Add expedited functions. Review documentation and update obsolete verbiage. Also fix the advice for the RCU CPU-stall kernel configuration parameter, and document RCU CPU-stall warnings.

---
 Documentation/RCU/00-INDEX                   |    8 +-
 Documentation/RCU/RTFP.txt                   |   58 +++++++-
 Documentation/RCU/checklist.txt              |  200 +++++++++++++++-----------
 Documentation/RCU/rcu.txt                    |   48 +------
 Documentation/RCU/stallwarn.txt              |   58 ++++++++
 Documentation/RCU/torture.txt                |   12 ++
 Documentation/RCU/whatisRCU.txt              |    3 +-
 Documentation/filesystems/dentry-locking.txt |    3 +-
 lib/Kconfig.debug                            |    4 +-
 9 files changed, 258 insertions(+), 136 deletions(-)
 create mode 100644 Documentation/RCU/stallwarn.txt

Documentation/RCU/00-INDEX +6 -2

index 9bb62f7..0a27ea9 100644
@@ -8,14 +8,18 @@ listRCU.txt
 	- Using RCU to Protect Read-Mostly Linked Lists
 NMI-RCU.txt
 	- Using RCU to Protect Dynamic NMI Handlers
+rcubarrier.txt
+	- RCU and Unloadable Modules
+rculist_nulls.txt
+	- RCU list primitives for use with SLAB_DESTROY_BY_RCU
 rcuref.txt
 	- Reference-count design for elements of lists/arrays protected by RCU
 rcu.txt
 	- RCU Concepts
-rcubarrier.txt
-	- Unloading modules that use RCU callbacks
 RTFP.txt
 	- List of RCU papers (bibliography) going back to 1980.
+stallwarn.txt
+	- RCU CPU stall warnings (CONFIG_RCU_CPU_STALL_DETECTOR)
 torture.txt
 	- RCU Torture Test Operation (CONFIG_RCU_TORTURE_TEST)
 trace.txt

Documentation/RCU/RTFP.txt +54 -4

79 lines not on this page · raw message

Documentation/RCU/checklist.txt +119 ~~-81~~

297 lines not on this page · raw message

Documentation/RCU/rcu.txt +3 ~~-45~~

57 lines not on this page · raw message

Documentation/RCU/stallwarn.txt new file +58 -0

58 lines not on this page · raw message

Documentation/RCU/torture.txt +12 -0

index 9dba3bb..0e50bc2 100644
@@ -30,6 +30,18 @@ MODULE PARAMETERS
 
 This module has the following parameters:
 
+fqs_duration	Duration (in microseconds) of artificially induced bursts
+		of force_quiescent_state() invocations.  In RCU
+		implementations having force_quiescent_state(), these
+		bursts help force races between forcing a given grace
+		period and that grace period ending on its own.
+
+fqs_holdoff	Holdoff time (in microseconds) between consecutive calls
+		to force_quiescent_state() within a burst.
+
+fqs_stutter	Wait time (in seconds) between consecutive bursts
+		of calls to force_quiescent_state().
+
 irqreaders	Says to invoke RCU readers from irq level.  This is currently
 		done via timers.  Defaults to "1" for variants of RCU that
 		permit this.  (Or, more accurately, variants of RCU that do

Documentation/RCU/whatisRCU.txt +2 -1

index d542ca2..469a58b 100644
@@ -327,7 +327,8 @@ a.	synchronize_rcu()	rcu_read_lock() / rcu_read_unlock()
 
 b.	call_rcu_bh()		rcu_read_lock_bh() / rcu_read_unlock_bh()
 
-c.	synchronize_sched()	preempt_disable() / preempt_enable()
+c.	synchronize_sched()	rcu_read_lock_sched() / rcu_read_unlock_sched()
+				preempt_disable() / preempt_enable()
 				local_irq_save() / local_irq_restore()
 				hardirq enter / hardirq exit
 				NMI enter / NMI exit

Documentation/filesystems/dentry-locking.txt +2 -1

index 4c0c575..79334ed 100644
@@ -62,7 +62,8 @@ changes are :
 2. Insertion of a dentry into the hash table is done using
    hlist_add_head_rcu() which take care of ordering the writes - the
    writes to the dentry must be visible before the dentry is
-   inserted. This works in conjunction with hlist_for_each_rcu() while
+   inserted. This works in conjunction with hlist_for_each_rcu(),
+   which has since been replaced by hlist_for_each_entry_rcu(), while
    walking the hash chain. The only requirement is that all
    initialization to the dentry must be done before
    hlist_add_head_rcu() since we don't have dcache_lock protection

lib/Kconfig.debug +2 -2

index 25c3ed5..6bf97d1 100644
@@ -765,9 +765,9 @@ config RCU_CPU_STALL_DETECTOR
 	  CPUs are delaying the current grace period, but only when
 	  the grace period extends for excessive time periods.
 
