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authorLinus Torvalds <torvalds@linux-foundation.org>2012-12-11 18:10:49 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-12-11 18:10:49 -0800
commit37ea95a959d4a49846ecbf2dd45326b6b34bf049 (patch)
tree43791e1244ce06d8ca18ecbfd0b0f6dcb86ebb8b /include
parentde0c276b31538fcd56611132f20b63eae2891876 (diff)
parent630e1e0bcddfda9566462d4f9a0d58b31c29d467 (diff)
Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU update from Ingo Molnar: "The major features of this tree are: 1. A first version of no-callbacks CPUs. This version prohibits offlining CPU 0, but only when enabled via CONFIG_RCU_NOCB_CPU=y. Relaxing this constraint is in progress, but not yet ready for prime time. These commits were posted to LKML at https://lkml.org/lkml/2012/10/30/724. 2. Changes to SRCU that allows statically initialized srcu_struct structures. These commits were posted to LKML at https://lkml.org/lkml/2012/10/30/296. 3. Restructuring of RCU's debugfs output. These commits were posted to LKML at https://lkml.org/lkml/2012/10/30/341. 4. Additional CPU-hotplug/RCU improvements, posted to LKML at https://lkml.org/lkml/2012/10/30/327. Note that the commit eliminating __stop_machine() was judged to be too-high of risk, so is deferred to 3.9. 5. Changes to RCU's idle interface, most notably a new module parameter that redirects normal grace-period operations to their expedited equivalents. These were posted to LKML at https://lkml.org/lkml/2012/10/30/739. 6. Additional diagnostics for RCU's CPU stall warning facility, posted to LKML at https://lkml.org/lkml/2012/10/30/315. The most notable change reduces the default RCU CPU stall-warning time from 60 seconds to 21 seconds, so that it once again happens sooner than the softlockup timeout. 7. Documentation updates, which were posted to LKML at https://lkml.org/lkml/2012/10/30/280. A couple of late-breaking changes were posted at https://lkml.org/lkml/2012/11/16/634 and https://lkml.org/lkml/2012/11/16/547. 8. Miscellaneous fixes, which were posted to LKML at https://lkml.org/lkml/2012/10/30/309. 9. Finally, a fix for an lockdep-RCU splat was posted to LKML at https://lkml.org/lkml/2012/11/7/486." * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (49 commits) context_tracking: New context tracking susbsystem sched: Mark RCU reader in sched_show_task() rcu: Separate accounting of callbacks from callback-free CPUs rcu: Add callback-free CPUs rcu: Add documentation for the new rcuexp debugfs trace file rcu: Update documentation for TREE_RCU debugfs tracing rcu: Reduce default RCU CPU stall warning timeout rcu: Fix TINY_RCU rcu_is_cpu_rrupt_from_idle check rcu: Clarify memory-ordering properties of grace-period primitives rcu: Add new rcutorture module parameters to start/end test messages rcu: Remove list_for_each_continue_rcu() rcu: Fix batch-limit size problem rcu: Add tracing for synchronize_sched_expedited() rcu: Remove old debugfs interfaces and also RCU flavor name rcu: split 'rcuhier' to each flavor rcu: split 'rcugp' to each flavor rcu: split 'rcuboost' to each flavor rcu: split 'rcubarrier' to each flavor rcu: Fix tracing formatting rcu: Remove the interface "rcudata.csv" ...
Diffstat (limited to 'include')
-rw-r--r--include/linux/context_tracking.h18
-rw-r--r--include/linux/rculist.h17
-rw-r--r--include/linux/rcupdate.h29
-rw-r--r--include/linux/sched.h10
-rw-r--r--include/linux/srcu.h34
-rw-r--r--include/trace/events/rcu.h1
6 files changed, 82 insertions, 27 deletions
diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
new file mode 100644
index 00000000000..e24339ccb7f
--- /dev/null
+++ b/include/linux/context_tracking.h
@@ -0,0 +1,18 @@
+#ifndef _LINUX_CONTEXT_TRACKING_H
+#define _LINUX_CONTEXT_TRACKING_H
+
+#ifdef CONFIG_CONTEXT_TRACKING
+#include <linux/sched.h>
+
+extern void user_enter(void);
+extern void user_exit(void);
+extern void context_tracking_task_switch(struct task_struct *prev,
+ struct task_struct *next);
+#else
+static inline void user_enter(void) { }
+static inline void user_exit(void) { }
+static inline void context_tracking_task_switch(struct task_struct *prev,
+ struct task_struct *next) { }
+#endif /* !CONFIG_CONTEXT_TRACKING */
+
+#endif
diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index e0f0fab2041..c92dd28eaa6 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -286,23 +286,6 @@ 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.
