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Date:   Fri, 28 Jun 2019 18:07:40 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     John Ogness <john.ogness@linutronix.de>
Cc:     linux-kernel@vger.kernel.org, Petr Mladek <pmladek@suse.com>,
        Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Andrea Parri <andrea.parri@amarulasolutions.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Subject: Re: [RFC PATCH v2 1/2] printk-rb: add a new printk ringbuffer
 implementation
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On Fri, Jun 28, 2019 at 05:44:35PM +0200, Peter Zijlstra wrote:
> On Fri, Jun 28, 2019 at 11:50:33AM +0200, John Ogness wrote:

> > cmpxchg_release() vs WRITE_ONCE() is not safe?! Can you point me to
> > documentation about this?
> 
> Documentation/atomic_t.txt has this, see the SEMANTICS section on
> atomic-set.

Also see: arch/parisc/lib/bitops.c for one such case.