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Groups > linux.kernel > #1169907

[RFC][PATCH 03/13] rcusync: Add the CONFIG_PROVE_RCU checks

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It would be nice to validate that the caller of rcu_sync_is_idle()
holds the corresponding type of RCU read-side lock. Add the new
rcu_sync_ops->held() method and change rcu_sync_is_idle() to
WARN() if it returns false.

This obviously penalizes the readers (fast-path), but only if
CONFIG_PROVE_RCU.

Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Suggested-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 include/linux/rcusync.h |    6 ++++++
 kernel/rcu/sync.c       |   21 +++++++++++++++++++++
 2 files changed, 27 insertions(+)

--- a/include/linux/rcusync.h
+++ b/include/linux/rcusync.h
@@ -17,9 +17,15 @@ struct rcu_sync_struct {
 	enum rcu_sync_type	gp_type;
 };
 
+extern bool __rcu_sync_is_idle(struct rcu_sync_struct *);
+
 static inline bool rcu_sync_is_idle(struct rcu_sync_struct *rss)
 {
+#ifdef CONFIG_PROVE_RCU
+	return __rcu_sync_is_idle(rss);
+#else
 	return !rss->gp_state; /* GP_IDLE */
+#endif
 }
 
 extern void rcu_sync_init(struct rcu_sync_struct *, enum rcu_sync_type);
--- a/kernel/rcu/sync.c
+++ b/kernel/rcu/sync.c
@@ -1,21 +1,33 @@
 #include <linux/rcusync.h>
 #include <linux/sched.h>
 
+#ifdef CONFIG_PROVE_RCU
+#define __INIT_HELD(func)	.held = func,
+#else
+#define __INIT_HELD(func)
+#endif
+
 static const struct {
 	void (*sync)(void);
 	void (*call)(struct rcu_head *, void (*)(struct rcu_head *));
+#ifdef CONFIG_PROVE_RCU
+	int  (*held)(void);
+#endif
 } gp_ops[] = {
 	[RCU_SYNC] = {
 		.sync = synchronize_rcu,
 		.call = call_rcu,
+		__INIT_HELD(rcu_read_lock_held)
 	},
 	[RCU_SCHED_SYNC] = {
 		.sync = synchronize_sched,
 		.call = call_rcu_sched,
+		__INIT_HELD(rcu_read_lock_sched_held)
 	},
 	[RCU_BH_SYNC] = {
 		.sync = synchronize_rcu_bh,
 		.call = call_rcu_bh,
+		__INIT_HELD(rcu_read_lock_bh_held)
 	},
 };
 
@@ -24,6 +36,15 @@ enum { CB_IDLE = 0, CB_PENDING, CB_REPLA
 
 #define	rss_lock	gp_wait.lock
 
+#ifdef CONFIG_PROVE_RCU
+bool __rcu_sync_is_idle(struct rcu_sync_struct *rss)
+{
+	WARN_ON(!gp_ops[rss->gp_type].held());
+	return rss->gp_state == GP_IDLE;
+}
+EXPORT_SYMBOL_GPL(__rcu_sync_is_idle);
+#endif
+
 void rcu_sync_init(struct rcu_sync_struct *rss, enum rcu_sync_type type)
 {
 	memset(rss, 0, sizeof(*rss));


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[RFC][PATCH 00/13] percpu rwsem -v2 Peter Zijlstra <peterz@infradead.org> - 2015-06-22 14:30 +0200
  [RFC][PATCH 01/13] rcu: Create rcu_sync infrastructure Peter Zijlstra <peterz@infradead.org> - 2015-06-22 14:30 +0200
  [RFC][PATCH 05/13] percpu-rwsem: Optimize readers and reduce global impact Peter Zijlstra <peterz@infradead.org> - 2015-06-22 14:30 +0200
    Re: [RFC][PATCH 05/13] percpu-rwsem: Optimize readers and reduce  global impact Oleg Nesterov <oleg@redhat.com> - 2015-06-23 01:10 +0200
    Re: [RFC][PATCH 05/13] percpu-rwsem: Optimize readers and reduce  global impact Tejun Heo <tj@kernel.org> - 2015-06-29 17:20 +0200
      Re: [RFC][PATCH 05/13] percpu-rwsem: Optimize readers and reduce  global impact Peter Zijlstra <peterz@infradead.org> - 2015-06-29 17:20 +0200
  [RFC][PATCH 11/13] fs/locks: Replace lg_local with a per-cpu spinlock Peter Zijlstra <peterz@infradead.org> - 2015-06-22 14:30 +0200
    Re: [RFC][PATCH 11/13] fs/locks: Replace lg_local with a per-cpu  spinlock Oleg Nesterov <oleg@redhat.com> - 2015-06-23 02:30 +0200
  [RFC][PATCH 10/13] fs/locks: Replace lg_global with a percpu-rwsem Peter Zijlstra <peterz@infradead.org> - 2015-06-22 14:30 +0200
  [RFC][PATCH 12/13] stop_machine: Remove lglock Peter Zijlstra <peterz@infradead.org> - 2015-06-22 14:30 +0200
    Re: [RFC][PATCH 12/13] stop_machine: Remove lglock Oleg Nesterov <oleg@redhat.com> - 2015-06-23 00:30 +0200
      Re: [RFC][PATCH 12/13] stop_machine: Remove lglock "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-06-24 04:30 +0200
        Re: [RFC][PATCH 12/13] stop_machine: Remove lglock Peter Zijlstra <peterz@infradead.org> - 2015-06-24 10:40 +0200
      Re: [RFC][PATCH 12/13] stop_machine: Remove lglock Peter Zijlstra <peterz@infradead.org> - 2015-06-24 09:40 +0200
        Re: [RFC][PATCH 12/13] stop_machine: Remove lglock Ingo Molnar <mingo@kernel.org> - 2015-06-24 10:50 +0200
  [RFC][PATCH 13/13] locking: Remove lglock Peter Zijlstra <peterz@infradead.org> - 2015-06-22 14:30 +0200
  [RFC][PATCH 03/13] rcusync: Add the CONFIG_PROVE_RCU checks Peter Zijlstra <peterz@infradead.org> - 2015-06-22 14:30 +0200
  [RFC][PATCH 07/13] sched: Reorder task_struct Peter Zijlstra <peterz@infradead.org> - 2015-06-22 14:30 +0200
  Re: [RFC][PATCH 00/13] percpu rwsem -v2 Peter Zijlstra <peterz@infradead.org> - 2015-06-22 14:40 +0200
  Re: [RFC][PATCH 00/13] percpu rwsem -v2 Linus Torvalds <torvalds@linux-foundation.org> - 2015-06-22 22:10 +0200
  Re: [RFC][PATCH 00/13] percpu rwsem -v2 Ingo Molnar <mingo@kernel.org> - 2015-06-24 10:50 +0200
    Re: [RFC][PATCH 00/13] percpu rwsem -v2 Peter Zijlstra <peterz@infradead.org> - 2015-06-24 11:10 +0200
    Re: [RFC][PATCH 00/13] percpu rwsem -v2 Daniel Wagner <daniel.wagner@bmw-carit.de> - 2015-06-24 11:20 +0200
      Re: [RFC][PATCH 00/13] percpu rwsem -v2 Linus Torvalds <torvalds@linux-foundation.org> - 2015-07-02 00:00 +0200
        Re: [RFC][PATCH 00/13] percpu rwsem -v2 Peter Zijlstra <peterz@infradead.org> - 2015-07-02 11:50 +0200

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