Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull RCU updates from Ingo Molnar: "The RCU changes in this cycle were: - Expedited grace-period updates - kfree_rcu() updates - RCU list updates - Preemptible RCU updates - Torture-test updates - Miscellaneous fixes - Documentation updates" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (69 commits) rcu: Remove unused stop-machine #include powerpc: Remove comment about read_barrier_depends() .mailmap: Add entries for old paulmck@kernel.org addresses srcu: Apply *_ONCE() to ->srcu_last_gp_end rcu: Switch force_qs_rnp() to for_each_leaf_node_cpu_mask() rcu: Move rcu_{expedited,normal} definitions into rcupdate.h rcu: Move gp_state_names[] and gp_state_getname() to tree_stall.h rcu: Remove the declaration of call_rcu() in tree.h rcu: Fix tracepoint tracking RCU CPU kthread utilization rcu: Fix harmless omission of "CONFIG_" from #if condition rcu: Avoid tick_dep_set_cpu() misordering rcu: Provide wrappers for uses of ->rcu_read_lock_nesting rcu: Use READ_ONCE() for ->expmask in rcu_read_unlock_special() rcu: Clear ->rcu_read_unlock_special only once rcu: Clear .exp_hint only when deferred quiescent state has been reported rcu: Rename some instance of CONFIG_PREEMPTION to CONFIG_PREEMPT_RCU rcu: Remove kfree_call_rcu_nobatch() rcu: Remove kfree_rcu() special casing and lazy-callback handling rcu: Add support for debug_objects debugging for kfree_rcu() rcu: Add multiple in-flight batches of kfree_rcu() work ...

Linus Torvalds committed 6 years ago

Commit d99391e2 parents 8b56177 f8a4bb646 files · +1476 −851Browse files

Showing the changes to include/linux (9 of 46 files). Show all

Unified · Split

9 files

include/linux/list.h +112 −24
include/linux/list_nulls.h +26 −4
include/linux/rcu_segcblist.h +0 −2
include/linux/rculist.h +24 −14
include/linux/rculist_nulls.h +14 −6
include/linux/rcupdate.h +8 −20
include/linux/rcutiny.h +1 −0
include/linux/rcutree.h +1 −0
include/linux/tick.h +4 −1

