[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <20210106005407.12295-5-paulmck@kernel.org>
Date: Tue, 5 Jan 2021 16:54:04 -0800
From: paulmck@...nel.org
To: rcu@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, kernel-team@...com, mingo@...nel.org,
jiangshanlai@...il.com, akpm@...ux-foundation.org,
mathieu.desnoyers@...icios.com, josh@...htriplett.org,
tglx@...utronix.de, peterz@...radead.org, rostedt@...dmis.org,
dhowells@...hat.com, edumazet@...gle.com, fweisbec@...il.com,
oleg@...hat.com, joel@...lfernandes.org,
"Paul E. McKenney" <paulmck@...nel.org>
Subject: [PATCH tip/core/rcu 5/8] doc: Update RCU requirements RCU_INIT_POINTER() description
From: "Paul E. McKenney" <paulmck@...nel.org>
Back in the day, RCU_INIT_POINTER() was the only way to avoid
memory-barrier instructions while storing NULL to an RCU-protected
pointer. Fortunately, in 2016, rcu_assign_pointer() started checking for
compile-time NULL pointers and omitting the memory-barrier instructions in
that case. Unfortunately, RCU's Requirements.rst document was not updated
accordingly. This commit therefore at long last carries out that update.
Fixes: 3a37f7275cda ("rcu: No ordering for rcu_assign_pointer() of NULL")
Link: https://lore.kernel.org/lkml/20201209230755.GV7338@casper.infradead.org/
Reported-by: Matthew Wilcox <willy@...radead.org>
Acked-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
---
Documentation/RCU/Design/Requirements/Requirements.rst | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/Documentation/RCU/Design/Requirements/Requirements.rst b/Documentation/RCU/Design/Requirements/Requirements.rst
index f32f8fa..65c7839 100644
--- a/Documentation/RCU/Design/Requirements/Requirements.rst
+++ b/Documentation/RCU/Design/Requirements/Requirements.rst
@@ -1668,8 +1668,7 @@ against mishaps and misuse:
this purpose.
#. It is not necessary to use rcu_assign_pointer() when creating
linked structures that are to be published via a single external
- pointer. The RCU_INIT_POINTER() macro is provided for this task
- and also for assigning ``NULL`` pointers at runtime.
+ pointer. The RCU_INIT_POINTER() macro is provided for this task.
This not a hard-and-fast list: RCU's diagnostic capabilities will
continue to be guided by the number and type of usage bugs found in
--
2.9.5
Powered by blists - more mailing lists