linux-kernel - [tip:core/rcu] rcu: Disable lockdep checking in RCU list-traversal primitives

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Message-ID: <tip-3120438ad68601f341e61e7cb1323b0e1a6ca367@git.kernel.org>
Date:	Thu, 25 Feb 2010 10:10:04 GMT
From:	"tip-bot for Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, paulmck@...ux.vnet.ibm.com,
	hpa@...or.com, mingo@...hat.com, tglx@...utronix.de, mingo@...e.hu
Subject: [tip:core/rcu] rcu: Disable lockdep checking in RCU list-traversal primitives

Commit-ID:  3120438ad68601f341e61e7cb1323b0e1a6ca367
Gitweb:     http://git.kernel.org/tip/3120438ad68601f341e61e7cb1323b0e1a6ca367
Author:     Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
AuthorDate: Mon, 22 Feb 2010 17:04:48 -0800
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Thu, 25 Feb 2010 09:41:02 +0100

rcu: Disable lockdep checking in RCU list-traversal primitives

The theory is that use of bare rcu_dereference() is more prone
to error than use of the RCU list-traversal primitives.
Therefore, disable lockdep RCU read-side critical-section
checking in these primitives for the time being.  Once all of
the rcu_dereference() uses have been dealt with, it may be time
to re-enable lockdep checking for the RCU list-traversal
primitives.

Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: laijs@...fujitsu.com
Cc: dipankar@...ibm.com
Cc: mathieu.desnoyers@...ymtl.ca
Cc: josh@...htriplett.org
Cc: dvhltc@...ibm.com
Cc: niv@...ibm.com
Cc: peterz@...radead.org
Cc: rostedt@...dmis.org
Cc: Valdis.Kletnieks@...edu
Cc: dhowells@...hat.com
LKML-Reference: <1266887105-1528-4-git-send-email-paulmck@...ux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 include/linux/rculist.h       |   14 +++++++-------
 include/linux/rculist_nulls.h |    4 ++--
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index 1bf0f70..779d707 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -208,7 +208,7 @@ static inline void list_splice_init_rcu(struct list_head *list,
  * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().
  */
 #define list_entry_rcu(ptr, type, member) \
-	container_of(rcu_dereference(ptr), type, member)
+	container_of(rcu_dereference_raw(ptr), type, member)
 
 /**
  * list_first_entry_rcu - get the first element from a list
@@ -225,9 +225,9 @@ static inline void list_splice_init_rcu(struct list_head *list,
 	list_entry_rcu((ptr)->next, type, member)
 
 #define __list_for_each_rcu(pos, head) \
-	for (pos = rcu_dereference((head)->next); \
+	for (pos = rcu_dereference_raw((head)->next); \
 		pos != (head); \
-		pos = rcu_dereference(pos->next))
+		pos = rcu_dereference_raw(pos->next))
 
 /**
  * list_for_each_entry_rcu	-	iterate over rcu list of given type
@@ -257,9 +257,9 @@ static inline void list_splice_init_rcu(struct list_head *list,
  * as long as the traversal is guarded by rcu_read_lock().
  */
 #define list_for_each_continue_rcu(pos, head) \
-	for ((pos) = rcu_dereference((pos)->next); \
+	for ((pos) = rcu_dereference_raw((pos)->next); \
 		prefetch((pos)->next), (pos) != (head); \
-		(pos) = rcu_dereference((pos)->next))
+		(pos) = rcu_dereference_raw((pos)->next))
 
 /**
  * list_for_each_entry_continue_rcu - continue iteration over list of given type
@@ -418,10 +418,10 @@ static inline void hlist_add_after_rcu(struct hlist_node *prev,
  * as long as the traversal is guarded by rcu_read_lock().
  */
 #define hlist_for_each_entry_rcu(tpos, pos, head, member)		 \
-	for (pos = rcu_dereference((head)->first);			 \
+	for (pos = rcu_dereference_raw((head)->first);			 \
 		pos && ({ prefetch(pos->next); 1; }) &&			 \
 		({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; }); \
-		pos = rcu_dereference(pos->next))
+		pos = rcu_dereference_raw(pos->next))
 
 #endif	/* __KERNEL__ */
 #endif
diff --git a/include/linux/rculist_nulls.h b/include/linux/rculist_nulls.h
index 589a409..b70ffe5 100644
--- a/include/linux/rculist_nulls.h
+++ b/include/linux/rculist_nulls.h
@@ -101,10 +101,10 @@ static inline void hlist_nulls_add_head_rcu(struct hlist_nulls_node *n,
  *
  */
 #define hlist_nulls_for_each_entry_rcu(tpos, pos, head, member) \
-	for (pos = rcu_dereference((head)->first);			 \
+	for (pos = rcu_dereference_raw((head)->first);			 \
 		(!is_a_nulls(pos)) &&			\
 		({ tpos = hlist_nulls_entry(pos, typeof(*tpos), member); 1; }); \
-		pos = rcu_dereference(pos->next))
+		pos = rcu_dereference_raw(pos->next))
 
 #endif
 #endif
--
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