From: Frederic Weisbecker <frederic@kernel.org>
To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Boqun Feng <boqun.feng@gmail.com>,
Joel Fernandes <joel@joelfernandes.org>,
Neeraj Upadhyay <neeraj.upadhyay@amd.com>,
Uladzislau Rezki <urezki@gmail.com>,
Zqiang <qiang.zhang1211@gmail.com>, rcu <rcu@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 2/2] rcu/tasks: Further comment ordering around current task snapshot on TASK-TRACE
Date: Tue, 21 May 2024 11:59:57 +0200 [thread overview]
Message-ID: <ZkxwnZacvXqfHxZD@localhost.localdomain> (raw)
In-Reply-To: <24467166-5f00-45f2-867f-40b8a836d085@paulmck-laptop>
Le Mon, May 20, 2024 at 04:25:33PM -0700, Paul E. McKenney a écrit :
> Good points! How about the following?
>
> // Note that cpu_curr_snapshot() picks up the target
> // CPU's current task while its runqueue is locked with
> // an smp_mb__after_spinlock(). This ensures that either
> // the grace-period kthread will see that task's read-side
> // critical section or the task will see the updater's pre-GP
> // accesses. The trailng smp_mb() in cpu_curr_snapshot()
*trailing
> // does not currently play a role other than simplify
> // that function's ordering semantics. If these simplified
> // ordering semantics continue to be redundant, that smp_mb()
> // might be removed.
>
> Keeping in mind that the commit's log fully lays out the troublesome
> scenario.
Yep, looks very good!
Thanks!
>
> Thanx, Paul
>
next prev parent reply other threads:[~2024-05-21 10:00 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-17 15:23 [PATCH 0/2] rcu/tasks: Fix stale task snapshot Frederic Weisbecker
2024-05-17 15:23 ` [PATCH 1/2] rcu/tasks: Fix stale task snaphot from TASK-TRACE Frederic Weisbecker
2024-05-17 23:30 ` Paul E. McKenney
2024-05-17 15:23 ` [PATCH 2/2] rcu/tasks: Further comment ordering around current task snapshot on TASK-TRACE Frederic Weisbecker
2024-05-20 18:48 ` Paul E. McKenney
2024-05-20 20:41 ` Frederic Weisbecker
2024-05-20 23:25 ` Paul E. McKenney
2024-05-21 9:59 ` Frederic Weisbecker [this message]
2024-05-21 13:38 ` Paul E. McKenney
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