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authorMichal Hocko <mhocko@suse.cz>2011-07-08 08:48:24 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2011-09-28 21:38:23 -0700
commite5177ec77d503636d0b609671c9d408b981add17 (patch)
treed6a8e7fa1790fe04caa2d6afeabd8f09f95b5555 /Documentation/RCU/lockdep.txt
parente4cc1f22b2f4e9b0207a8cdb63e56dcf99e82d35 (diff)
rcu: Not necessary to pass rcu_read_lock_held() to rcu_dereference_protected()
Since ca5ecddf (rcu: define __rcu address space modifier for sparse) rcu_dereference_check() use rcu_read_lock_held() as a part of condition automatically. Therefore, callers of rcu_dereference_check() no longer need to pass rcu_read_lock_held() to rcu_dereference_check(). Signed-off-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'Documentation/RCU/lockdep.txt')
-rw-r--r--Documentation/RCU/lockdep.txt10
1 files changed, 4 insertions, 6 deletions
diff --git a/Documentation/RCU/lockdep.txt b/Documentation/RCU/lockdep.txt
index d7a49b2f6994..4998c633e20a 100644
--- a/Documentation/RCU/lockdep.txt
+++ b/Documentation/RCU/lockdep.txt
@@ -48,13 +48,11 @@ 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 +60,7 @@ 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.