include/linux/list.h+112−24

 #define LIST_HEAD(name) \
 	struct list_head name = LIST_HEAD_INIT(name)
+/**
+ * INIT_LIST_HEAD - Initialize a list_head structure
+ * @list: list_head structure to be initialized.
+ *
+ * Initializes the list_head to point to itself.  If it is a list header,
+ * the result is an empty list.
+ */
 static inline void INIT_LIST_HEAD(struct list_head *list)
 {
 	WRITE_ONCE(list->next, list);
 	entry->prev = NULL;
 }
-/**
- * list_del - deletes entry from list.
- * @entry: the element to delete from the list.
- * Note: list_empty() on entry does not return true after this, the entry is
- * in an undefined state.
- */
 static inline void __list_del_entry(struct list_head *entry)
 {
 	if (!__list_del_entry_valid(entry))
 	__list_del(entry->prev, entry->next);
 }
+/**
+ * list_del - deletes entry from list.
+ * @entry: the element to delete from the list.
+ * Note: list_empty() on entry does not return true after this, the entry is
+ * in an undefined state.
+ */
 static inline void list_del(struct list_head *entry)
 {
 	__list_del_entry(entry);
 	new->prev->next = new;
 }
+/**
+ * list_replace_init - replace old entry by new one and initialize the old one
+ * @old : the element to be replaced
+ * @new : the new element to insert
+ *
+ * If @old was empty, it will be overwritten.
+ */
 static inline void list_replace_init(struct list_head *old,
-					struct list_head *new)
+				     struct list_head *new)
 {
 	list_replace(old, new);
 	INIT_LIST_HEAD(old);
 	h->pprev = NULL;
 }
+/**
+ * hlist_unhashed - Has node been removed from list and reinitialized?
+ * @h: Node to be checked
+ *
+ * Not that not all removal functions will leave a node in unhashed
+ * state.  For example, hlist_nulls_del_init_rcu() does leave the
+ * node in unhashed state, but hlist_nulls_del() does not.
+ */
 static inline int hlist_unhashed(const struct hlist_node *h)
 {
 	return !h->pprev;
 }
+/**
+ * hlist_unhashed_lockless - Version of hlist_unhashed for lockless use
+ * @h: Node to be checked
+ *
+ * This variant of hlist_unhashed() must be used in lockless contexts
+ * to avoid potential load-tearing.  The READ_ONCE() is paired with the
+ * various WRITE_ONCE() in hlist helpers that are defined below.
+ */
+static inline int hlist_unhashed_lockless(const struct hlist_node *h)
+{
+	return !READ_ONCE(h->pprev);
+}
+/**
+ * hlist_empty - Is the specified hlist_head structure an empty hlist?
+ * @h: Structure to check.
+ */
 static inline int hlist_empty(const struct hlist_head *h)
 {
 	return !READ_ONCE(h->first);
 	WRITE_ONCE(*pprev, next);
 	if (next)
-		next->pprev = pprev;
+		WRITE_ONCE(next->pprev, pprev);
 }
+/**
+ * hlist_del - Delete the specified hlist_node from its list
+ * @n: Node to delete.
+ *
+ * Note that this function leaves the node in hashed state.  Use
+ * hlist_del_init() or similar instead to unhash @n.
+ */
 static inline void hlist_del(struct hlist_node *n)
 {
 	__hlist_del(n);
 	n->pprev = LIST_POISON2;
 }
+/**
+ * hlist_del_init - Delete the specified hlist_node from its list and initialize
+ * @n: Node to delete.
+ *
+ * Note that this function leaves the node in unhashed state.
+ */
 static inline void hlist_del_init(struct hlist_node *n)
 {
 	if (!hlist_unhashed(n)) {
 	}
 }
+/**
+ * hlist_add_head - add a new entry at the beginning of the hlist
+ * @n: new entry to be added
+ * @h: hlist head to add it after
+ *
+ * Insert a new entry after the specified head.
+ * This is good for implementing stacks.
+ */
 static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
 {
 	struct hlist_node *first = h->first;
-	n->next = first;
+	WRITE_ONCE(n->next, first);
 	if (first)
-		first->pprev = &n->next;
+		WRITE_ONCE(first->pprev, &n->next);
 	WRITE_ONCE(h->first, n);
-	n->pprev = &h->first;
+	WRITE_ONCE(n->pprev, &h->first);
 }
-/* next must be != NULL */
+/**
+ * hlist_add_before - add a new entry before the one specified
+ * @n: new entry to be added
+ * @next: hlist node to add it before, which must be non-NULL
+ */
 static inline void hlist_add_before(struct hlist_node *n,
-					struct hlist_node *next)
+				    struct hlist_node *next)
 {
-	n->pprev = next->pprev;
+	WRITE_ONCE(n->pprev, next->pprev);
-	n->next = next;
+	WRITE_ONCE(n->next, next);
-	next->pprev = &n->next;
+	WRITE_ONCE(next->pprev, &n->next);
 	WRITE_ONCE(*(n->pprev), n);
 }
+/**
+ * hlist_add_behing - add a new entry after the one specified
+ * @n: new entry to be added
+ * @prev: hlist node to add it after, which must be non-NULL
+ */
 static inline void hlist_add_behind(struct hlist_node *n,
 				    struct hlist_node *prev)
 {
-	n->next = prev->next;
+	WRITE_ONCE(n->next, prev->next);
-	prev->next = n;
+	WRITE_ONCE(prev->next, n);
-	n->pprev = &prev->next;
+	WRITE_ONCE(n->pprev, &prev->next);
 	if (n->next)
-		n->next->pprev  = &n->next;
+		WRITE_ONCE(n->next->pprev, &n->next);
 }
-/* after that we'll appear to be on some hlist and hlist_del will work */
+/**
+ * hlist_add_fake - create a fake hlist consisting of a single headless node
+ * @n: Node to make a fake list out of
+ *
+ * This makes @n appear to be its own predecessor on a headless hlist.
+ * The point of this is to allow things like hlist_del() to work correctly
+ * in cases where there is no list.
+ */
 static inline void hlist_add_fake(struct hlist_node *n)
 {
 	n->pprev = &n->next;
 }
+/**
+ * hlist_fake: Is this node a fake hlist?
+ * @h: Node to check for being a self-referential fake hlist.
+ */
 static inline bool hlist_fake(struct hlist_node *h)
 {
 	return h->pprev == &h->next;
 }
-/*
+/**
+ * hlist_is_singular_node - is node the only element of the specified hlist?
+ * @n: Node to check for singularity.
+ * @h: Header for potentially singular list.
+ *
  * Check whether the node is the only node of the head without
- * accessing head:
+ * accessing head, thus avoiding unnecessary cache misses.
  */
 static inline bool
 hlist_is_singular_node(struct hlist_node *n, struct hlist_head *h)
 	return !n->next && n->pprev == &h->first;
 }
-/*
+/**
+ * hlist_move_list - Move an hlist
+ * @old: hlist_head for old list.
+ * @new: hlist_head for new list.
+ *
  * Move a list from one list head to another. Fixup the pprev
  * reference of the first entry if it exists.
  */

