From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753383AbbJFQf7 (ORCPT ); Tue, 6 Oct 2015 12:35:59 -0400 Received: from e32.co.us.ibm.com ([32.97.110.150]:50717 "EHLO e32.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753088AbbJFQea (ORCPT ); Tue, 6 Oct 2015 12:34:30 -0400 X-IBM-Helo: d03dlp01.boulder.ibm.com X-IBM-MailFrom: paulmck@linux.vnet.ibm.com X-IBM-RcptTo: linux-kernel@vger.kernel.org From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 1/5] documentation: No acquire/release for RCU readers Date: Tue, 6 Oct 2015 09:34:18 -0700 Message-Id: <1444149262-14966-1-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 2.5.2 In-Reply-To: <20151006163358.GA14407@linux.vnet.ibm.com> References: <20151006163358.GA14407@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15100616-0005-0000-0000-000018BCA7EC Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Documentation/memory-barriers.txt calls out RCU as one of the sets of primitives associated with ACQUIRE and RELEASE. There really is an association in that rcu_assign_pointer() includes a RELEASE operation, but a quick read can convince people that rcu_read_lock() and rcu_read_unlock() have ACQUIRE and RELEASE semantics, which they do not. This commit therefore removes RCU from this list in order to avoid this confusion. Reported-by: Boqun Feng Signed-off-by: Paul E. McKenney --- Documentation/memory-barriers.txt | 1 - 1 file changed, 1 deletion(-) diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt index 2ba8461b0631..d336e4d42029 100644 --- a/Documentation/memory-barriers.txt +++ b/Documentation/memory-barriers.txt @@ -1789,7 +1789,6 @@ The Linux kernel has a number of locking constructs: (*) mutexes (*) semaphores (*) R/W semaphores - (*) RCU In all cases there are variants on "ACQUIRE" operations and "RELEASE" operations for each construct. These operations all imply certain barriers: -- 2.5.2