Merge branches 'doc.2017.01.15b', 'dyntick.2017.01.23a', 'fixes.2017.01.23a',... (31945aa9) · Commits · e / devices / android_kernel_fairphone_FP4

Documentation/RCU/trace.txt

+1 −4

Original line number	Diff line number	Diff line
		@@ -237,7 +237,7 @@ o "ktl" is the low-order 16 bits (in hexadecimal) of the count of

		The output of "cat rcu/rcu_preempt/rcuexp" looks as follows:

		s=21872 wd1=0 wd2=0 wd3=5 n=0 enq=0 sc=21872
		s=21872 wd1=0 wd2=0 wd3=5 enq=0 sc=21872

		These fields are as follows:

		@@ -249,9 +249,6 @@ o "wd1", "wd2", and "wd3" are the number of times that an attempt
		completed an expedited grace period that satisfies the attempted
		request. "Our work is done."

		o "n" is number of times that a concurrent CPU-hotplug operation
		forced a fallback to a normal grace period.

		o "enq" is the number of quiescent states still outstanding.

		o "sc" is the number of times that the attempt to start a

include/linux/llist.h

+21 −16

Original line number	Diff line number	Diff line
		@@ -3,28 +3,33 @@
		/*
		* Lock-less NULL terminated single linked list
		*
		* If there are multiple producers and multiple consumers, llist_add
		* can be used in producers and llist_del_all can be used in
		* consumers. They can work simultaneously without lock. But
		* llist_del_first can not be used here. Because llist_del_first
		* depends on list->first->next does not changed if list->first is not
		* changed during its operation, but llist_del_first, llist_add,
		* llist_add (or llist_del_all, llist_add, llist_add) sequence in
		* another consumer may violate that.
		*
		* If there are multiple producers and one consumer, llist_add can be
		* used in producers and llist_del_all or llist_del_first can be used
		* in the consumer.
		*
		* This can be summarized as follow:
		* Cases where locking is not needed:
		* If there are multiple producers and multiple consumers, llist_add can be
		* used in producers and llist_del_all can be used in consumers simultaneously
		* without locking. Also a single consumer can use llist_del_first while
		* multiple producers simultaneously use llist_add, without any locking.
		*
		* Cases where locking is needed:
		* If we have multiple consumers with llist_del_first used in one consumer, and
		* llist_del_first or llist_del_all used in other consumers, then a lock is
		* needed. This is because llist_del_first depends on list->first->next not
		* changing, but without lock protection, there's no way to be sure about that
		* if a preemption happens in the middle of the delete operation and on being
		* preempted back, the list->first is the same as before causing the cmpxchg in
		* llist_del_first to succeed. For example, while a llist_del_first operation
		* is in progress in one consumer, then a llist_del_first, llist_add,
		* llist_add (or llist_del_all, llist_add, llist_add) sequence in another
		* consumer may cause violations.
		*
		* This can be summarized as follows:
		*
		* \| add \| del_first \| del_all
		* add \| - \| - \| -
		* del_first \| \| L \| L
		* del_all \| \| \| -
		*
		* Where "-" stands for no lock is needed, while "L" stands for lock
		* is needed.
		* Where, a particular row's operation can happen concurrently with a column's
		* operation, with "-" being no lock needed, while "L" being lock is needed.
		*
		* The list entries deleted via llist_del_all can be traversed with
		* traversing function such as llist_for_each etc. But the list

include/linux/rcupdate.h

+12 −0

Original line number	Diff line number	Diff line
		@@ -1161,5 +1161,17 @@ do { \
		ftrace_dump(oops_dump_mode); \
		} while (0)

		/*
		* Place this after a lock-acquisition primitive to guarantee that
		* an UNLOCK+LOCK pair acts as a full barrier. This guarantee applies
		* if the UNLOCK and LOCK are executed by the same CPU or if the
		* UNLOCK and LOCK operate on the same lock variable.
		*/
		#ifdef CONFIG_PPC
		#define smp_mb__after_unlock_lock() smp_mb() /* Full ordering for lock. */
		#else /* #ifdef CONFIG_PPC */
		#define smp_mb__after_unlock_lock() do { } while (0)
		#endif /* #else #ifdef CONFIG_PPC */


		#endif /* __LINUX_RCUPDATE_H */

include/linux/rcutiny.h

+6 −0

Original line number	Diff line number	Diff line
		@@ -27,6 +27,12 @@

		#include <linux/cache.h>

		struct rcu_dynticks;
		static inline int rcu_dynticks_snap(struct rcu_dynticks *rdtp)
		{
		return 0;
		}

		static inline unsigned long get_state_synchronize_rcu(void)
		{
		return 0;

include/linux/srcu.h

+5 −5

Original line number	Diff line number	Diff line
		@@ -33,9 +33,9 @@
		#include <linux/rcupdate.h>
		#include <linux/workqueue.h>

		struct srcu_struct_array {
		unsigned long c[2];
		unsigned long seq[2];
		struct srcu_array {
		unsigned long lock_count[2];
		unsigned long unlock_count[2];
		};

		struct rcu_batch {
		@@ -46,7 +46,7 @@ struct rcu_batch {

		struct srcu_struct {
		unsigned long completed;
		struct srcu_struct_array __percpu *per_cpu_ref;
		struct srcu_array __percpu *per_cpu_ref;
		spinlock_t queue_lock; /* protect ->batch_queue, ->running */
		bool running;
		/* callbacks just queued */
		@@ -118,7 +118,7 @@ void process_srcu(struct work_struct *work);
		* See include/linux/percpu-defs.h for the rules on per-CPU variables.
		*/
		#define __DEFINE_SRCU(name, is_static) \
		static DEFINE_PER_CPU(struct srcu_struct_array, name##_srcu_array);\
		static DEFINE_PER_CPU(struct srcu_array, name##_srcu_array);\
		is_static struct srcu_struct name = __SRCU_STRUCT_INIT(name)
		#define DEFINE_SRCU(name) __DEFINE_SRCU(name, /* not static */)
		#define DEFINE_STATIC_SRCU(name) __DEFINE_SRCU(name, static)