rcu: Update documentation for additional RCU lockdep functions

Add documentation for rcu_dereference_bh_check(),
rcu_dereference_sched_check(), srcu_dereference_check(), and
rcu_dereference_index_check().

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

1 files changed, 21 insertions, 3 deletions

diff --git a/Documentation/RCU/lockdep.txt b/Documentation/RCU/lockdep.txt
index 4998c633e20a..a102d4b3724b 100644
--- a/Documentation/RCU/lockdep.txt
+++ b/Documentation/RCU/lockdep.txt
@@ -32,9 +32,27 @@ checking of rcu_dereference() primitives:
         srcu_dereference(p, sp):
                 Check for SRCU read-side critical section.
         rcu_dereference_check(p, c):
-                Use explicit check expression "c".  This is useful in
-                code that is invoked by both readers and updaters.
-        rcu_dereference_raw(p)
+                Use explicit check expression "c" along with
+                rcu_read_lock_held().  This is useful in code that is
+                invoked by both RCU readers and updaters.
+        rcu_dereference_bh_check(p, c):
+                Use explicit check expression "c" along with
+                rcu_read_lock_bh_held().  This is useful in code that
+                is invoked by both RCU-bh readers and updaters.
+        rcu_dereference_sched_check(p, c):
+                Use explicit check expression "c" along with
+                rcu_read_lock_sched_held().  This is useful in code that
+                is invoked by both RCU-sched readers and updaters.
+        srcu_dereference_check(p, c):
+                Use explicit check expression "c" along with
+                srcu_read_lock_held()().  This is useful in code that
+                is invoked by both SRCU readers and updaters.
+        rcu_dereference_index_check(p, c):
+                Use explicit check expression "c", but the caller
+                must supply one of the rcu_read_lock_held() functions.
+                This is useful in code that uses RCU-protected arrays
+                that is invoked by both RCU readers and updaters.
+        rcu_dereference_raw(p):
                 Don't check.  (Use sparingly, if at all.)
         rcu_dereference_protected(p, c):
                 Use explicit check expression "c", and omit all barriers