Merge branches 'doc.2015.12.05a', 'exp.2015.12.07a', 'fixes.2015.12.07a',... (648c630c) · Commits · 戴 / test

Documentation/kernel-parameters.txt

+23 −6

Original line number	Diff line number	Diff line
		@@ -3296,18 +3296,35 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
		rcutorture.verbose= [KNL]
		Enable additional printk() statements.

		rcupdate.rcu_cpu_stall_suppress= [KNL]
		Suppress RCU CPU stall warning messages.

		rcupdate.rcu_cpu_stall_timeout= [KNL]
		Set timeout for RCU CPU stall warning messages.

		rcupdate.rcu_expedited= [KNL]
		Use expedited grace-period primitives, for
		example, synchronize_rcu_expedited() instead
		of synchronize_rcu(). This reduces latency,
		but can increase CPU utilization, degrade
		real-time latency, and degrade energy efficiency.

		rcupdate.rcu_cpu_stall_suppress= [KNL]
		Suppress RCU CPU stall warning messages.

		rcupdate.rcu_cpu_stall_timeout= [KNL]
		Set timeout for RCU CPU stall warning messages.
		No effect on CONFIG_TINY_RCU kernels.

		rcupdate.rcu_normal= [KNL]
		Use only normal grace-period primitives,
		for example, synchronize_rcu() instead of
		synchronize_rcu_expedited(). This improves
		real-time latency, CPU utilization, and
		energy efficiency, but can expose users to
		increased grace-period latency. This parameter
		overrides rcupdate.rcu_expedited. No effect on
		CONFIG_TINY_RCU kernels.

		rcupdate.rcu_normal_after_boot= [KNL]
		Once boot has completed (that is, after
		rcu_end_inkernel_boot() has been invoked), use
		only normal grace-period primitives. No effect
		on CONFIG_TINY_RCU kernels.

		rcupdate.rcu_task_stall_timeout= [KNL]
		Set timeout in jiffies for RCU task stall warning

include/linux/list.h

+7 −7

Original line number	Diff line number	Diff line
		@@ -24,7 +24,7 @@

		static inline void INIT_LIST_HEAD(struct list_head *list)
		{
		list->next = list;
		WRITE_ONCE(list->next, list);
		list->prev = list;
		}

		@@ -42,7 +42,7 @@ static inline void __list_add(struct list_head *new,
		next->prev = new;
		new->next = next;
		new->prev = prev;
		prev->next = new;
		WRITE_ONCE(prev->next, new);
		}
		#else
		extern void __list_add(struct list_head *new,
		@@ -186,7 +186,7 @@ static inline int list_is_last(const struct list_head *list,
		*/
		static inline int list_empty(const struct list_head *head)
		{
		return head->next == head;
		return READ_ONCE(head->next) == head;
		}

		/**
		@@ -608,7 +608,7 @@ static inline int hlist_unhashed(const struct hlist_node *h)

		static inline int hlist_empty(const struct hlist_head *h)
		{
		return !h->first;
		return !READ_ONCE(h->first);
		}

		static inline void __hlist_del(struct hlist_node *n)
		@@ -642,7 +642,7 @@ static inline void hlist_add_head(struct hlist_node n, struct hlist_head h)
		n->next = first;
		if (first)
		first->pprev = &n->next;
		h->first = n;
		WRITE_ONCE(h->first, n);
		n->pprev = &h->first;
		}

		@@ -653,14 +653,14 @@ static inline void hlist_add_before(struct hlist_node *n,
		n->pprev = next->pprev;
		n->next = next;
		next->pprev = &n->next;
		*(n->pprev) = n;
		WRITE_ONCE(*(n->pprev), n);
		}

		static inline void hlist_add_behind(struct hlist_node *n,
		struct hlist_node *prev)
		{
		n->next = prev->next;
		prev->next = n;
		WRITE_ONCE(prev->next, n);
		n->pprev = &prev->next;

		if (n->next)

include/linux/list_bl.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -70,7 +70,7 @@ static inline void hlist_bl_set_first(struct hlist_bl_head *h,

		static inline int hlist_bl_empty(const struct hlist_bl_head *h)
		{
		return !((unsigned long)h->first & ~LIST_BL_LOCKMASK);
		return !((unsigned long)READ_ONCE(h->first) & ~LIST_BL_LOCKMASK);
		}

		static inline void hlist_bl_add_head(struct hlist_bl_node *n,

include/linux/list_nulls.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -57,7 +57,7 @@ static inline int hlist_nulls_unhashed(const struct hlist_nulls_node *h)

		static inline int hlist_nulls_empty(const struct hlist_nulls_head *h)
		{
		return is_a_nulls(h->first);
		return is_a_nulls(READ_ONCE(h->first));
		}

		static inline void hlist_nulls_add_head(struct hlist_nulls_node *n,

include/linux/rculist.h

+85 −20

Original line number	Diff line number	Diff line
		@@ -179,32 +179,31 @@ static inline void list_replace_rcu(struct list_head *old,
		}