-	  Say Y if you want RCU to perform such checks.
+	  Say N if you want to disable such checks.
 
-	  Say N if you are unsure.
+	  Say Y if you are unsure.
 
 config KPROBES_SANITY_TEST
 	bool "Kprobes sanity tests"

Signature · 1 line

1.5.2.5

tip-bot for Paul E. McKenney

author

2010-01-16 09:45 UTC #2 lore raw

[tip:core/rcu] rcu: 1Q2010 update for RCU documentation

Commit-ID:  4c54005ca438a8b46dd542b497d4f0dc2ca375e8
Gitweb:     http://git.kernel.org/tip/4c54005ca438a8b46dd542b497d4f0dc2ca375e8
Author:     Paul E. McKenney <[email protected]>
AuthorDate: Thu, 14 Jan 2010 16:10:57 -0800
Committer:  Ingo Molnar <[email protected]>
CommitDate: Sat, 16 Jan 2010 10:25:22 +0100

rcu: 1Q2010 update for RCU documentation

Add expedited functions. Review documentation and update obsolete verbiage. Also fix the advice for the RCU CPU-stall kernel configuration parameter, and document RCU CPU-stall warnings.

Signed-off-by Paul E. McKenney <[email protected]>

Cc [email protected]

LKML-Reference: <12635142581866-git-send-email->

Signed-off-by Ingo Molnar <[email protected]>

---
 Documentation/RCU/00-INDEX                   |    8 +-
 Documentation/RCU/RTFP.txt                   |   58 +++++++-
 Documentation/RCU/checklist.txt              |  200 +++++++++++++++-----------
 Documentation/RCU/rcu.txt                    |   48 +------
 Documentation/RCU/stallwarn.txt              |   58 ++++++++
 Documentation/RCU/torture.txt                |   12 ++
 Documentation/RCU/whatisRCU.txt              |    3 +-
 Documentation/filesystems/dentry-locking.txt |    3 +-
 lib/Kconfig.debug                            |    4 +-
 9 files changed, 258 insertions(+), 136 deletions(-)

Documentation/RCU/00-INDEX +6 -2

index 9bb62f7..0a27ea9 100644
@@ -8,14 +8,18 @@ listRCU.txt
 	- Using RCU to Protect Read-Mostly Linked Lists
 NMI-RCU.txt
 	- Using RCU to Protect Dynamic NMI Handlers
+rcubarrier.txt
+	- RCU and Unloadable Modules
+rculist_nulls.txt
+	- RCU list primitives for use with SLAB_DESTROY_BY_RCU
 rcuref.txt
 	- Reference-count design for elements of lists/arrays protected by RCU
 rcu.txt
 	- RCU Concepts
-rcubarrier.txt
-	- Unloading modules that use RCU callbacks
 RTFP.txt
 	- List of RCU papers (bibliography) going back to 1980.
+stallwarn.txt
+	- RCU CPU stall warnings (CONFIG_RCU_CPU_STALL_DETECTOR)
 torture.txt
 	- RCU Torture Test Operation (CONFIG_RCU_TORTURE_TEST)
 trace.txt

Documentation/RCU/RTFP.txt +54 -4

79 lines not on this page · raw message

Documentation/RCU/checklist.txt +119 ~~-81~~

297 lines not on this page · raw message

Documentation/RCU/rcu.txt +3 ~~-45~~

57 lines not on this page · raw message

Documentation/RCU/stallwarn.txt new file +58 -0

58 lines not on this page · raw message

Documentation/RCU/torture.txt +12 -0

index 9dba3bb..0e50bc2 100644
@@ -30,6 +30,18 @@ MODULE PARAMETERS
 
 This module has the following parameters:
 
+fqs_duration	Duration (in microseconds) of artificially induced bursts
+		of force_quiescent_state() invocations.  In RCU
+		implementations having force_quiescent_state(), these
+		bursts help force races between forcing a given grace
+		period and that grace period ending on its own.
+
+fqs_holdoff	Holdoff time (in microseconds) between consecutive calls
+		to force_quiescent_state() within a burst.
+
+fqs_stutter	Wait time (in seconds) between consecutive bursts
+		of calls to force_quiescent_state().
+
 irqreaders	Says to invoke RCU readers from irq level.  This is currently
 		done via timers.  Defaults to "1" for variants of RCU that
 		permit this.  (Or, more accurately, variants of RCU that do

