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* [PATCH tip/core/rcu 0/21] v6 add lockdep-based diagnostics to rcu_dereference()
@ 2010-02-23  1:04 Paul E. McKenney
  2010-02-23  1:04 ` [PATCH tip/core/rcu 01/21] rcu: introduce lockdep-based checking to RCU read-side primitives Paul E. McKenney
                   ` (22 more replies)
  0 siblings, 23 replies; 85+ messages in thread
From: Paul E. McKenney @ 2010-02-23  1:04 UTC (permalink / raw)
  To: linux-kernel
  Cc: mingo, laijs, dipankar, akpm, mathieu.desnoyers, josh, dvhltc,
	niv, tglx, peterz, rostedt, Valdis.Kletnieks, dhowells

Hello!

This patch series adds lockdep-based checking to the rcu_dereference()
primitive in order to flag misuses of RCU.  The first four patches put
the RCU infrastructure in place, the next eight use this infrastructure
in the net, sched, vfs, radix-tree, idr, and security subsystems, and
patch 13 documents how to use the new lockdep-checked rcu_dereference()
primitives.  The remaining eight patches are other changes that also need
to be applied, including some relatively urgent RCU_STALL patches.

The new (and default-disabled) CONFIG_PROVE_RCU makes this safe to
include in tip/core/rcu -- unlike v2 and earlier, your system won't
complain about RCU misuse unless you ask it to.  There are still several
situations that trigger on systems I have access to (and I have email
out on a couple of them), some of the remaining will be triggered only by
hardware I don't have access to and kernel features I am unfamiliar with.
So this is ready for much wider testing.

Changes since v5 (http://lkml.org/lkml/2010/2/17/271)

o	Fix a deadlock located by Thomas Gleixner that affects
	TREE_PREEMPT_RCU in some CPU-stall detection scenarios.

o	Add Dan Carpenter's cleanup to a mod_timer() in rcutorture.

o	Add a RCU_CPU_STALL_VERBOSE to enable dumping more information
	on tasks stalling the current RCU grace period.

o	Applied Acked-by lines that people have sent (thank you all!).

Changes since v4 (http://lkml.org/lkml/2010/2/11/356)

o	Apply review comments from Peter Ziljstra.

o	Another documentation update.

o	Fixes that avoid overflowing signed integers.

o	Rebased Thomas Gleixner's raw-spinlock patch on this series.
	(Thomas's original at http://lkml.org/lkml/2010/2/17/182.)

Changes since v3 (http://lkml.org/lkml/2010/1/14/505)

o	Fix a few more issues identified by the checking.

o	Add a documentation update.

o	Accelerate RCU grace periods when the current CPU is the last
	non-dyntick-idle CPU in the system, which is important for
	some multi-core battery-powered devices.

Changes since v2 (http://lkml.org/lkml/2010/1/4/496):

o	Removed references to the check condition for the non-lockdep
	version of rcu_dereference_check(), thus preventing numerous
	build errors.

o	Create a CONFIG_PROVE_RCU (default disabled) so that developers
	who want to use lockdep only to debug locks aren't bothered 
	by RCU-specific lockdep complaints that will no doubt persist
	for a little bit while some of the more obscure uses of RCU
	are reverse-engineered.

o	Fix a few more issues identified by the checking.

o	Add documentation in Documentation/RCU/lockdep.txt.

Changes since v1 (http://lkml.org/lkml/2009/12/15/553):

o	Made SRCU have per-srcu_struct lockdep maps to prevent lockdep
	from conflating independent uses of SRCU, and updated the
	rcu_dereference() checking in rcutorture to match.

o	Fix a few issues identified by the checking.

o	Disable checking within RCU list macros, RCU radix trees, and
	IDR.

^ permalink raw reply	[flat|nested] 85+ messages in thread
* [PATCH tip/core/rcu 2/8] rcu: add lockdep-enabled variants of rcu_dereference()
@ 2010-01-05  2:04 Paul E. McKenney
  2010-01-13 10:28 ` [tip:core/rcu] rcu: Add " tip-bot for Paul E. McKenney
  0 siblings, 1 reply; 85+ messages in thread
From: Paul E. McKenney @ 2010-01-05  2:04 UTC (permalink / raw)
  To: linux-kernel
  Cc: mingo, laijs, dipankar, akpm, mathieu.desnoyers, josh, dvhltc,
	niv, tglx, peterz, rostedt, Valdis.Kletnieks, dhowells,
	Paul E. McKenney

