Commit 022d1b35 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

doc: Update rcu_access_pointer() advice in rcu_dereference.rst 



This commit updates the rcu_access_pointer() advice, noting that its
return value should not be assigned to a local variable, and also noting
that there is little point in using rcu_access_pointer() within an RCU
read-side critical section.

Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent ca8a439e

Documentation/RCU/rcu_dereference.rst

+10 −4
Original line number Diff line number Diff line
@@ -128,10 +128,16 @@ Follow these rules to keep your RCU code working properly: 
		This sort of comparison occurs frequently when scanning

		RCU-protected circular linked lists.



		Note that if checks for being within an RCU read-side

		critical section are not required and the pointer is never

		dereferenced, rcu_access_pointer() should be used in place

		of rcu_dereference().

		Note that if the pointer comparison is done outside

		of an RCU read-side critical section, and the pointer

		is never dereferenced, rcu_access_pointer() should be

		used in place of rcu_dereference().  In most cases,

		it is best to avoid accidental dereferences by testing

		the rcu_access_pointer() return value directly, without

		assigning it to a variable.



		Within an RCU read-side critical section, there is little

		reason to use rcu_access_pointer().



	-	The comparison is against a pointer that references memory

		that was initialized "a long time ago."  The reason