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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2010-04-28 14:39:09 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2010-08-19 17:17:59 -0700
commitca5ecddfa8fcbd948c95530e7e817cee9fb43a3d (patch)
tree0ad1c320c2e6612a9a230a58d8588850701c048c /kernel/rcupdate.c
parentd34a16661ed0fed433c9469d7cfa3ca4d30ca42e (diff)
rcu: define __rcu address space modifier for sparse
This commit provides definitions for the __rcu annotation defined earlier. This annotation permits sparse to check for correct use of RCU-protected pointers. If a pointer that is annotated with __rcu is accessed directly (as opposed to via rcu_dereference(), rcu_assign_pointer(), or one of their variants), sparse can be made to complain. To enable such complaints, use the new default-disabled CONFIG_SPARSE_RCU_POINTER kernel configuration option. Please note that these sparse complaints are intended to be a debugging aid, -not- a code-style-enforcement mechanism. There are special rcu_dereference_protected() and rcu_access_pointer() accessors for use when RCU read-side protection is not required, for example, when no other CPU has access to the data structure in question or while the current CPU hold the update-side lock. This patch also updates a number of docbook comments that were showing their age. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Christopher Li <sparse@chrisli.org> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Diffstat (limited to 'kernel/rcupdate.c')
-rw-r--r--kernel/rcupdate.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index 4d169835fb3..6c79e851521 100644
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -73,12 +73,14 @@ int debug_lockdep_rcu_enabled(void)
EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled);
/**
- * rcu_read_lock_bh_held - might we be in RCU-bh read-side critical section?
+ * rcu_read_lock_bh_held() - might we be in RCU-bh read-side critical section?
*
* Check for bottom half being disabled, which covers both the
* CONFIG_PROVE_RCU and not cases. Note that if someone uses
* rcu_read_lock_bh(), but then later enables BH, lockdep (if enabled)
- * will show the situation.
+ * will show the situation. This is useful for debug checks in functions
+ * that require that they be called within an RCU read-side critical
+ * section.
*
* Check debug_lockdep_rcu_enabled() to prevent false positives during boot.
*/