RCU) || defined(CONFIG_PREEMPT_RCU)
+#if defined(CONFIG_TREE_RCU)
 #include <linux/rcutree.h>
 #elif defined(CONFIG_TINY_RCU)
 #include <linux/rcutiny.h>
@@ -256,7 +262,7 @@
 
 static inline void rcu_lock_release(struct lockdep_map *map)
 {
-	lock_release(map, 1, _THIS_IP_);
+	lock_release(map, _THIS_IP_);
 }
 
 extern struct lockdep_map rcu_lock_map;
@@ -265,15 +271,9 @@
 extern struct lockdep_map rcu_callback_map;
 int debug_lockdep_rcu_enabled(void);
 int rcu_read_lock_held(void);
-#ifdef CONFIG_PREEMPT_RT_FULL
-static inline int rcu_read_lock_bh_held(void)
-{
-	return rcu_read_lock_held();
-}
-#else
 int rcu_read_lock_bh_held(void);
-#endif
 int rcu_read_lock_sched_held(void);
+int rcu_read_lock_any_held(void);
 
 #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 
@@ -294,6 +294,12 @@
 {
 	return !preemptible();
 }
+
+static inline int rcu_read_lock_any_held(void)
+{
+	return !preemptible();
+}
+
 #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 
 #ifdef CONFIG_PROVE_RCU
@@ -302,11 +308,18 @@
  * RCU_LOCKDEP_WARN - emit lockdep splat if specified condition is met
  * @c: condition to check
  * @s: informative message
+ *
+ * This checks debug_lockdep_rcu_enabled() before checking (c) to
+ * prevent early boot splats due to lockdep not yet being initialized,
+ * and rechecks it after checking (c) to prevent false-positive splats
+ * due to races with lockdep being disabled.  See commit 3066820034b5dd
+ * ("rcu: Reject RCU_LOCKDEP_WARN() false positives") for more detail.
  */
 #define RCU_LOCKDEP_WARN(c, s)						\
 	do {								\
-		static bool __section(.data.unlikely) __warned;		\
-		if (debug_lockdep_rcu_enabled() && !__warned && (c)) {	\
+		static bool __section(".data.unlikely") __warned;	\
+		if (debug_lockdep_rcu_enabled() && (c) &&		\
+		    debug_lockdep_rcu_enabled() && !__warned) {		\
 			__warned = true;				\
 			lockdep_rcu_suspicious(__FILE__, __LINE__, s);	\
 		}							\
@@ -342,22 +355,21 @@
  * Helper functions for rcu_dereference_check(), rcu_dereference_protected()
  * and rcu_assign_pointer().  Some of these could be folded into their
  * callers, but they are left separate in order to ease introduction of
- * multiple flavors of pointers to match the multiple flavors of RCU
- * (e.g., __rcu_bh, * __rcu_sched, and __srcu), should this make sense in
- * the future.
+ * multiple pointers markings to match different RCU implementations
+ * (e.g., __srcu), should this make sense in the future.
  */
 
 #ifdef __CHECKER__
-#define rcu_dereference_sparse(p, space) \
+#define rcu_check_sparse(p, space) \
 	((void)(((typeof(*p) space *)p) == p))
 #else /* #ifdef __CHECKER__ */
-#define rcu_dereference_sparse(p, space)
+#define rcu_check_sparse(p, space)
 #endif /* #else #ifdef __CHECKER__ */
 
