linux-kernel - [RFC 0/2] srcu: Remove pre-flip memory barrier

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Message-Id: <20221218191310.130904-1-joel@joelfernandes.org>
Date:   Sun, 18 Dec 2022 19:13:07 +0000
From:   "Joel Fernandes (Google)" <joel@...lfernandes.org>
To:     linux-kernel@...r.kernel.org
Cc:     "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        Josh Triplett <josh@...htriplett.org>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        "Paul E. McKenney" <paulmck@...nel.org>, rcu@...r.kernel.org,
        Steven Rostedt <rostedt@...dmis.org>
Subject: [RFC 0/2] srcu: Remove pre-flip memory barrier

Hello, I believe the pre-flip memory barrier is not required. The only reason I
can say to remove it, other than the possibility that it is unnecessary, is to
not have extra code that does not help. However, since we are issuing a fully
memory-barrier after the flip, I cannot say that it hurts to do it anyway.

For this reason, please consider these patches as "informational", than a
"please merge". :-) Though, feel free to consider merging if you agree!

All SRCU scenarios pass with these, with 6 hours of testing.

thanks,

 - Joel

Joel Fernandes (Google) (2):
srcu: Remove comment about prior read lock counts
srcu: Remove memory barrier "E" as it is not required

kernel/rcu/srcutree.c | 10 ----------
1 file changed, 10 deletions(-)

--
2.39.0.314.g84b9a713c41-goog