diff options
Diffstat (limited to 'Documentation/RCU/lockdep.txt')
| -rw-r--r-- | Documentation/RCU/lockdep.txt | 34 |
1 files changed, 25 insertions, 9 deletions
diff --git a/Documentation/RCU/lockdep.txt b/Documentation/RCU/lockdep.txt index d7a49b2f6994..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 @@ -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. |