 #define __rcu_access_pointer(p, space) \
 ({ \
 	typeof(*p) *_________p1 = (typeof(*p) *__force)READ_ONCE(p); \
-	rcu_dereference_sparse(p, space); \
+	rcu_check_sparse(p, space); \
 	((typeof(*p) __force __kernel *)(_________p1)); \
 })
 #define __rcu_dereference_check(p, c, space) \
@@ -365,13 +377,13 @@
 	/* Dependency order vs. p above. */ \
 	typeof(*p) *________p1 = (typeof(*p) *__force)READ_ONCE(p); \
 	RCU_LOCKDEP_WARN(!(c), "suspicious rcu_dereference_check() usage"); \
-	rcu_dereference_sparse(p, space); \
+	rcu_check_sparse(p, space); \
 	((typeof(*p) __force __kernel *)(________p1)); \
 })
 #define __rcu_dereference_protected(p, c, space) \
 ({ \
 	RCU_LOCKDEP_WARN(!(c), "suspicious rcu_dereference_protected() usage"); \
-	rcu_dereference_sparse(p, space); \
+	rcu_check_sparse(p, space); \
 	((typeof(*p) __force __kernel *)(p)); \
 })
 #define rcu_dereference_raw(p) \
@@ -382,20 +394,70 @@
 })
 
 /**
- * rcu_swap_protected() - swap an RCU and a regular pointer
- * @rcu_ptr: RCU pointer
- * @ptr: regular pointer
- * @c: the conditions under which the dereference will take place
- *
- * Perform swap(@rcu_ptr, @ptr) where @rcu_ptr is an RCU-annotated pointer and
- * @c is the argument that is passed to the rcu_dereference_protected() call
- * used to read that pointer.
+ * RCU_INITIALIZER() - statically initialize an RCU-protected global variable
+ * @v: The value to statically initialize with.
  */
-#define rcu_swap_protected(rcu_ptr, ptr, c) do {			\
+#define RCU_INITIALIZER(v) (typeof(*(v)) __force __rcu *)(v)
+
+/**
+ * rcu_assign_pointer() - assign to RCU-protected pointer
+ * @p: pointer to assign to
+ * @v: value to assign (publish)
+ *
+ * Assigns the specified value to the specified RCU-protected
+ * pointer, ensuring that any concurrent RCU readers will see
+ * any prior initialization.
+ *
+ * Inserts memory barriers on architectures that require them
+ * (which is most of them), and also prevents the compiler from
+ * reordering the code that initializes the structure after the pointer
+ * assignment.  More importantly, this call documents which pointers
+ * will be dereferenced by RCU read-side code.
+ *
+ * In some special cases, you may use RCU_INIT_POINTER() instead
+ * of rcu_assign_pointer().  RCU_INIT_POINTER() is a bit faster due
+ * to the fact that it does not constrain either the CPU or the compiler.
+ * That said, using RCU_INIT_POINTER() when you should have used
+ * rcu_assign_pointer() is a very bad thing that results in
+ * impossible-to-diagnose memory corruption.  So please be careful.
+ * See the RCU_INIT_POINTER() comment header for details.
+ *
+ * Note that rcu_assign_pointer() evaluates each of its arguments only
+ * once, appearances notwithstanding.  One of the "extra" evaluations
+ * is in typeof() and the other visible only to sparse (__CHECKER__),
+ * neither of which actually execute the argument.  As with most cpp
+ * macros, this execute-arguments-only-once property is important, so
+ * please be careful when making changes to rcu_assign_pointer() and the
+ * other macros that it invokes.
+ */
+#define rcu_assign_pointer(p, v)					      \
+do {									      \
+	uintptr_t _r_a_p__v = (uintptr_t)(v);				      \
+	rcu_check_sparse(p, __rcu);					      \
+									      \
+	if (__builtin_constant_p(v) && (_r_a_p__v) == (uintptr_t)NULL)	      \
+		WRITE_ONCE((p), (typeof(p))(_r_a_p__v));		      \
+	else								      \
+		smp_store_release(&p, RCU_INITIALIZER((typeof(p))_r_a_p__v)); \
+} while (0)
+
+/**
+ * rcu_replace_pointer() - replace an RCU pointer, returning its old value
+ * @rcu_ptr: RCU pointer, whose old value is returned
+ * @ptr: regular pointer
+ * @c: the lockdep conditions under which the dereference will take place
+ *
+ * Perform a replacement, where @rcu_ptr is an RCU-annotated
+ * pointer and @c is the lockdep argument that is passed to the
+ * rcu_dereference_protected() call used to read that pointer.  The old
+ * value of @rcu_ptr is returned, and @rcu_ptr is set to @ptr.
+ */
+#define rcu_replace_pointer(rcu_ptr, ptr, c)				\
+({									\
 	typeof(ptr) __tmp = rcu_dereference_protected((rcu_ptr), (c));	\
 	rcu_assign_pointer((rcu_ptr), (ptr));				\
-	(ptr) = __tmp;							\
-} while (0)
+	__tmp;								\
+})
 
