RCU_READ_LOCK_HELD(9)                     Driver Basics                     RCU_READ_LOCK_HELD(9)



NAME
       rcu_read_lock_held - might we be in RCU read-side critical section?

SYNOPSIS
       int rcu_read_lock_held(void);

ARGUMENTS
       void
           no arguments

DESCRIPTION
       If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an RCU read-side critical
       section. In absence of CONFIG_DEBUG_LOCK_ALLOC, this assumes we are in an RCU read-side
       critical section unless it can prove otherwise. This is useful for debug checks in
       functions that require that they be called within an RCU read-side critical section.

       Checks debug_lockdep_rcu_enabled to prevent false positives during boot and while lockdep
       is disabled.

       Note that rcu_read_lock and the matching rcu_read_unlock must occur in the same context,
       for example, it is illegal to invoke rcu_read_unlock in process context if the matching
       rcu_read_lock was invoked from within an irq handler.

       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.

COPYRIGHT
Kernel Hackers Manual 4.8.                 January 2017                     RCU_READ_LOCK_HELD(9)