Documentation/RCU/whatisRCU.txt +2 -1

index d542ca2..469a58b 100644
@@ -327,7 +327,8 @@ a.	synchronize_rcu()	rcu_read_lock() / rcu_read_unlock()
 
 b.	call_rcu_bh()		rcu_read_lock_bh() / rcu_read_unlock_bh()
 
-c.	synchronize_sched()	preempt_disable() / preempt_enable()
+c.	synchronize_sched()	rcu_read_lock_sched() / rcu_read_unlock_sched()
+				preempt_disable() / preempt_enable()
 				local_irq_save() / local_irq_restore()
 				hardirq enter / hardirq exit
 				NMI enter / NMI exit

Documentation/filesystems/dentry-locking.txt +2 -1

index 4c0c575..79334ed 100644
@@ -62,7 +62,8 @@ changes are :
 2. Insertion of a dentry into the hash table is done using
    hlist_add_head_rcu() which take care of ordering the writes - the
    writes to the dentry must be visible before the dentry is
-   inserted. This works in conjunction with hlist_for_each_rcu() while
+   inserted. This works in conjunction with hlist_for_each_rcu(),
+   which has since been replaced by hlist_for_each_entry_rcu(), while
    walking the hash chain. The only requirement is that all
    initialization to the dentry must be done before
    hlist_add_head_rcu() since we don't have dcache_lock protection

lib/Kconfig.debug +2 -2

index 25c3ed5..6bf97d1 100644
@@ -765,9 +765,9 @@ config RCU_CPU_STALL_DETECTOR
 	  CPUs are delaying the current grace period, but only when
 	  the grace period extends for excessive time periods.
 
-	  Say Y if you want RCU to perform such checks.
+	  Say N if you want to disable such checks.
 
-	  Say N if you are unsure.
+	  Say Y if you are unsure.
 
 config KPROBES_SANITY_TEST
 	bool "Kprobes sanity tests"

Paul E. McKenney

author

2010-01-15 00:11 UTC #3 lore raw

PATCH 2/2 rcu: fix sparse warnings

In reply to Paul E. McKenney

From: Paul E. McKenney <[email protected]>

Rename local variable "i" in rcu_init() to avoid conflict with RCU_INIT_FLAVOR(), restrict the scope of RCU_TREE_NONCORE, and make __synchronize_srcu() static.

Signed-off-by Paul E. McKenney <[email protected]>

---
 kernel/rcutree.c |    6 +++---
 kernel/rcutree.h |    6 ++----
 kernel/srcu.c    |    2 +-
 3 files changed, 6 insertions(+), 8 deletions(-)

kernel/rcutree.c +3 -3

index 3b13d64..099a255 100644
@@ -1888,7 +1888,7 @@ do { \
 
 void __init rcu_init(void)
 {
-	int i;
+	int cpu;
 
 	rcu_bootup_announce();
 #ifdef CONFIG_RCU_CPU_STALL_DETECTOR

@@ -1908,8 +1908,8 @@ void __init rcu_init(void)
 	 * or the scheduler are operational.
 	 */
 	cpu_notifier(rcu_cpu_notify, 0);
-	for_each_online_cpu(i)
-		rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)i);
+	for_each_online_cpu(cpu)
+		rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)cpu);
 }
 
 #include "rcutree_plugin.h"

kernel/rcutree.h +2 -4

index bd5d78a..d9d032a 100644
@@ -323,8 +323,6 @@ struct rcu_state {
 #define RCU_OFL_TASKS_EXP_GP	0x2		/* Tasks blocking expedited */
 						/*  GP were moved to root. */
 
-#ifdef RCU_TREE_NONCORE
-
 /*
  * RCU implementation internal declarations:
  */

@@ -339,7 +337,7 @@ extern struct rcu_state rcu_preempt_state;
 DECLARE_PER_CPU(struct rcu_data, rcu_preempt_data);
 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
 
-#else /* #ifdef RCU_TREE_NONCORE */
+#ifndef RCU_TREE_NONCORE
 
 /* Forward declarations for rcutree_plugin.h */
 static void rcu_bootup_announce(void);