 /**
  * rcu_access_pointer() - fetch RCU pointer with no dereferencing
@@ -482,7 +544,7 @@
  * The no-tracing version of rcu_dereference_raw() must not call
  * rcu_read_lock_held().
  */
-#define rcu_dereference_raw_notrace(p) __rcu_dereference_check((p), 1, __rcu)
+#define rcu_dereference_raw_check(p) __rcu_dereference_check((p), 1, __rcu)
 
 /**
  * rcu_dereference_protected() - fetch RCU pointer when updates prevented
@@ -579,12 +641,12 @@
  *
  * You can avoid reading and understanding the next paragraph by
  * following this rule: don't put anything in an rcu_read_lock() RCU
- * read-side critical section that would block in a !PREEMPT kernel.
+ * read-side critical section that would block in a !PREEMPTION kernel.
  * But if you want the full story, read on!
  *
- * In non-preemptible RCU implementations (TREE_RCU and TINY_RCU),
+ * In non-preemptible RCU implementations (pure TREE_RCU and TINY_RCU),
  * it is illegal to block while in an RCU read-side critical section.
- * In preemptible RCU implementations (PREEMPT_RCU) in CONFIG_PREEMPT
+ * In preemptible RCU implementations (PREEMPT_RCU) in CONFIG_PREEMPTION
  * kernel builds, RCU read-side critical sections may be preempted,
  * but explicit blocking is illegal.  Finally, in preemptible RCU
  * implementations in real-time (with -rt patchset) kernel builds, RCU
@@ -655,14 +717,9 @@
 /**
  * rcu_read_lock_bh() - mark the beginning of an RCU-bh critical section
  *
- * This is equivalent of rcu_read_lock(), but to be used when updates
- * are being done using call_rcu_bh() or synchronize_rcu_bh(). Since
- * both call_rcu_bh() and synchronize_rcu_bh() consider completion of a
- * softirq handler to be a quiescent state, a process in RCU read-side
- * critical section must be protected by disabling softirqs. Read-side
- * critical sections in interrupt context can use just rcu_read_lock(),
- * though this should at least be commented to avoid confusing people
- * reading the code.
+ * This is equivalent of rcu_read_lock(), but also disables softirqs.
+ * Note that anything else that disables softirqs can also serve as
+ * an RCU read-side critical section.
  *
  * Note that rcu_read_lock_bh() and the matching rcu_read_unlock_bh()
  * must occur in the same context, for example, it is illegal to invoke
@@ -672,41 +729,32 @@
 static inline void rcu_read_lock_bh(void)
 {
 	local_bh_disable();
-#ifdef CONFIG_PREEMPT_RT_FULL
-	rcu_read_lock();
-#else
 	__acquire(RCU_BH);
 	rcu_lock_acquire(&rcu_bh_lock_map);
 	RCU_LOCKDEP_WARN(!rcu_is_watching(),
 			 "rcu_read_lock_bh() used illegally while idle");
-#endif
 }
 
-/*
- * rcu_read_unlock_bh - marks the end of a softirq-only RCU critical section
+/**
+ * rcu_read_unlock_bh() - marks the end of a softirq-only RCU critical section
  *
  * See rcu_read_lock_bh() for more information.
  */
 static inline void rcu_read_unlock_bh(void)
 {
-#ifdef CONFIG_PREEMPT_RT_FULL
-	rcu_read_unlock();
-#else
 	RCU_LOCKDEP_WARN(!rcu_is_watching(),
 			 "rcu_read_unlock_bh() used illegally while idle");
 	rcu_lock_release(&rcu_bh_lock_map);
 	__release(RCU_BH);
-#endif
 	local_bh_enable();
 }
 