include/linux/list_nulls.h+26−4

 	return ((unsigned long)ptr) >> 1;
 }
+/**
+ * hlist_nulls_unhashed - Has node been removed and reinitialized?
+ * @h: Node to be checked
+ *
+ * Not that not all removal functions will leave a node in unhashed state.
+ * For example, hlist_del_init_rcu() leaves the node in unhashed state,
+ * but hlist_nulls_del() does not.
+ */
 static inline int hlist_nulls_unhashed(const struct hlist_nulls_node *h)
 {
 	return !h->pprev;
 }
+/**
+ * hlist_nulls_unhashed_lockless - Has node been removed and reinitialized?
+ * @h: Node to be checked
+ *
+ * Not that not all removal functions will leave a node in unhashed state.
+ * For example, hlist_del_init_rcu() leaves the node in unhashed state,
+ * but hlist_nulls_del() does not.  Unlike hlist_nulls_unhashed(), this
+ * function may be used locklessly.
+ */
+static inline int hlist_nulls_unhashed_lockless(const struct hlist_nulls_node *h)
+{
+	return !READ_ONCE(h->pprev);
+}
 static inline int hlist_nulls_empty(const struct hlist_nulls_head *h)
 {
 	return is_a_nulls(READ_ONCE(h->first));
 	struct hlist_nulls_node *first = h->first;
 	n->next = first;
-	n->pprev = &h->first;
+	WRITE_ONCE(n->pprev, &h->first);
 	h->first = n;
 	if (!is_a_nulls(first))
-		first->pprev = &n->next;
+		WRITE_ONCE(first->pprev, &n->next);
 }
 static inline void __hlist_nulls_del(struct hlist_nulls_node *n)
 	WRITE_ONCE(*pprev, next);
 	if (!is_a_nulls(next))
-		next->pprev = pprev;
+		WRITE_ONCE(next->pprev, pprev);
 }
 static inline void hlist_nulls_del(struct hlist_nulls_node *n)
 {
 	__hlist_nulls_del(n);
-	n->pprev = LIST_POISON2;
+	WRITE_ONCE(n->pprev, LIST_POISON2);
 }
 /**

include/linux/rcu_segcblist.h+0−2

 	struct rcu_head *head;
 	struct rcu_head **tail;
 	long len;
-	long len_lazy;
 };
 #define RCU_CBLIST_INITIALIZER(n) { .head = NULL, .tail = &n.head }
 #else
 	long len;
 #endif
-	long len_lazy;
 	u8 enabled;
 	u8 offloaded;
 };

