Commit 4d2f862b authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

doc: Emphasize the need for explicit RCU read-side markers 



This commit updates checklist.rst to emphasize the need for explicit
markers for RCU read-side critical sections.

Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 568035b0

Documentation/RCU/checklist.rst

+7 −2
Original line number Diff line number Diff line
@@ -66,8 +66,13 @@ over a rather long period of time, but improvements are always welcome! 
	As a rough rule of thumb, any dereference of an RCU-protected

	pointer must be covered by rcu_read_lock(), rcu_read_lock_bh(),

	rcu_read_lock_sched(), or by the appropriate update-side lock.

	Disabling of preemption can serve as rcu_read_lock_sched(), but

	is less readable and prevents lockdep from detecting locking issues.

	Explicit disabling of preemption (preempt_disable(), for example)

	can serve as rcu_read_lock_sched(), but is less readable and

	prevents lockdep from detecting locking issues.



	Please not that you *cannot* rely on code known to be built

	only in non-preemptible kernels.  Such code can and will break,

	especially in kernels built with CONFIG_PREEMPT_COUNT=y.



	Letting RCU-protected pointers "leak" out of an RCU read-side

	critical section is every bit as bad as letting them leak out