Re: dealing with excessive includes

[Linus Torvalds <torvalds@osdl.org>]

On Wed, 18 Oct 2006, Al Viro wrote:
>
> +#define lock_super(x) do {		\
> +	struct super_block *sb = x;	\
> +	get_fs_excl();			\
> +	mutex_lock(&sb->s_lock);	\
> +} while(0)

Don't do this. The "x" passed in may be "sb", and then you end up with 
bogus code.

I think the solution to these kinds of things is either
 - just bite the bullet, and make it out-of-line. A function call isn't 
   that expensive, and is sometimes actually cheaper due to I$ issues.
 - have a separate trivial header file, and only include it for people who 
   actually need these things (very few files, actually - it's usually 
   just one file per filesystem)

In this case, since it's _so_ simple, and since it's _so_ specialized, I 
think #2 is the right one. Normally, uninlining would be.

		Linus
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