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Subject: Re: [PATCH v3] timer: implement lockdep deadlock detection
From: Peter Zijlstra <peterz@infradead.org>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
       Linux Kernel list <linux-kernel@vger.kernel.org>
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Date: Thu, 29 Jan 2009 14:38:07 +0100
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On Wed, 2009-01-28 at 19:06 +0100, Johannes Berg wrote:

> +/*
> + * All the indirection here is required to build the
> + * "<file>:<line>" string and the pointer to it.
> + */
> +#define ___TIMER_INITIALIZER(_fn, _exp, _dat, _kn)			\
> +	____TIMER_INITIALIZER(_fn, _exp, _dat, (_kn), &(_kn))
> +#define __TIMER_INITIALIZER(_fn, _exp, _dat, _f, _c, _l)		\
> +	___TIMER_INITIALIZER(_fn, _exp, _dat, _f # _c # _l)
> +#define _TIMER_INITIALIZER(_fn, _exp, _dat, _f, _l)			\
> +	__TIMER_INITIALIZER(_fn, _exp, _dat, _f, :, _l)
> +#define TIMER_INITIALIZER(_function, _expires, _data)			\
> +	_TIMER_INITIALIZER(_function, _expires, _data, __FILE__, __LINE__)

The regular way to write that would be:

#define __STR(foo) #foo
#define STR(foo) __STR(foo)

__FILE__ ":" STR(__LINE__)

I'm sure I saw that stringify thing somewhere in the kernel before, but
can't find it. I recently added it to lockdep.c, maybe we should add it
to kernel.h ?