Man page 9 : rcu_read_lock_bh_held

rcu_read_lock_bh_held - might we be in RCU-bh read-side critical section?

int rcu_read_lock_bh_held( void );

void
    no arguments

Check for bottom half being disabled, which covers both the CONFIG_PROVE_RCU and not cases. Note that if someone uses rcu_read_lock_bh, but then later enables BH, lockdep (if enabled) will show the situation. This is useful for debug checks in functions that require that they be called within an RCU read-side critical section.

Check debug_lockdep_rcu_enabled to prevent false positives during boot.

Note that rcu_read_lock is disallowed if the CPU is either idle or offline from an RCU perspective, so check for those as well.