---

yaml
---
r: 338806
b: refs/heads/master
c: 4e87b2d
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 351573a86d0ef17cbba1c5436706602692781bfe
+refs/heads/master: 4e87b2d7e887df3fe251dd7f702591a3acf369ca

trunk/Documentation/RCU/checklist.txt

@@ -271,14 +271,15 @@ over a rather long period of time, but improvements are always welcome!
 	The same cautions apply to call_rcu_bh() and call_rcu_sched().
 
 9.	All RCU list-traversal primitives, which include
-	rcu_dereference(), list_for_each_entry_rcu(), and
-	list_for_each_safe_rcu(), must be either within an RCU read-side
-	critical section or must be protected by appropriate update-side
-	locks.	RCU read-side critical sections are delimited by
-	rcu_read_lock() and rcu_read_unlock(), or by similar primitives
-	such as rcu_read_lock_bh() and rcu_read_unlock_bh(), in which
-	case the matching rcu_dereference() primitive must be used in
-	order to keep lockdep happy, in this case, rcu_dereference_bh().
+	rcu_dereference(), list_for_each_entry_rcu(),
+	list_for_each_continue_rcu(), and list_for_each_safe_rcu(),
+	must be either within an RCU read-side critical section or
+	must be protected by appropriate update-side locks.  RCU
+	read-side critical sections are delimited by rcu_read_lock()
+	and rcu_read_unlock(), or by similar primitives such as
+	rcu_read_lock_bh() and rcu_read_unlock_bh(), in which case
+	the matching rcu_dereference() primitive must be used in order
+	to keep lockdep happy, in this case, rcu_dereference_bh().
 
 	The reason that it is permissible to use RCU list-traversal
 	primitives when the update-side lock is held is that doing so

trunk/Documentation/RCU/whatisRCU.txt

@@ -789,7 +789,9 @@ RCU list traversal:
 	list_for_each_entry_rcu
 	hlist_for_each_entry_rcu
 	hlist_nulls_for_each_entry_rcu
-	list_for_each_entry_continue_rcu
+
+	list_for_each_continue_rcu	(to be deprecated in favor of new
+					 list_for_each_entry_continue_rcu)
 
 RCU pointer/list update:
 

trunk/include/linux/rculist.h

@@ -286,6 +286,23 @@ 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_for_each_continue_rcu
+ * @pos:	the &struct list_head to use as a loop cursor.
+ * @head:	the head for your list.
+ *
+ * Iterate over an rcu-protected list, continuing after current point.
+ *
+ * This list-traversal primitive may safely run concurrently with
+ * the _rcu list-mutation primitives such as list_add_rcu()
+ * as long as the traversal is guarded by rcu_read_lock().
+ */
+#define list_for_each_continue_rcu(pos, head) \
+	for ((pos) = rcu_dereference_raw(list_next_rcu(pos)); \
+		(pos) != (head); \
+		(pos) = rcu_dereference_raw(list_next_rcu(pos)))
+
 /**
  * list_for_each_entry_continue_rcu - continue iteration over list of given type
  * @pos:	the type * to use as a loop cursor.

trunk/include/linux/rcupdate.h

@@ -90,25 +90,6 @@ extern void do_trace_rcu_torture_read(char *rcutorturename,
  * that started after call_rcu() was invoked.  RCU read-side critical
  * sections are delimited by rcu_read_lock() and rcu_read_unlock(),
  * and may be nested.
- *
- * Note that all CPUs must agree that the grace period extended beyond
- * all pre-existing RCU read-side critical section.  On systems with more
- * than one CPU, this means that when "func()" is invoked, each CPU is
- * guaranteed to have executed a full memory barrier since the end of its
- * last RCU read-side critical section whose beginning preceded the call
- * to call_rcu().  It also means that each CPU executing an RCU read-side
- * critical section that continues beyond the start of "func()" must have
- * executed a memory barrier after the call_rcu() but before the beginning
- * of that RCU read-side critical section.  Note that these guarantees
- * include CPUs that are offline, idle, or executing in user mode, as
- * well as CPUs that are executing in the kernel.
- *
- * Furthermore, if CPU A invoked call_rcu() and CPU B invoked the
- * resulting RCU callback function "func()", then both CPU A and CPU B are
- * guaranteed to execute a full memory barrier during the time interval
- * between the call to call_rcu() and the invocation of "func()" -- even
- * if CPU A and CPU B are the same CPU (but again only if the system has
- * more than one CPU).
  */
 extern void call_rcu(struct rcu_head *head,
 			      void (*func)(struct rcu_head *head));
@@ -137,9 +118,6 @@ extern void call_rcu(struct rcu_head *head,
  *  OR
  *  - rcu_read_lock_bh() and rcu_read_unlock_bh(), if in process context.
  *  These may be nested.
- *
- * See the description of call_rcu() for more detailed information on
- * memory ordering guarantees.
  */
 extern void call_rcu_bh(struct rcu_head *head,
 			void (*func)(struct rcu_head *head));
@@ -159,9 +137,6 @@ extern void call_rcu_bh(struct rcu_head *head,
  *  OR
  *  anything that disables preemption.
  *  These may be nested.
- *
- * See the description of call_rcu() for more detailed information on
- * memory ordering guarantees.
  */
 extern void call_rcu_sched(struct rcu_head *head,
 			   void (*func)(struct rcu_head *rcu));