 /**
  * rcu_read_lock_sched() - mark the beginning of a RCU-sched critical section
  *
- * This is equivalent of rcu_read_lock(), but to be used when updates
- * are being done using call_rcu_sched() or synchronize_rcu_sched().
- * Read-side critical sections can also be introduced by anything that
- * disables preemption, including local_irq_disable() and friends.
+ * This is equivalent of rcu_read_lock(), but disables preemption.
+ * Read-side critical sections can also be introduced by anything else
+ * that disables preemption, including local_irq_disable() and friends.
  *
  * Note that rcu_read_lock_sched() and the matching rcu_read_unlock_sched()
  * must occur in the same context, for example, it is illegal to invoke
@@ -729,10 +777,10 @@
 	__acquire(RCU_SCHED);
 }
 
-/*
- * rcu_read_unlock_sched - marks the end of a RCU-classic critical section
+/**
+ * rcu_read_unlock_sched() - marks the end of a RCU-classic critical section
  *
- * See rcu_read_lock_sched for more information.
+ * See rcu_read_lock_sched() for more information.
  */
 static inline void rcu_read_unlock_sched(void)
 {
@@ -790,7 +838,7 @@
  */
 #define RCU_INIT_POINTER(p, v) \
 	do { \
-		rcu_dereference_sparse(p, __rcu); \
+		rcu_check_sparse(p, __rcu); \
 		WRITE_ONCE(p, RCU_INITIALIZER(v)); \
 	} while (0)
 
@@ -806,23 +854,23 @@
 
 /*
  * Does the specified offset indicate that the corresponding rcu_head
- * structure can be handled by kfree_rcu()?
+ * structure can be handled by kvfree_rcu()?
  */
-#define __is_kfree_rcu_offset(offset) ((offset) < 4096)
+#define __is_kvfree_rcu_offset(offset) ((offset) < 4096)
 
 /*
  * Helper macro for kfree_rcu() to prevent argument-expansion eyestrain.
  */
-#define __kfree_rcu(head, offset) \
+#define __kvfree_rcu(head, offset) \
 	do { \
-		BUILD_BUG_ON(!__is_kfree_rcu_offset(offset)); \
-		kfree_call_rcu(head, (rcu_callback_t)(unsigned long)(offset)); \
+		BUILD_BUG_ON(!__is_kvfree_rcu_offset(offset)); \
+		kvfree_call_rcu(head, (rcu_callback_t)(unsigned long)(offset)); \
 	} while (0)
 
 /**
  * kfree_rcu() - kfree an object after a grace period.
  * @ptr:	pointer to kfree
- * @rcu_head:	the name of the struct rcu_head within the type of @ptr.
+ * @rhf:	the name of the struct rcu_head within the type of @ptr.
  *
  * Many rcu callbacks functions just call kfree() on the base structure.
  * These functions are trivial, but their size adds up, and furthermore
@@ -835,7 +883,7 @@
  * Because the functions are not allowed in the low-order 4096 bytes of
  * kernel virtual memory, offsets up to 4095 bytes can be accommodated.
  * If the offset is larger than 4095 bytes, a compile-time error will
- * be generated in __kfree_rcu().  If this error is triggered, you can
+ * be generated in __kvfree_rcu(). If this error is triggered, you can
  * either fall back to use of call_rcu() or rearrange the structure to
  * position the rcu_head structure into the first 4096 bytes.
  *
@@ -845,9 +893,52 @@
  * The BUILD_BUG_ON check must not involve any function calls, hence the
  * checks are done in macros here.
  */
-#define kfree_rcu(ptr, rcu_head)					\
-	__kfree_rcu(&((ptr)->rcu_head), offsetof(typeof(*(ptr)), rcu_head))
+#define kfree_rcu(ptr, rhf)						\
+do {									\
+	typeof (ptr) ___p = (ptr);					\
+									\
+	if (___p)							\
+		__kvfree_rcu(&((___p)->rhf), offsetof(typeof(*(ptr)), rhf)); \
+} while (0)
 
