linux-kernel - Re: [PATCH] sched: Change READ

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Message-ID: <20160926085547.GJ5012@twins.programming.kicks-ass.net>
Date:   Mon, 26 Sep 2016 10:55:47 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Bart Van Assche <bart.vanassche@...disk.com>
Cc:     Ingo Molnar <mingo@...hat.com>, Oleg Nesterov <oleg@...hat.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] sched: Change READ_ONCE(jiffies) into jiffies

On Sun, Sep 25, 2016 at 07:08:45PM -0700, Bart Van Assche wrote:
> A quote from Documentation/memory_barriers.txt:
> 
> For example, because 'jiffies' is marked volatile, it is never
> necessary to say READ_ONCE(jiffies).  The reason for this is
> that READ_ONCE() and WRITE_ONCE() are implemented as volatile
> casts, which has no effect when its argument is already marked
> volatile.
> 
> Hence change all 'READ_ONCE(jiffies)' occurrences into 'jiffies'.

So I'm not a huge fan of this patch. Yes its technically pointless, but
it does convey intent. See the READ_ONCE() as a comment if you will.