trunk/include/linux/srcu.h

@@ -16,8 +16,10 @@
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  *
  * Copyright (C) IBM Corporation, 2006
+ * Copyright (C) Fujitsu, 2012
  *
  * Author: Paul McKenney <paulmck@us.ibm.com>
+ *	   Lai Jiangshan <laijs@cn.fujitsu.com>
  *
  * For detailed explanation of Read-Copy Update mechanism see -
  * 		Documentation/RCU/ *.txt

trunk/kernel/rcutiny.c

@@ -195,7 +195,7 @@ EXPORT_SYMBOL(rcu_is_cpu_idle);
  */
 int rcu_is_cpu_rrupt_from_idle(void)
 {
-	return rcu_dynticks_nesting <= 1;
+	return rcu_dynticks_nesting <= 0;
 }
 
 /*

trunk/kernel/rcutorture.c

@@ -1396,16 +1396,12 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
 		 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
 		 "test_boost=%d/%d test_boost_interval=%d "
 		 "test_boost_duration=%d shutdown_secs=%d "
-		 "stall_cpu=%d stall_cpu_holdoff=%d "
-		 "n_barrier_cbs=%d "
 		 "onoff_interval=%d onoff_holdoff=%d\n",
 		 torture_type, tag, nrealreaders, nfakewriters,
 		 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
 		 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
 		 test_boost, cur_ops->can_boost,
 		 test_boost_interval, test_boost_duration, shutdown_secs,
-		 stall_cpu, stall_cpu_holdoff,
-		 n_barrier_cbs,
 		 onoff_interval, onoff_holdoff);
 }
 

trunk/kernel/rcutree.c

@@ -212,13 +212,13 @@ DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = {
 #endif
 };
 
-static long blimit = 10;	/* Maximum callbacks per rcu_do_batch. */
-static long qhimark = 10000;	/* If this many pending, ignore blimit. */
-static long qlowmark = 100;	/* Once only this many pending, use blimit. */
+static int blimit = 10;		/* Maximum callbacks per rcu_do_batch. */
+static int qhimark = 10000;	/* If this many pending, ignore blimit. */
+static int qlowmark = 100;	/* Once only this many pending, use blimit. */
 
-module_param(blimit, long, 0444);
-module_param(qhimark, long, 0444);
-module_param(qlowmark, long, 0444);
+module_param(blimit, int, 0444);
+module_param(qhimark, int, 0444);
+module_param(qlowmark, int, 0444);
 
 int rcu_cpu_stall_suppress __read_mostly; /* 1 = suppress stall warnings. */
 int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT;
@@ -1404,37 +1404,15 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
 	    !cpu_needs_another_gp(rsp, rdp)) {
 		/*
 		 * Either we have not yet spawned the grace-period
-		 * task, this CPU does not need another grace period,
-		 * or a grace period is already in progress.
+		 * task or this CPU does not need another grace period.
 		 * Either way, don't start a new grace period.
 		 */
 		raw_spin_unlock_irqrestore(&rnp->lock, flags);
 		return;
 	}
 
-	/*
-	 * Because there is no grace period in progress right now,
-	 * any callbacks we have up to this point will be satisfied
-	 * by the next grace period.  So promote all callbacks to be
-	 * handled after the end of the next grace period.  If the
-	 * CPU is not yet aware of the end of the previous grace period,
-	 * we need to allow for the callback advancement that will
-	 * occur when it does become aware.  Deadlock prevents us from
-	 * making it aware at this point: We cannot acquire a leaf
-	 * rcu_node ->lock while holding the root rcu_node ->lock.
-	 */
-	rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
-	if (rdp->completed == rsp->completed)
-		rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
-
 	rsp->gp_flags = RCU_GP_FLAG_INIT;
-	raw_spin_unlock(&rnp->lock); /* Interrupts remain disabled. */
-
-	/* Ensure that CPU is aware of completion of last grace period. */
-	rcu_process_gp_end(rsp, rdp);
-	local_irq_restore(flags);
-
-	/* Wake up rcu_gp_kthread() to start the grace period. */
+	raw_spin_unlock_irqrestore(&rnp->lock, flags);
 	wake_up(&rsp->gp_wq);
 }
 