@@ -372,4 +370,4 @@ static void __cpuinit rcu_preempt_init_percpu_data(int cpu);
 static void rcu_preempt_send_cbs_to_orphanage(void);
 static void __init __rcu_init_preempt(void);
 
-#endif /* #else #ifdef RCU_TREE_NONCORE */
+#endif /* #ifndef RCU_TREE_NONCORE */

kernel/srcu.c +1 -1

index 818d7d9..31b275b 100644
@@ -144,7 +144,7 @@ EXPORT_SYMBOL_GPL(srcu_read_unlock);
 /*
  * Helper function for synchronize_srcu() and synchronize_srcu_expedited().
  */
-void __synchronize_srcu(struct srcu_struct *sp, void (*sync_func)(void))
+static void __synchronize_srcu(struct srcu_struct *sp, void (*sync_func)(void))
 {
 	int idx;

Signature · 1 line

1.5.2.5

tip-bot for Paul E. McKenney

author

2010-01-16 09:45 UTC #4 lore raw

[tip:core/rcu] rcu: Fix sparse warnings

Commit-ID:  017c426138122c8e9b9f5057fbd0567c37b35247
Gitweb:     http://git.kernel.org/tip/017c426138122c8e9b9f5057fbd0567c37b35247
Author:     Paul E. McKenney <[email protected]>
AuthorDate: Thu, 14 Jan 2010 16:10:58 -0800
Committer:  Ingo Molnar <[email protected]>
CommitDate: Sat, 16 Jan 2010 10:25:22 +0100

rcu: Fix sparse warnings

Rename local variable "i" in rcu_init() to avoid conflict with RCU_INIT_FLAVOR(), restrict the scope of RCU_TREE_NONCORE, and make __synchronize_srcu() static.

Signed-off-by Paul E. McKenney <[email protected]>

Cc [email protected]

LKML-Reference: <12635142581560-git-send-email->

Signed-off-by Ingo Molnar <[email protected]>

---
 kernel/rcutree.c |    6 +++---
 kernel/rcutree.h |    6 ++----
 kernel/srcu.c    |    2 +-
 3 files changed, 6 insertions(+), 8 deletions(-)

kernel/rcutree.c +3 -3

index 3b13d64..099a255 100644
@@ -1888,7 +1888,7 @@ do { \
 
 void __init rcu_init(void)
 {
-	int i;
+	int cpu;
 
 	rcu_bootup_announce();
 #ifdef CONFIG_RCU_CPU_STALL_DETECTOR

@@ -1908,8 +1908,8 @@ void __init rcu_init(void)
 	 * or the scheduler are operational.
 	 */
 	cpu_notifier(rcu_cpu_notify, 0);
-	for_each_online_cpu(i)
-		rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)i);
+	for_each_online_cpu(cpu)
+		rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)cpu);
 }
 
 #include "rcutree_plugin.h"

kernel/rcutree.h +2 -4

index bd5d78a..d9d032a 100644
@@ -323,8 +323,6 @@ struct rcu_state {
 #define RCU_OFL_TASKS_EXP_GP	0x2		/* Tasks blocking expedited */
 						/*  GP were moved to root. */
 
-#ifdef RCU_TREE_NONCORE
-
 /*
  * RCU implementation internal declarations:
  */

@@ -339,7 +337,7 @@ extern struct rcu_state rcu_preempt_state;
 DECLARE_PER_CPU(struct rcu_data, rcu_preempt_data);
 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
 
-#else /* #ifdef RCU_TREE_NONCORE */
+#ifndef RCU_TREE_NONCORE
 
 /* Forward declarations for rcutree_plugin.h */
 static void rcu_bootup_announce(void);

@@ -372,4 +370,4 @@ static void __cpuinit rcu_preempt_init_percpu_data(int cpu);
 static void rcu_preempt_send_cbs_to_orphanage(void);
 static void __init __rcu_init_preempt(void);
 
-#endif /* #else #ifdef RCU_TREE_NONCORE */
+#endif /* #ifndef RCU_TREE_NONCORE */

kernel/srcu.c +1 -1

index 818d7d9..31b275b 100644
@@ -144,7 +144,7 @@ EXPORT_SYMBOL_GPL(srcu_read_unlock);
 /*
  * Helper function for synchronize_srcu() and synchronize_srcu_expedited().
  */
-void __synchronize_srcu(struct srcu_struct *sp, void (*sync_func)(void))
+static void __synchronize_srcu(struct srcu_struct *sp, void (*sync_func)(void))
 {
 	int idx;