Messages in this thread Patch in this message | | | From | paulmck@kernel ... | Subject | [PATCH tip/core/rcu 5/8] doc: Update RCU requirements RCU_INIT_POINTER() description | Date | Tue, 5 Jan 2021 16:54:04 -0800 |
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From: "Paul E. McKenney" <paulmck@kernel.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@infradead.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.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
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