linux-kernel - Re: [PATCH 09/23] lib: percpu_counter

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Message-ID: <20070823182455.GB1608@filer.fsl.cs.sunysb.edu>
Date:	Thu, 23 Aug 2007 14:24:55 -0400
From:	Josef Sipek <jsipek@....cs.sunysb.edu>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	miklos@...redi.hu, akpm@...ux-foundation.org, neilb@...e.de,
	dgc@....com, tomoki.sekiyama.qu@...achi.com, nikita@...sterfs.com,
	trond.myklebust@....uio.no, yingchao.zhou@...il.com,
	richard@....demon.co.uk, torvalds@...ux-foundation.org
Subject: Re: [PATCH 09/23] lib: percpu_counter_init error handling

On Sat, Aug 18, 2007 at 10:09:34AM +0200, Peter Zijlstra wrote:
> On Fri, 2007-08-17 at 11:56 -0400, Josef Sipek wrote:
> > On Thu, Aug 16, 2007 at 09:45:34AM +0200, Peter Zijlstra wrote:
 
Sorry...this mail got lost in the flood of email after a procmail rule
stopped working...

> The actual value of err is irrelevant, it is not used after this not
> zero check.
> 
> But how about this:
> ---
> Subject: lib: percpu_counter_init error handling
> 
> alloc_percpu can fail, propagate that error.
> 
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> ---
>  fs/ext2/super.c                |   15 ++++++++++++---
>  fs/ext3/super.c                |   21 +++++++++++++++------
>  fs/ext4/super.c                |   21 +++++++++++++++------
>  include/linux/percpu_counter.h |    5 +++--
>  lib/percpu_counter.c           |    8 +++++++-
>  5 files changed, 52 insertions(+), 18 deletions(-)
> 
> Index: linux-2.6/fs/ext2/super.c
> ===================================================================
> --- linux-2.6.orig/fs/ext2/super.c
> +++ linux-2.6/fs/ext2/super.c
> @@ -725,6 +725,7 @@ static int ext2_fill_super(struct super_
>  	int db_count;
>  	int i, j;
>  	__le32 features;
> +	int err;
>  
>  	sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
>  	if (!sbi)
> @@ -996,12 +997,20 @@ static int ext2_fill_super(struct super_
>  	sbi->s_rsv_window_head.rsv_goal_size = 0;
>  	ext2_rsv_window_add(sb, &sbi->s_rsv_window_head);
>  
> -	percpu_counter_init(&sbi->s_freeblocks_counter,
> +	err = percpu_counter_init(&sbi->s_freeblocks_counter,
>  				ext2_count_free_blocks(sb));
> -	percpu_counter_init(&sbi->s_freeinodes_counter,
> +	if (!err) {
> +		err = percpu_counter_init(&sbi->s_freeinodes_counter,
>  				ext2_count_free_inodes(sb));
> -	percpu_counter_init(&sbi->s_dirs_counter,
> +	}
> +	if (!err) {
> +		err = percpu_counter_init(&sbi->s_dirs_counter,
>  				ext2_count_dirs(sb));
> +	}
> +	if (err) {
> +		printk(KERN_ERR "EXT2-fs: insufficient memory\n");
> +		goto failed_mount3;
> +	}
>  	/*
>  	 * set up enough so that it can read an inode
>  	 */

I find this more readable as I don't have to try to figure out what the
bitops are doing :)

Jeff.

-- 
Mankind invented the atomic bomb, but no mouse would ever construct a
mousetrap.
		- Albert Einstein
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