From: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

Make rcu_dereference() check for being in an RCU read-side critical
section, and create rcu_dereference_bh(), rcu_dereference_sched(), and
srcu_dereference() to check for the other flavors of RCU.  Also create
rcu_dereference_raw() to avoid checking.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 include/linux/rcupdate.h |   45 ++++++++++++++++++++++++++++++++++-----------
 include/linux/srcu.h     |    8 ++++++++
 2 files changed, 42 insertions(+), 11 deletions(-)

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index aa6c738..a52af93 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -156,7 +156,7 @@ static inline int rcu_read_lock_sched_held(void)
 	({ \
 		if (debug_locks) \
 			WARN_ON_ONCE(!(c)); \
-		rcu_dereference(p); \
+		rcu_dereference_raw(p); \
 	})
 
 #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
@@ -183,11 +183,7 @@ static inline int rcu_read_lock_sched_held(void)
 	return preempt_count() != 0;
 }
 
-#define rcu_dereference_check(p, c) \
-	({ \
-		(void)(c); \
-		rcu_dereference(p); \
-	})
+#define rcu_dereference_check(p, c)	rcu_dereference_raw(p)
 
 #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 
@@ -323,22 +319,49 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
 
 
 /**
- * rcu_dereference - fetch an RCU-protected pointer in an
- * RCU read-side critical section.  This pointer may later
- * be safely dereferenced.
+ * rcu_dereference_raw - fetch an RCU-protected pointer
+ *
+ * The caller must be within some flavor of RCU read-side critical
+ * section, or must be otherwise preventing the pointer from changing,
+ * for example, by holding an appropriate lock.  This pointer may later
+ * be safely dereferenced.  It is the caller's responsibility to have
+ * done the right thing, as this primitive does no checking of any kind.
  *
  * Inserts memory barriers on architectures that require them
  * (currently only the Alpha), and, more importantly, documents
  * exactly which pointers are protected by RCU.
  */
-
-#define rcu_dereference(p)     ({ \
+#define rcu_dereference_raw(p)	({ \
 				typeof(p) _________p1 = ACCESS_ONCE(p); \
 				smp_read_barrier_depends(); \
 				(_________p1); \
 				})
 
 /**
+ * rcu_dereference - fetch an RCU-protected pointer, checking for RCU
+ *
+ * Makes rcu_dereference_check() do the dirty work.
+ */
+#define rcu_dereference(p) \
+	rcu_dereference_check(p, rcu_read_lock_held())
+
+/**
+ * rcu_dereference_bh - fetch an RCU-protected pointer, checking for RCU-bh
+ *
+ * Makes rcu_dereference_check() do the dirty work.
+ */
+#define rcu_dereference_bh(p) \
+		rcu_dereference_check(p, rcu_read_lock_bh_held())
+
+/**
+ * rcu_dereference_sched - fetch RCU-protected pointer, checking for RCU-sched
+ *
+ * Makes rcu_dereference_check() do the dirty work.
+ */
+#define rcu_dereference_sched(p) \
+		rcu_dereference_check(p, rcu_read_lock_sched_held())
+
+/**
  * rcu_assign_pointer - assign (publicize) a pointer to a newly
  * initialized structure that will be dereferenced by RCU read-side
  * critical sections.  Returns the value assigned.
diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index adbe167..3084f80 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -106,6 +106,14 @@ static inline int srcu_read_lock_held(struct srcu_struct *sp)
 #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 
 /**
+ * srcu_dereference - fetch SRCU-protected pointer with checking
+ *
+ * Makes rcu_dereference_check() do the dirty work.
+ */
+#define srcu_dereference(p, sp) \
+		rcu_dereference_check(p, srcu_read_lock_held(sp))
+
+/**
  * srcu_read_lock - register a new reader for an SRCU-protected structure.
  * @sp: srcu_struct in which to register the new reader.
  *
-- 
1.5.2.5


^ permalink raw reply	[flat|nested] 85+ messages in thread

end of thread, other threads:[~2010-02-26  2:12 UTC | newest]