include/linux/rculist.h+24−14

  */
 #define list_next_rcu(list)	(*((struct list_head __rcu **)(&(list)->next)))
+/**
+ * list_tail_rcu - returns the prev pointer of the head of the list
+ * @head: the head of the list
+ *
+ * Note: This should only be used with the list header, and even then
+ * only if list_del() and similar primitives are not also used on the
+ * list header.
+ */
+#define list_tail_rcu(head)	(*((struct list_head __rcu **)(&(head)->prev)))
 /*
  * Check during list traversal that we are within an RCU reader
  */
 {
 	if (!hlist_unhashed(n)) {
 		__hlist_del(n);
-		n->pprev = NULL;
+		WRITE_ONCE(n->pprev, NULL);
 	}
 }
  * @pos:	the type * to use as a loop cursor.
  * @head:	the head for your list.
  * @member:	the name of the list_head within the struct.
- * @cond:	optional lockdep expression if called from non-RCU protection.
+ * @cond...:	optional lockdep expression if called from non-RCU protection.
  *
  * This list-traversal primitive may safely run concurrently with
  * the _rcu list-mutation primitives such as list_add_rcu()
 static inline void hlist_del_rcu(struct hlist_node *n)
 {
 	__hlist_del(n);
-	n->pprev = LIST_POISON2;
+	WRITE_ONCE(n->pprev, LIST_POISON2);
 }
 /**
 	struct hlist_node *next = old->next;
 	new->next = next;
-	new->pprev = old->pprev;
+	WRITE_ONCE(new->pprev, old->pprev);
 	rcu_assign_pointer(*(struct hlist_node __rcu **)new->pprev, new);
 	if (next)
-		new->next->pprev = &new->next;
+		WRITE_ONCE(new->next->pprev, &new->next);
-	old->pprev = LIST_POISON2;
+	WRITE_ONCE(old->pprev, LIST_POISON2);
 }
 /*
 	struct hlist_node *first = h->first;
 	n->next = first;
-	n->pprev = &h->first;
+	WRITE_ONCE(n->pprev, &h->first);
 	rcu_assign_pointer(hlist_first_rcu(h), n);
 	if (first)
-		first->pprev = &n->next;
+		WRITE_ONCE(first->pprev, &n->next);
 }
 /**
 	if (last) {
 		n->next = last->next;
-		n->pprev = &last->next;
+		WRITE_ONCE(n->pprev, &last->next);
 		rcu_assign_pointer(hlist_next_rcu(last), n);
 	} else {
 		hlist_add_head_rcu(n, h);
 static inline void hlist_add_before_rcu(struct hlist_node *n,
 					struct hlist_node *next)
 {
-	n->pprev = next->pprev;
+	WRITE_ONCE(n->pprev, next->pprev);
 	n->next = next;
 	rcu_assign_pointer(hlist_pprev_rcu(n), n);
-	next->pprev = &n->next;
+	WRITE_ONCE(next->pprev, &n->next);
 }
 /**
 					struct hlist_node *prev)
 {
 	n->next = prev->next;
-	n->pprev = &prev->next;
+	WRITE_ONCE(n->pprev, &prev->next);
 	rcu_assign_pointer(hlist_next_rcu(prev), n);
 	if (n->next)
-		n->next->pprev = &n->next;
+		WRITE_ONCE(n->next->pprev, &n->next);
 }
 #define __hlist_for_each_rcu(pos, head)				\
  * @pos:	the type * to use as a loop cursor.
  * @head:	the head for your list.
  * @member:	the name of the hlist_node within the struct.
- * @cond:	optional lockdep expression if called from non-RCU protection.
+ * @cond...:	optional lockdep expression if called from non-RCU protection.
  *
  * This list-traversal primitive may safely run concurrently with
  * the _rcu list-mutation primitives such as hlist_add_head_rcu()

include/linux/rculist_nulls.h+14−6

 {
 	if (!hlist_nulls_unhashed(n)) {
 		__hlist_nulls_del(n);
-		n->pprev = NULL;
+		WRITE_ONCE(n->pprev, NULL);
 	}
 }
+/**
+ * hlist_nulls_first_rcu - returns the first element of the hash list.
+ * @head: the head of the list.
+ */
 #define hlist_nulls_first_rcu(head) \
 	(*((struct hlist_nulls_node __rcu __force **)&(head)->first))
+/**
+ * hlist_nulls_next_rcu - returns the element of the list after @node.
+ * @node: element of the list.
+ */
 #define hlist_nulls_next_rcu(node) \
 	(*((struct hlist_nulls_node __rcu __force **)&(node)->next))
 static inline void hlist_nulls_del_rcu(struct hlist_nulls_node *n)
 {
 	__hlist_nulls_del(n);
-	n->pprev = LIST_POISON2;
+	WRITE_ONCE(n->pprev, LIST_POISON2);
 }
 /**
 	struct hlist_nulls_node *first = h->first;
 	n->next = first;
-	n->pprev = &h->first;
+	WRITE_ONCE(n->pprev, &h->first);
 	rcu_assign_pointer(hlist_nulls_first_rcu(h), n);
 	if (!is_a_nulls(first))
-		first->pprev = &n->next;
+		WRITE_ONCE(first->pprev, &n->next);
 }
 /**
  * hlist_nulls_for_each_entry_rcu - iterate over rcu list of given type
  * @tpos:	the type * to use as a loop cursor.
  * @pos:	the &struct hlist_nulls_node to use as a loop cursor.
- * @head:	the head for your list.
+ * @head:	the head of the list.
  * @member:	the name of the hlist_nulls_node within the struct.
  *
  * The barrier() is needed to make sure compiler doesn't cache first element [1],
  *   iterate over list of given type safe against removal of list entry
  * @tpos:	the type * to use as a loop cursor.
  * @pos:	the &struct hlist_nulls_node to use as a loop cursor.
- * @head:	the head for your list.
+ * @head:	the head of the list.
  * @member:	the name of the hlist_nulls_node within the struct.
  */
 #define hlist_nulls_for_each_entry_safe(tpos, pos, head, member)		\

