Date: Thu, 14 Feb 2008 11:11:43 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: minyard@acm.org
Cc: Linux Kernel <linux-kernel@vger.kernel.org>,
       OpenIPMI Developers <openipmi-developer@lists.sourceforge.net>,
       Konstantin Baydarov <kbaidarov@ru.mvista.com>
Subject: Re: [PATCH 3/4] IPMI: convert locked counters to atomics
Message-Id: <20080214111143.7e0937ea.akpm@linux-foundation.org>
In-Reply-To: <20080214183051.GC20148@minyard.local>
References: <20080214183051.GC20148@minyard.local>
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> +	for (i = 0; i < IPMI_NUM_STATS; i++)
> +		atomic_set(&intf->stats[i], 0);

And this is why it would be very hard for any architecture to ever
implement atomic_t as

struct atomic_t {
	int counter;
	spinlock_t lock;
};

The interface assumes that atomic_set() fully initialises the atomic_t, and
that atomic_set() can be used agaisnt both an uninitialised atomic_t and
against an already-initialised atomic_t.  IOW, we don't have atomic_init().

So would our hypothetical future architcture's atomic_set() do spin_lock(),
or would it do spin_lock_init()?  Either one is wrong in many atomic_set
callsites.

Oh well.
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