Thread overview: 85+ messages (download: mbox.gz / follow: Atom feed)
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2010-02-23  1:04 [PATCH tip/core/rcu 0/21] v6 add lockdep-based diagnostics to rcu_dereference() Paul E. McKenney
2010-02-23  1:04 ` [PATCH tip/core/rcu 01/21] rcu: introduce lockdep-based checking to RCU read-side primitives Paul E. McKenney
2010-02-25 10:09   ` [tip:core/rcu] rcu: Introduce " tip-bot for Paul E. McKenney
2010-02-23  1:04 ` [PATCH tip/core/rcu 02/21] rcu: add lockdep-enabled variants of rcu_dereference() Paul E. McKenney
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2010-02-23  1:04 ` [PATCH tip/core/rcu 03/21] rcu: integrate rcu_dereference_check() message into lockdep Paul E. McKenney
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2010-02-23  1:04 ` [PATCH tip/core/rcu 04/21] rcu: disable lockdep checking in RCU list-traversal primitives Paul E. McKenney
2010-02-25 10:10   ` [tip:core/rcu] rcu: Disable " tip-bot for Paul E. McKenney
2010-02-23  1:04 ` [PATCH tip/core/rcu 05/21] net: add checking to rcu_dereference() primitives Paul E. McKenney
2010-02-25 10:10   ` [tip:core/rcu] net: Add " tip-bot for Paul E. McKenney
2010-02-23  1:04 ` [PATCH tip/core/rcu 06/21] sched: use lockdep-based checking on rcu_dereference() Paul E. McKenney
2010-02-25 10:11   ` [tip:core/rcu] sched: Use " tip-bot for Paul E. McKenney
2010-02-25 11:06   ` [tip:core/rcu] sched, cgroups: Fix module export tip-bot for Ingo Molnar
2010-02-23  1:04 ` [PATCH tip/core/rcu 07/21] sched: better name for for_each_domain_rd Paul E. McKenney
2010-02-25 10:11   ` [tip:core/rcu] sched: Better " tip-bot for Paul E. McKenney
2010-02-23  1:04 ` [PATCH tip/core/rcu 08/21] vfs: apply lockdep-based checking to rcu_dereference() uses Paul E. McKenney
2010-02-25 10:11   ` [tip:core/rcu] vfs: Apply " tip-bot for Paul E. McKenney
2010-02-23  1:04 ` [PATCH tip/core/rcu 09/21] vfs: abstract rcu_dereference_check for files-fdtable use Paul E. McKenney
2010-02-25 10:11   ` [tip:core/rcu] vfs: Abstract " tip-bot for Paul E. McKenney
2010-02-23  1:04 ` [PATCH tip/core/rcu 10/21] radix-tree: disable RCU lockdep checking in radix tree Paul E. McKenney
2010-02-25 10:12   ` [tip:core/rcu] radix-tree: Disable " tip-bot for Paul E. McKenney
2010-02-23  1:04 ` [PATCH tip/core/rcu 11/21] idr: apply lockdep-based diagnostics to rcu_dereference() uses Paul E. McKenney
2010-02-25 10:12   ` [tip:core/rcu] idr: Apply " tip-bot for Paul E. McKenney
2010-02-23  1:04 ` [PATCH tip/core/rcu 12/21] security: apply lockdep-based checking " Paul E. McKenney
2010-02-25 10:12   ` [tip:core/rcu] security: Apply " tip-bot for Paul E. McKenney
2010-02-23  1:04 ` [PATCH tip/core/rcu 13/21] rcu: documentation update for CONFIG_PROVE_RCU Paul E. McKenney
2010-02-25 10:12   ` [tip:core/rcu] rcu: Documentation " tip-bot for Paul E. McKenney
2010-02-23  1:04 ` [PATCH tip/core/rcu 14/21] rcu: fix citation of Mathieu's dissertation Paul E. McKenney
2010-02-25 10:13   ` [tip:core/rcu] rcu: Fix " tip-bot for Paul E. McKenney
2010-02-23  1:04 ` [PATCH tip/core/rcu 15/21] rcu: accelerate grace period if last non-dynticked CPU Paul E. McKenney
2010-02-25 10:13   ` [tip:core/rcu] rcu: Accelerate " tip-bot for Paul E. McKenney
2010-02-23  1:05 ` [PATCH tip/core/rcu 16/21] rcu: use canonical URL for Mathieu's dissertation Paul E. McKenney
2010-02-25 10:13   ` [tip:core/rcu] rcu: Use " tip-bot for Paul E. McKenney
2010-02-23  1:05 ` [PATCH tip/core/rcu 17/21] rcu: stop overflowing signed integers Paul E. McKenney
