linux-kernel - Re: [PATCH 1/2] ext2: Reduce object size when !CONFIG

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Message-ID: <20130621165049.GP13932@quack.suse.cz>
Date:	Fri, 21 Jun 2013 18:50:49 +0200
From:	Jan Kara <jack@...e.cz>
To:	Joe Perches <joe@...ches.com>
Cc:	linux-ext4@...r.kernel.org, Theodore Ts'o <tytso@....edu>,
	Jan Kara <jack@...e.cz>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] ext2: Reduce object size when !CONFIG_PRINTK

On Tue 18-06-13 10:14:39, Joe Perches wrote:
> Reducing the object size ~5kb/15% could be useful for embedded
> systems.
> 
> Add #ifdef CONFIG_PRINTK #else #endif blocks
> to hold formats and arguments, passing " " to
> functions when !CONFIG_PRINTK and still verifying
> format and arguments with no_printk.
> 
>  $ size fs/ext2/built-in.o*
>     text   data	    bss	    dec	    hex	filename
>    31297     44	      4	  31345	   7a71	fs/ext2/built-in.o.ext2.new
>    36288     44	      4	  36336	   8df0	fs/ext2/built-in.o.ext2.old
> 
>  $ grep -E "CONFIG_EXT2|CONFIG_PRINTK" .config
>  # CONFIG_PRINTK is not set
>  CONFIG_EXT2_FS=y
>  # CONFIG_EXT2_FS_XATTR is not set
>  # CONFIG_EXT2_FS_XIP is not set
  I'm somewhat reluctant to merge this unless I know someone really
cares. It looks a bit ugly to ifdef every function doing some printing just
to reduce object size when CONFIG_PRINTK is disabled... And in future LTO
might help us ;)

								Honza

> 
> Signed-off-by: Joe Perches <joe@...ches.com>
> ---
>  fs/ext2/ext2.h  | 22 ++++++++++++++++++++--
>  fs/ext2/super.c |  6 +++---
>  2 files changed, 23 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
> index d9a17d0..888ae31 100644
> --- a/fs/ext2/ext2.h
> +++ b/fs/ext2/ext2.h
> @@ -767,12 +767,30 @@ struct dentry *ext2_get_parent(struct dentry *child);
>  
>  /* super.c */
>  extern __printf(3, 4)
> -void ext2_error(struct super_block *, const char *, const char *, ...);
> +void __ext2_error(struct super_block *, const char *, const char *, ...);
>  extern __printf(3, 4)
> -void ext2_msg(struct super_block *, const char *, const char *, ...);
> +void __ext2_msg(struct super_block *, const char *, const char *, ...);
>  extern void ext2_update_dynamic_rev (struct super_block *sb);
>  extern void ext2_write_super (struct super_block *);
>  
> +#ifdef CONFIG_PRINTK
> +#define ext2_error(sb, func, fmt, ...)					\
> +	__ext2_error(sb, func, fmt, ##__VA_ARGS__)
> +#define ext2_msg(sb, prefix, fmt, ...)					\
> +	__ext2_msg(sb, prefix, fmt, ##__VA_ARGS__)
> +#else
> +#define ext2_error(sb, func, fmt, ...)					\
> +do {									\
> +	no_printk(fmt, ##__VA_ARGS__);					\
> +	__ext2_error(sb, func, " ");					\
> +} while (0)
> +#define ext2_msg(sb, prefix, fmt, ...)					\
> +do {									\
> +	no_printk(fmt, ##__VA_ARGS__);					\
> +	__ext2_msg(sb, prefix, " ");					\
> +} while (0)
> +#endif
> +
>  /*
>   * Inodes and files operations
>   */
> diff --git a/fs/ext2/super.c b/fs/ext2/super.c
> index 2885349..61ffb3f 100644
> --- a/fs/ext2/super.c
> +++ b/fs/ext2/super.c
> @@ -45,8 +45,8 @@ static int ext2_sync_fs(struct super_block *sb, int wait);
>  static int ext2_freeze(struct super_block *sb);
>  static int ext2_unfreeze(struct super_block *sb);
>  
> -void ext2_error(struct super_block *sb, const char *function,
> -		const char *fmt, ...)
> +void __ext2_error(struct super_block *sb, const char *function,
> +		  const char *fmt, ...)
>  {
>  	struct va_format vaf;
>  	va_list args;
> @@ -80,7 +80,7 @@ void ext2_error(struct super_block *sb, const char *function,
>  	}
>  }
>  
> -void ext2_msg(struct super_block *sb, const char *prefix,
> +void __ext2_msg(struct super_block *sb, const char *prefix,
>  		const char *fmt, ...)
>  {
>  	struct va_format vaf;
> -- 
> 1.8.1.2.459.gbcd45b4.dirty
> 
-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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