@@ -1791,8 +1769,7 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
 {
 	unsigned long flags;
 	struct rcu_head *next, *list, **tail;
-	long bl, count, count_lazy;
-	int i;
+	int bl, count, count_lazy, i;
 
 	/* If no callbacks are ready, just return.*/
 	if (!cpu_has_callbacks_ready_to_invoke(rdp)) {
@@ -2228,28 +2205,10 @@ static inline int rcu_blocking_is_gp(void)
  * rcu_read_lock_sched().
  *
  * This means that all preempt_disable code sequences, including NMI and
- * non-threaded hardware-interrupt handlers, in progress on entry will
- * have completed before this primitive returns.  However, this does not
- * guarantee that softirq handlers will have completed, since in some
- * kernels, these handlers can run in process context, and can block.
- *
- * Note that this guarantee implies further memory-ordering guarantees.
- * On systems with more than one CPU, when synchronize_sched() returns,
- * each CPU is guaranteed to have executed a full memory barrier since the
- * end of its last RCU-sched read-side critical section whose beginning
- * preceded the call to synchronize_sched().  In addition, each CPU having
- * an RCU read-side critical section that extends beyond the return from
- * synchronize_sched() is guaranteed to have executed a full memory barrier
- * after the beginning of synchronize_sched() and before the beginning of
- * that RCU read-side critical section.  Note that these guarantees include
- * CPUs that are offline, idle, or executing in user mode, as well as CPUs
- * that are executing in the kernel.
- *
- * Furthermore, if CPU A invoked synchronize_sched(), which returned
- * to its caller on CPU B, then both CPU A and CPU B are guaranteed
- * to have executed a full memory barrier during the execution of
- * synchronize_sched() -- even if CPU A and CPU B are the same CPU (but
- * again only if the system has more than one CPU).
+ * hardware-interrupt handlers, in progress on entry will have completed
+ * before this primitive returns.  However, this does not guarantee that
+ * softirq handlers will have completed, since in some kernels, these
+ * handlers can run in process context, and can block.
  *
  * This primitive provides the guarantees made by the (now removed)
  * synchronize_kernel() API.  In contrast, synchronize_rcu() only
@@ -2277,9 +2236,6 @@ EXPORT_SYMBOL_GPL(synchronize_sched);
  * read-side critical sections have completed.  RCU read-side critical
  * sections are delimited by rcu_read_lock_bh() and rcu_read_unlock_bh(),
  * and may be nested.
- *
- * See the description of synchronize_sched() for more detailed information
- * on memory ordering guarantees.
  */
 void synchronize_rcu_bh(void)
 {

trunk/kernel/rcutree_plugin.h

@@ -670,9 +670,6 @@ EXPORT_SYMBOL_GPL(kfree_call_rcu);
  * concurrently with new RCU read-side critical sections that began while
  * synchronize_rcu() was waiting.  RCU read-side critical sections are
  * delimited by rcu_read_lock() and rcu_read_unlock(), and may be nested.
- *
- * See the description of synchronize_sched() for more detailed information
- * on memory ordering guarantees.
  */
 void synchronize_rcu(void)
 {
@@ -878,11 +875,6 @@ EXPORT_SYMBOL_GPL(synchronize_rcu_expedited);
 
 /**
  * rcu_barrier - Wait until all in-flight call_rcu() callbacks complete.
- *
- * Note that this primitive does not necessarily wait for an RCU grace period
- * to complete.  For example, if there are no RCU callbacks queued anywhere
- * in the system, then rcu_barrier() is within its rights to return
- * immediately, without waiting for anything, much less an RCU grace period.
  */
 void rcu_barrier(void)
 {

trunk/kernel/srcu.c

@@ -16,8 +16,10 @@
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  *
  * Copyright (C) IBM Corporation, 2006
+ * Copyright (C) Fujitsu, 2012
  *
  * Author: Paul McKenney <paulmck@us.ibm.com>
+ *	   Lai Jiangshan <laijs@cn.fujitsu.com>
  *
  * For detailed explanation of Read-Copy Update mechanism see -
  * 		Documentation/RCU/ *.txt