+/**
+ * kvfree_rcu() - kvfree an object after a grace period.
+ *
+ * This macro consists of one or two arguments and it is
+ * based on whether an object is head-less or not. If it
+ * has a head then a semantic stays the same as it used
+ * to be before:
+ *
+ *     kvfree_rcu(ptr, rhf);
+ *
+ * where @ptr is a pointer to kvfree(), @rhf is the name
+ * of the rcu_head structure within the type of @ptr.
+ *
+ * When it comes to head-less variant, only one argument
+ * is passed and that is just a pointer which has to be
+ * freed after a grace period. Therefore the semantic is
+ *
+ *     kvfree_rcu(ptr);
+ *
+ * where @ptr is a pointer to kvfree().
+ *
+ * Please note, head-less way of freeing is permitted to
+ * use from a context that has to follow might_sleep()
+ * annotation. Otherwise, please switch and embed the
+ * rcu_head structure within the type of @ptr.
+ */
+#define kvfree_rcu(...) KVFREE_GET_MACRO(__VA_ARGS__,		\
+	kvfree_rcu_arg_2, kvfree_rcu_arg_1)(__VA_ARGS__)
+
+#define KVFREE_GET_MACRO(_1, _2, NAME, ...) NAME
+#define kvfree_rcu_arg_2(ptr, rhf) kfree_rcu(ptr, rhf)
+#define kvfree_rcu_arg_1(ptr)					\
+do {								\
+	typeof(ptr) ___p = (ptr);				\
+								\
+	if (___p)						\
+		kvfree_call_rcu(NULL, (rcu_callback_t) (___p));	\
+} while (0)
 
 /*
  * Place this after a lock-acquisition primitive to guarantee that
@@ -862,4 +953,49 @@
 #endif /* #else #ifdef CONFIG_ARCH_WEAK_RELEASE_ACQUIRE */
 
 
+/* Has the specified rcu_head structure been handed to call_rcu()? */
+
+/**
+ * rcu_head_init - Initialize rcu_head for rcu_head_after_call_rcu()
+ * @rhp: The rcu_head structure to initialize.
+ *
+ * If you intend to invoke rcu_head_after_call_rcu() to test whether a
+ * given rcu_head structure has already been passed to call_rcu(), then
+ * you must also invoke this rcu_head_init() function on it just after
+ * allocating that structure.  Calls to this function must not race with
+ * calls to call_rcu(), rcu_head_after_call_rcu(), or callback invocation.
+ */
+static inline void rcu_head_init(struct rcu_head *rhp)
+{
+	rhp->func = (rcu_callback_t)~0L;
+}
+
+/**
+ * rcu_head_after_call_rcu() - Has this rcu_head been passed to call_rcu()?
+ * @rhp: The rcu_head structure to test.
+ * @f: The function passed to call_rcu() along with @rhp.
+ *
+ * Returns @true if the @rhp has been passed to call_rcu() with @func,
+ * and @false otherwise.  Emits a warning in any other case, including
+ * the case where @rhp has already been invoked after a grace period.
+ * Calls to this function must not race with callback invocation.  One way
+ * to avoid such races is to enclose the call to rcu_head_after_call_rcu()
+ * in an RCU read-side critical section that includes a read-side fetch
+ * of the pointer to the structure containing @rhp.
+ */
+static inline bool
+rcu_head_after_call_rcu(struct rcu_head *rhp, rcu_callback_t f)
+{
+	rcu_callback_t func = READ_ONCE(rhp->func);
+
+	if (func == f)
+		return true;
+	WARN_ON_ONCE(func != (rcu_callback_t)~0L);
+	return false;
+}
+
+/* kernel/ksysfs.c definitions */
+extern int rcu_expedited;
+extern int rcu_normal;
+
 #endif /* __LINUX_RCUPDATE_H */

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