From mboxrd@z Thu Jan  1 00:00:00 1970
From: Heiko Carstens <heiko.carstens@de.ibm.com>
Subject: Re: [patch 2/3] spinlock: allow inlined spinlocks
Date: Sun, 16 Aug 2009 20:44:58 +0200
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To: Ingo Molnar <mingo@elte.hu>
Cc: Andrew Morton <akpm@linux-foundation.org>, Linus Torvalds <torvalds@linux-foundation.org>, Peter Zijlstra <a.p.zijlstra@chello.nl>, linux-arch@vger.kernel.org, Martin Schwidefsky <schwidefsky@de.ibm.com>, Arnd Bergmann <arnd@arndb.de>, Horst Hartmann <horsth@linux.vnet.ibm.com>, Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>, Nick Piggin <nickpiggin@yahoo.com.au>

On Sun, Aug 16, 2009 at 08:06:31PM +0200, Ingo Molnar wrote:
> * Heiko Carstens <heiko.carstens@de.ibm.com> wrote:
> > > #define __spin_lock_is_small
> 
> > > +unsigned long __lockfunc _spin_lock_irqsave_nested(spinlock_t *lock, int subclass)
> > > +							__acquires(lock);
> > > +
> > > +#ifdef __spin_lock_is_small
> > > +#define _spin_lock(lock) __spin_lock(lock)
> > > +#else
> > > +void __lockfunc _spin_lock(spinlock_t *lock)		__acquires(lock);
> > > +#endif
> 
> Dunno - i'm somewhat wary of introducing a 2^28 variability here. 
> (although the number of real variations is much lower - but still).
> 
> What's the current situation on s390, precisely which of the 28 lock 
> functions are a win to be inlined and which ones are a loss? Do you 
> have a list/table perhaps?

No list unfortunately. However, the variants we really care about are
only the spin_locks. The *try_lock variants are also not that important.
So we end up with eight ifdefs (spin_lock/bh/irq/irq_save + unlock).

I'll change the patches according to Linus' comments and send them
again.