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From: Peter Zijlstra <peterz@infradead.org>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Joel Fernandes <joel@joelfernandes.org>,
	linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Will Deacon <will@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"Paul E . McKenney" <paulmck@kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Lai Jiangshan <jiangshanlai@gmail.com>,
	Josh Triplett <josh@joshtriplett.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	rcu@vger.kernel.org
Subject: Re: [PATCH 3/8] srcu: Use local_lock() for per-CPU struct srcu_data access
Date: Wed, 20 May 2020 20:35:29 +0200
Message-ID: <20200520183529.GR317569@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200520182800.sdp6t6bgbhn4kkqk@linutronix.de>

On Wed, May 20, 2020 at 08:28:00PM +0200, Sebastian Andrzej Siewior wrote:
> On 2020-05-20 13:42:59 [-0400], Joel Fernandes wrote:
> > Hi Sebastian,
> Hi Joel,
> 
> > For pointer stability, can we just use get_local_ptr() and put_local_ptr()
> > instead of adding an extra lock? This keeps the pointer stable while keeping
> > the section preemptible on -rt. And we already have a lock in rcu_data, I
> > prefer not to add another lock if possible.
> 
> What is this get_local_ptr() doing? I can't find it anywhere…

I suspect it is ({ preempt_disable(); this_cpu_ptr(ptr); }), or
something along those lines.

But yeah, I can't find it either.

  reply index

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20200519201912.1564477-1-bigeasy@linutronix.de>
2020-05-19 20:19 ` Sebastian Andrzej Siewior
2020-05-20 10:24   ` Peter Zijlstra
2020-05-20 12:06     ` Sebastian Andrzej Siewior
2020-05-20 13:27       ` Peter Zijlstra
2020-05-20 17:42       ` Joel Fernandes
2020-05-20 18:28         ` Sebastian Andrzej Siewior
2020-05-20 18:35           ` Peter Zijlstra [this message]
2020-05-20 18:44             ` Joel Fernandes
2020-05-20 18:50               ` Uladzislau Rezki
2020-05-20 18:59           ` Joel Fernandes
2020-05-20 18:43       ` Paul E. McKenney
2020-05-22 15:12         ` Sebastian Andrzej Siewior
2020-05-22 17:39           ` Paul E. McKenney
2020-05-23 15:08             ` Sebastian Andrzej Siewior
2020-05-23 16:59               ` Paul E. McKenney
2020-05-24 19:03               ` Sebastian Andrzej Siewior
2020-05-25  3:27                 ` Paul E. McKenney
2020-05-26 13:41                   ` [PATCH] srcu: Avoid local_irq_save() before acquiring spinlock_t Sebastian Andrzej Siewior
2020-05-26 16:16                     ` Paul E. McKenney
2020-05-26 16:31                       ` Sebastian Andrzej Siewior

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