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):
but retain the compiler constraints that prevent duplicating
or coalescsing. This is useful when when testing the
value of the pointer itself, for example, against NULL.
- rcu_access_index(idx):
- Return the value of the index and omit all barriers, but
- retain the compiler constraints that prevent duplicating
- or coalescsing. This is useful when when testing the
- value of the index itself, for example, against -1.
The rcu_dereference_check() check expression can be any boolean
expression, but would normally include a lockdep expression. However,