Merge git://git.kernel.org/pub/scm/linux/kernel/git/steve/linux-dm

[pandora-kernel.git] / Documentation / RCU / lockdep.txt

diff --git a/Documentation/RCU/lockdep.txt b/Documentation/RCU/lockdep.txt
index d7a49b2..a102d4b 100644 (file)
--- 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
@@ -48,13 +66,11 @@ checking of rcu_dereference() primitives:
                value of the pointer itself, for example, against NULL.
 
 The rcu_dereference_check() check expression can be any boolean
-expression, but would normally include one of the rcu_read_lock_held()
-family of functions and a lockdep expression.  However, any boolean
-expression can be used.  For a moderately ornate example, consider
-the following:
+expression, but would normally include a lockdep expression.  However,
+any boolean expression can be used.  For a moderately ornate example,
+consider the following:
 
        file = rcu_dereference_check(fdt->fd[fd],
-                                    rcu_read_lock_held() ||
                                     lockdep_is_held(&files->file_lock) ||
                                     atomic_read(&files->count) == 1);
 
@@ -62,7 +78,7 @@ This expression picks up the pointer "fdt->fd[fd]" in an RCU-safe manner,
 and, if CONFIG_PROVE_RCU is configured, verifies that this expression
 is used in:
 
-1.     An RCU read-side critical section, or
+1.     An RCU read-side critical section (implicit), or
 2.     with files->file_lock held, or
 3.     on an unshared files_struct.