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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@linux.vnet.ibm.com>
AuthorDate: Mon, 22 Feb 2010 17:04:48 -0800
Committer: Ingo Molnar <mingo@elte.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@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <1266887105-1528-4-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.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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