Re: [PATCH 3/4] IPMI: convert locked counters to atomics

From: Corey Minyard
Date: Thu Feb 14 2008 - 15:14:23 EST


Andrew Morton wrote:
+ 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.
Yeah, I thought the same thing when I did this. Do we start working
on an atomic_init()? It would be easy enough to set it to atomic_set()
for current architectures.

-corey
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