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 7c968e4f929..275aa3f1062 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -90,6 +90,25 @@ 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));
@@ -118,6 +137,9 @@ 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));
@@ -137,6 +159,9 @@ 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));
@@ -197,13 +222,13 @@ extern void rcu_user_enter(void);
extern void rcu_user_exit(void);
extern void rcu_user_enter_after_irq(void);
extern void rcu_user_exit_after_irq(void);
-extern void rcu_user_hooks_switch(struct task_struct *prev,
- struct task_struct *next);
#else
static inline void rcu_user_enter(void) { }
static inline void rcu_user_exit(void) { }
static inline void rcu_user_enter_after_irq(void) { }
static inline void rcu_user_exit_after_irq(void) { }
+static inline void rcu_user_hooks_switch(struct task_struct *prev,
+ struct task_struct *next) { }
#endif /* CONFIG_RCU_USER_QS */
extern void exit_rcu(void);
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 3e387df065f..29116b853ec 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -109,6 +109,8 @@ extern void update_cpu_load_nohz(void);
extern unsigned long get_parent_ip(unsigned long addr);
+extern void dump_cpu_task(int cpu);
+
struct seq_file;
struct cfs_rq;
struct task_group;
@@ -1845,14 +1847,6 @@ static inline void rcu_copy_process(struct task_struct *p)
#endif
-static inline void rcu_switch(struct task_struct *prev,
- struct task_struct *next)
-{
-#ifdef CONFIG_RCU_USER_QS
- rcu_user_hooks_switch(prev, next);
-#endif
-}
-
static inline void tsk_restore_flags(struct task_struct *task,
unsigned long orig_flags, unsigned long flags)
{
diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index 55a5c52cbb2..6eb691b0835 100644
--- a/include/linux/srcu.h
+++ b/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
@@ -40,6 +42,8 @@ struct rcu_batch {
struct rcu_head *head, **tail;
};
+#define RCU_BATCH_INIT(name) { NULL, &(name.head) }
+
struct srcu_struct {
unsigned completed;
struct srcu_struct_array __percpu *per_cpu_ref;
@@ -70,12 +74,42 @@ int __init_srcu_struct(struct srcu_struct *sp, const char *name,
__init_srcu_struct((sp), #sp, &__srcu_key); \
})
+#define __SRCU_DEP_MAP_INIT(srcu_name) .dep_map = { .name = #srcu_name },
#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
int init_srcu_struct(struct srcu_struct *sp);
+#define __SRCU_DEP_MAP_INIT(srcu_name)
#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
+void process_srcu(struct work_struct *work);
+
+#define __SRCU_STRUCT_INIT(name) \
+ { \
+ .completed = -300, \
+ .per_cpu_ref = &name##_srcu_array, \
+ .queue_lock = __SPIN_LOCK_UNLOCKED(name.queue_lock), \
+ .running = false, \
+ .batch_queue = RCU_BATCH_INIT(name.batch_queue), \
+ .batch_check0 = RCU_BATCH_INIT(name.batch_check0), \
+ .batch_check1 = RCU_BATCH_INIT(name.batch_check1), \
+ .batch_done = RCU_BATCH_INIT(name.batch_done), \
+ .work = __DELAYED_WORK_INITIALIZER(name.work, process_srcu, 0),\
+ __SRCU_DEP_MAP_INIT(name) \
+ }
+
+/*
+ * define and init a srcu struct at build time.
+ * dont't call init_srcu_struct() nor cleanup_srcu_struct() on it.
+ */
+#define DEFINE_SRCU(name) \
+ static DEFINE_PER_CPU(struct srcu_struct_array, name##_srcu_array);\
+ struct srcu_struct name = __SRCU_STRUCT_INIT(name);
+
+#define DEFINE_STATIC_SRCU(name) \
+ static DEFINE_PER_CPU(struct srcu_struct_array, name##_srcu_array);\
+ static struct srcu_struct name = __SRCU_STRUCT_INIT(name);
+
/**
* call_srcu() - Queue a callback for invocation after an SRCU grace period
* @sp: srcu_struct in queue the callback
diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h
index 5bde94d8585..d4f559b1ec3 100644
--- a/include/trace/events/rcu.h
+++ b/include/trace/events/rcu.h
@@ -549,6 +549,7 @@ TRACE_EVENT(rcu_torture_read,
* "EarlyExit": rcu_barrier_callback() piggybacked, thus early exit.
* "Inc1": rcu_barrier_callback() piggyback check counter incremented.
* "Offline": rcu_barrier_callback() found offline CPU
+ * "OnlineNoCB": rcu_barrier_callback() found online no-CBs CPU.
* "OnlineQ": rcu_barrier_callback() found online CPU with callbacks.
* "OnlineNQ": rcu_barrier_callback() found online CPU, no callbacks.
* "IRQ": An rcu_barrier_callback() callback posted on remote CPU.