locking/barriers: Kill lockless_dereference()

lockless_dereference() is a nice idea, but it gained little traction in
kernel code since its introduction three years ago. This is partly
because it's a pain to type, but also because using READ_ONCE() instead
has worked correctly on all architectures apart from Alpha, which is a
fully supported but somewhat niche architecture these days.

Now that READ_ONCE() has been upgraded to contain an implicit
smp_read_barrier_depends() and the few callers of lockless_dereference()
have been converted, we can remove lockless_dereference() altogether.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-5-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 0 insertions, 12 deletions

diff --git a/Documentation/translations/ko_KR/memory-barriers.txt b/Documentation/translations/ko_KR/memory-barriers.txt
index a7a813258013..ec3b46e27b7a 100644
--- a/Documentation/translations/ko_KR/memory-barriers.txt
+++ b/Documentation/translations/ko_KR/memory-barriers.txt
@@ -1858,18 +1858,6 @@ Mandatory 배리어들은 SMP 시스템에서도 UP 시스템에서도 SMP 효�
      참고하세요.
 
 
- (*) lockless_dereference();
-
-     이 함수는 smp_read_barrier_depends() 데이터 의존성 배리어를 사용하는
-     포인터 읽어오기 래퍼(wrapper) 함수로 생각될 수 있습니다.
-
-     객체의 라이프타임이 RCU 외의 메커니즘으로 관리된다는 점을 제외하면
-     rcu_dereference() 와도 유사한데, 예를 들면 객체가 시스템이 꺼질 때에만
-     제거되는 경우 등입니다.  또한, lockless_dereference() 은 RCU 와 함께
-     사용될수도, RCU 없이 사용될 수도 있는 일부 데이터 구조에 사용되고
-     있습니다.
-
-
  (*) dma_wmb();
  (*) dma_rmb();