Date: Fri, 22 Feb 2008 08:46:16 -0500 (EST)
From: Steven Rostedt <rostedt@goodmis.org>
To: Ingo Molnar <mingo@elte.hu>
cc: gregory.haskins@gmail.com, Gregory Haskins <ghaskins@novell.com>,
       a.p.zijlstra@chello.nl, tglx@linutronix.de,
       linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org,
       bill.huey@gmail.com, kevin@hilman.org, cminyard@mvista.com,
       dsingleton@mvista.com, dwalker@mvista.com, npiggin@suse.de,
       dsaxena@plexity.net, ak@suse.de, gregkh@suse.de, sdietrich@novell.com,
       pmorreale@novell.com, mkohari@novell.com
Subject: Re: [PATCH [RT] 05/14] rearrange rt_spin_lock sleep
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Gregory,

I guess we should have just read Documentation/memory-barriers.text

Here's the snippet:


Any atomic operation that modifies some state in memory and returns
information
about the state (old or new) implies an SMP-conditional general memory
barrier
(smp_mb()) on each side of the actual operation (with the exception of
explicit lock operations, described later).  These include:

        xchg();
        cmpxchg();
        atomic_cmpxchg();
        atomic_inc_return();
        atomic_dec_return();
        atomic_add_return();
        atomic_sub_return();
        atomic_inc_and_test();
        atomic_dec_and_test();
        atomic_sub_and_test();
        atomic_add_negative();
        atomic_add_unless();
        test_and_set_bit();
        test_and_clear_bit();
        test_and_change_bit();


-- Steve

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