2010-02-25 10:14   ` [tip:core/rcu] rcu: Stop " tip-bot for Paul E. McKenney
2010-02-23  1:05 ` [PATCH tip/core/rcu 18/21] rcu: Convert to raw_spinlocks Paul E. McKenney
2010-02-25 10:14   ` [tip:core/rcu] " tip-bot for Paul E. McKenney
2010-02-23  1:05 ` [PATCH tip/core/rcu 19/21] rcu: fix deadlock in TREE_PREEMPT_RCU CPU stall detection Paul E. McKenney
2010-02-25 10:14   ` [tip:core/rcu] rcu: Fix " tip-bot for Paul E. McKenney
2010-02-23  1:05 ` [PATCH tip/core/rcu 20/21] rcu: fix rcutorture mod_timer argument to delay one jiffy Paul E. McKenney
2010-02-25 10:14   ` [tip:core/rcu] rcu: Fix " tip-bot for Paul E. McKenney
2010-02-23  1:05 ` [PATCH tip/core/rcu 21/21] rcu: add RCU_CPU_STALL_VERBOSE to dump detailed per-task information Paul E. McKenney
2010-02-25 10:15   ` [tip:core/rcu] rcu: Add " tip-bot for Paul E. McKenney
2010-02-23 12:59 ` [PATCH tip/core/rcu 0/21] v6 add lockdep-based diagnostics to rcu_dereference() Arnd Bergmann
2010-02-23 13:15   ` Mathieu Desnoyers
2010-02-23 14:35     ` Paul E. McKenney
2010-02-23 15:54     ` Arnd Bergmann
2010-02-23 16:16       ` Paul E. McKenney
2010-02-23 17:15         ` Arnd Bergmann
2010-02-23 18:01           ` Paul E. McKenney
2010-02-24 20:03             ` [PATCH 00/10] __rcu annotations, first draft Arnd Bergmann
2010-02-24 22:18               ` Paul E. McKenney
2010-02-25  8:37               ` Ingo Molnar
2010-02-24 20:03             ` [PATCH 01/10] rcu: define __rcu address space modifier for sparse Arnd Bergmann
2010-02-24 20:12               ` Mathieu Desnoyers
2010-02-24 20:22                 ` Arnd Bergmann
2010-02-24 20:03             ` [PATCH 02/10] rcu: annotated list rcu code Arnd Bergmann
2010-02-24 20:15               ` Mathieu Desnoyers
2010-02-24 20:32                 ` Arnd Bergmann
2010-02-24 20:03             ` [PATCH 03/10] cgroups: __rcu annotations Arnd Bergmann
2010-02-24 20:04             ` [PATCH 04/10] credentials: rcu annotation Arnd Bergmann
2010-02-24 20:04             ` [PATCH 05/10] perf_event: __rcu annotations Arnd Bergmann
2010-02-24 20:04             ` [PATCH 06/10] audit: " Arnd Bergmann
2010-02-24 20:04             ` [PATCH 07/10] module: " Arnd Bergmann
2010-02-24 20:13               ` Alexey Dobriyan
2010-02-24 20:26                 ` Arnd Bergmann
2010-02-24 22:17                   ` Paul E. McKenney
2010-02-24 23:07                     ` Arnd Bergmann
2010-02-24 23:59                       ` Paul E. McKenney
2010-02-25 17:06                         ` Paul E. McKenney
2010-02-25 18:10                           ` Arnd Bergmann
2010-02-25 20:05                             ` Paul E. McKenney
2010-02-26  2:12                               ` Paul E. McKenney
2010-02-24 20:04             ` [PATCH 08/10] pid: " Arnd Bergmann
2010-02-24 20:04             ` [PATCH 09/10] notifiers: " Arnd Bergmann
2010-02-24 20:04             ` [PATCH 10/10] scheduler: " Arnd Bergmann
2010-02-23 13:28   ` [PATCH tip/core/rcu 0/21] v6 add lockdep-based diagnostics to rcu_dereference() Paul E. McKenney
2010-02-25 10:00 ` Ingo Molnar
2010-02-25 10:01   ` Ingo Molnar
2010-02-25 12:04     ` Ingo Molnar
2010-02-25 18:18       ` Paul E. McKenney
2010-02-25 21:36         ` Paul E. McKenney
2010-02-25 21:22       ` Ingo Molnar
  -- strict thread matches above, loose matches on Subject: below --
2010-01-05  2:04 [PATCH tip/core/rcu 2/8] rcu: add lockdep-enabled variants of rcu_dereference() Paul E. McKenney
2010-01-13 10:28 ` [tip:core/rcu] rcu: Add " tip-bot for Paul E. McKenney

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