Re: [PATCH v7 3/6] MCS Lock: Move mcs_lock/unlock function into its own file

[Peter Zijlstra <peterz@infradead.org>]

On Thu, Jan 16, 2014 at 04:08:24PM -0800, Tim Chen wrote:
> copy to kernel/locking/mcs_spinlock.c
> index 96f14299..44fb092 100644
> --- a/include/linux/mcs_spinlock.h
> +++ b/kernel/locking/mcs_spinlock.c
> +/*
> + * asm/processor.h may define arch_mutex_cpu_relax().
> + * If it is not defined, cpu_relax() will be used.
> + */
> +#include <asm/barrier.h>
> +#include <asm/cmpxchg.h>
> +#include <asm/processor.h>
> +#include <linux/compiler.h>
> +#include <linux/mcs_spinlock.h>
> +#include <linux/export.h>
>  
> +#ifndef arch_mutex_cpu_relax
> +# define arch_mutex_cpu_relax() cpu_relax()
> +#endif

Why not include <linux/mutex.h> to obtain arch_mutex_cpu_relax() ?

Now you have duplicated the definition, and in a file unrelated to its
name 'mutex'.

Now, arguable, we should maybe look at renaming the thing now that its
used outside of mutices, but whatever we do, I think its sane to keep a
single 'generic' definition.

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