include/linux/rcupdate.h+8−20

  *
  * 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 { \
  * 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>
 	__tmp;								\
 })
-/**
- * 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.
- */
-#define rcu_swap_protected(rcu_ptr, ptr, c) do {			\
-	typeof(ptr) __tmp = rcu_dereference_protected((rcu_ptr), (c));	\
-	rcu_assign_pointer((rcu_ptr), (ptr));				\
-	(ptr) = __tmp;							\
-} while (0)
 /**
  * rcu_access_pointer() - fetch RCU pointer with no dereferencing
  * @p: The pointer to read
  *
  * 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_PREEMPTION
  * kernel builds, RCU read-side critical sections may be preempted,
 	return false;
 }
+/* kernel/ksysfs.c definitions */
+extern int rcu_expedited;
+extern int rcu_normal;
 #endif /* __LINUX_RCUPDATE_H */

include/linux/rcutiny.h+1−0

@@ -85,6 +85,7 @@ static inline void rcu_scheduler_starting(void) { } · 84 unmodified lines
85	static inline void rcu_end_inkernel_boot(void) { }	85	static inline void rcu_end_inkernel_boot(void) { }
86	static inline bool rcu_is_watching(void) { return true; }	86	static inline bool rcu_is_watching(void) { return true; }
87	static inline void rcu_momentary_dyntick_idle(void) { }	87	static inline void rcu_momentary_dyntick_idle(void) { }
		88	static inline void kfree_rcu_scheduler_running(void) { }
88		89
89	/* Avoid RCU read-side critical sections leaking across. */	90	/* Avoid RCU read-side critical sections leaking across. */
90	static inline void rcu_all_qs(void) { barrier(); }	91	static inline void rcu_all_qs(void) { barrier(); }

include/linux/rcutree.h+1−0

@@ -38,6 +38,7 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func); · 37 unmodified lines
38	void rcu_barrier(void);	38	void rcu_barrier(void);
39	bool rcu_eqs_special_set(int cpu);	39	bool rcu_eqs_special_set(int cpu);
40	void rcu_momentary_dyntick_idle(void);	40	void rcu_momentary_dyntick_idle(void);
		41	void kfree_rcu_scheduler_running(void);
41	unsigned long get_state_synchronize_rcu(void);	42	unsigned long get_state_synchronize_rcu(void);
42	void cond_synchronize_rcu(unsigned long oldstate);	43	void cond_synchronize_rcu(unsigned long oldstate);
43		44

include/linux/tick.h+4−1

 	TICK_DEP_BIT_PERF_EVENTS	= 1,
 	TICK_DEP_BIT_SCHED		= 2,
 	TICK_DEP_BIT_CLOCK_UNSTABLE	= 3,
-	TICK_DEP_BIT_RCU		= 4
+	TICK_DEP_BIT_RCU		= 4,
+	TICK_DEP_BIT_RCU_EXP		= 5
 };
+#define TICK_DEP_BIT_MAX TICK_DEP_BIT_RCU_EXP
 #define TICK_DEP_MASK_NONE		0
 #define TICK_DEP_MASK_POSIX_TIMER	(1 << TICK_DEP_BIT_POSIX_TIMER)
 #define TICK_DEP_MASK_SCHED		(1 << TICK_DEP_BIT_SCHED)
 #define TICK_DEP_MASK_CLOCK_UNSTABLE	(1 << TICK_DEP_BIT_CLOCK_UNSTABLE)
 #define TICK_DEP_MASK_RCU		(1 << TICK_DEP_BIT_RCU)
+#define TICK_DEP_MASK_RCU_EXP		(1 << TICK_DEP_BIT_RCU_EXP)
 #ifdef CONFIG_NO_HZ_COMMON
 extern bool tick_nohz_enabled;