Re: [PATCH] Fix add missing include guard

[Peter Zijlstra]

On Sun, Sep 07, 2014 at 09:42:36PM +0530, Anand Moon wrote:
> If a header file happens to be included twice, the compiler will process
> its contents twice. This is very likely to cause an error, e.g. when the
> compiler sees the same structure definition twice. Even if it does not,
> it will certainly waste time.



> --- a/kernel/locking/lockdep_states.h
> +++ b/kernel/locking/lockdep_states.h
> @@ -4,6 +4,12 @@
>   * please update XXX_LOCK_USAGE_STATES in include/linux/lockdep.h whenever
>   * you add one, or come up with a nice dynamic solution.
>   */
> +
> +#ifndef __LOCKDEPSTATE_H__
> +#define __LOCKDEPSTATE_H__
> +
>  LOCKDEP_STATE(HARDIRQ)
>  LOCKDEP_STATE(SOFTIRQ)
>  LOCKDEP_STATE(RECLAIM_FS)
> +
> +#endif /* __LOCKDEPSTATE_H__ */


That file is actually designed to be included multiple times; you
clearly didn't understand what you were doing.
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