From: "Paul E. McKenney" <paulmck@kernel.org>
To: frederic@kernel.org
Cc: boqun.feng@gmail.com, rcu@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: One potential issue with concurrent execution of RCU callbacks...
Date: Tue, 8 Dec 2020 06:58:10 -0800 [thread overview]
Message-ID: <20201208145810.GA4875@paulmck-ThinkPad-P72> (raw)
Hello, Frederic,
Boqun just asked if RCU callbacks ran in BH-disabled context to avoid
concurrent execution of the same callback. Of course, this raises the
question of whether a self-posting callback can have two instances of
itself running concurrently while a CPU is in the process of transitioning
between softirq and rcuo invocation of callbacks.
I believe that the answer is "no" because BH-disabled context is
an implicit RCU read-side critical section. Therefore, the initial
invocation of the RCU callback must complete in order for a new grace
period to complete, and a new grace period must complete before the
second invocation of that same callback to start.
Does that make sense, or am I missing something?
Thanx, Paul
next reply other threads:[~2020-12-08 14:58 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-08 14:58 Paul E. McKenney [this message]
2020-12-08 15:54 ` One potential issue with concurrent execution of RCU callbacks Frederic Weisbecker
2020-12-08 17:19 ` Paul E. McKenney
2020-12-08 17:52 ` Frederic Weisbecker
2020-12-08 18:24 ` Paul E. McKenney
2020-12-08 22:04 ` Frederic Weisbecker
2020-12-09 0:03 ` Paul E. McKenney
2020-12-09 2:14 ` Boqun Feng
2020-12-10 0:50 ` Paul E. McKenney
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