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From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Eric Dumazet <dada1@cosmosbay.com>
Cc: Christoph Hellwig <hch@infradead.org>,
	linux-kernel@vger.kernel.org, akpm@osdl.org
Subject: Re: [PATCH] reduce sizeof(struct file)
Date: Sun, 25 Sep 2005 11:43:30 +1000	[thread overview]
Message-ID: <433600C2.6020007@yahoo.com.au> (raw)
In-Reply-To: <4334CB49.3080703@cosmosbay.com>

Eric Dumazet wrote:

> --- linux-2.6.14-rc2-orig/include/linux/fs.h	2005-09-20 05:00:41.000000000 +0200
> +++ linux-2.6.14-rc2/include/linux/fs.h	2005-09-24 04:52:20.000000000 +0200
> @@ -574,7 +574,13 @@
>  #define RA_FLAG_INCACHE 0x02	/* file is already in cache */
>  
>  struct file {
> -	struct list_head	f_list;
> +/*
> + * f_list and f_rcuhead can share the same memory location
> + */
> +	union {
> +		struct list_head	fu_list;
> +		struct rcu_head 	fu_rcuhead;
> +		} f_u;

I don't think you need to explain this basic C semantic to
the reader if they have gotten this far ;)

Instead, explain when fu_list and fu_rcuhead are used.
Something along the lines of

/*
  * fu_list becomes invalid after file_free is called
  * and queued via fu_rcuhead for RCU freeing
  */

Nick

-- 
SUSE Labs, Novell Inc.

Send instant messages to your online friends http://au.messenger.yahoo.com 

  reply	other threads:[~2005-09-25  1:43 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-09-23  8:34 How to Force PIO mode on sata promise (Linux 2.6.10) David Sanchez
2005-09-23  9:47 ` Clemens Koller
2005-09-23 10:02   ` [PATCH] reduce sizeof(struct file) Eric Dumazet
2005-09-23 10:05     ` Christoph Hellwig
2005-09-23 23:30       ` J.A. Magallon
2005-09-24  0:09         ` Jesper Juhl
2005-09-24  0:19         ` Al Viro
2005-09-24  3:43       ` Eric Dumazet
2005-09-25  1:43         ` Nick Piggin [this message]
2005-09-30  0:32         ` Paul E. McKenney

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