		/**
		* list_splice_init_rcu - splice an RCU-protected list into an existing list.
		* __list_splice_init_rcu - join an RCU-protected list into an existing list.
		* @list: the RCU-protected list to splice
		* @head: the place in the list to splice the first list into
		* @prev: points to the last element of the existing list
		* @next: points to the first element of the existing list
		* @sync: function to sync: synchronize_rcu(), synchronize_sched(), ...
		*
		* @head can be RCU-read traversed concurrently with this function.
		* The list pointed to by @prev and @next can be RCU-read traversed
		* concurrently with this function.
		*
		* Note that this function blocks.
		*
		* Important note: the caller must take whatever action is necessary to
		* prevent any other updates to @head. In principle, it is possible
		* to modify the list as soon as sync() begins execution.
		* If this sort of thing becomes necessary, an alternative version
		* based on call_rcu() could be created. But only if -really-
		* needed -- there is no shortage of RCU API members.
		* Important note: the caller must take whatever action is necessary to prevent
		* any other updates to the existing list. In principle, it is possible to
		* modify the list as soon as sync() begins execution. If this sort of thing
		* becomes necessary, an alternative version based on call_rcu() could be
		* created. But only if -really- needed -- there is no shortage of RCU API
		* members.
		*/
		static inline void list_splice_init_rcu(struct list_head *list,
		struct list_head *head,
		static inline void __list_splice_init_rcu(struct list_head *list,
		struct list_head *prev,
		struct list_head *next,
		void (*sync)(void))
		{
		struct list_head *first = list->next;
		struct list_head *last = list->prev;
		struct list_head *at = head->next;

		if (list_empty(list))
		return;

		/*
		* "first" and "last" tracking list, so initialize it. RCU readers
		@@ -231,10 +230,40 @@ static inline void list_splice_init_rcu(struct list_head *list,
		* this function.
		*/

		last->next = at;
		rcu_assign_pointer(list_next_rcu(head), first);
		first->prev = head;
		at->prev = last;
		last->next = next;
		rcu_assign_pointer(list_next_rcu(prev), first);
		first->prev = prev;
		next->prev = last;
		}

		/**
		* list_splice_init_rcu - splice an RCU-protected list into an existing list,
		* designed for stacks.
		* @list: the RCU-protected list to splice
		* @head: the place in the existing list to splice the first list into
		* @sync: function to sync: synchronize_rcu(), synchronize_sched(), ...
		*/
		static inline void list_splice_init_rcu(struct list_head *list,
		struct list_head *head,
		void (*sync)(void))
		{
		if (!list_empty(list))
		__list_splice_init_rcu(list, head, head->next, sync);
		}

		/**
		* list_splice_tail_init_rcu - splice an RCU-protected list into an existing
		* list, designed for queues.
		* @list: the RCU-protected list to splice
		* @head: the place in the existing list to splice the first list into
		* @sync: function to sync: synchronize_rcu(), synchronize_sched(), ...
		*/
		static inline void list_splice_tail_init_rcu(struct list_head *list,
		struct list_head *head,
		void (*sync)(void))
		{
		if (!list_empty(list))
		__list_splice_init_rcu(list, head->prev, head, sync);
		}

		/**
		@@ -304,6 +333,42 @@ static inline void list_splice_init_rcu(struct list_head *list,
		&pos->member != (head); \
		pos = list_entry_rcu(pos->member.next, typeof(*pos), member))

		/**
		* list_entry_lockless - get the struct for this entry
		* @ptr: the &struct list_head pointer.
		* @type: the type of the struct this is embedded in.
		* @member: the name of the list_head within the struct.
		*
		* This primitive may safely run concurrently with the _rcu list-mutation
		* primitives such as list_add_rcu(), but requires some implicit RCU
		* read-side guarding. One example is running within a special
		* exception-time environment where preemption is disabled and where
		* lockdep cannot be invoked (in which case updaters must use RCU-sched,
		* as in synchronize_sched(), call_rcu_sched(), and friends). Another
		* example is when items are added to the list, but never deleted.
		*/
		#define list_entry_lockless(ptr, type, member) \
		container_of((typeof(ptr))lockless_dereference(ptr), type, member)

		/**
		* list_for_each_entry_lockless - iterate over rcu list of given type
		* @pos: the type * to use as a loop cursor.
		* @head: the head for your list.
		* @member: the name of the list_struct within the struct.
		*
		* This primitive may safely run concurrently with the _rcu list-mutation
		* primitives such as list_add_rcu(), but requires some implicit RCU
		* read-side guarding. One example is running within a special
		* exception-time environment where preemption is disabled and where
		* lockdep cannot be invoked (in which case updaters must use RCU-sched,
		* as in synchronize_sched(), call_rcu_sched(), and friends). Another
		* example is when items are added to the list, but never deleted.
		*/
		#define list_for_each_entry_lockless(pos, head, member) \
		for (pos = list_entry_lockless((head)->next, typeof(*pos), member); \
		&pos->member != (head); \
		pos = list_entry_lockless(pos->member.next, typeof(*pos), member))

		/**
		* list_for_each_entry_continue_rcu - continue iteration over list of given type
		* @pos: the type * to use as a loop cursor.

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