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From: Dean Nelson <dcn@sgi.com>
To: Al Viro <viro@ftp.linux.org.uk>
Cc: akpm@linux-foundation.org, linux-ia64@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	tony.luck@intel.com, jes@sgi.com
Subject: Re: [PATCH 1/4] export __put_task_struct for XPMEM
Date: Mon, 27 Aug 2007 13:10:56 -0500	[thread overview]
Message-ID: <20070827181056.GA30176@sgi.com> (raw)
In-Reply-To: <20070827161327.GG21089@ftp.linux.org.uk>

On Mon, Aug 27, 2007 at 05:13:28PM +0100, Al Viro wrote:
> On Mon, Aug 27, 2007 at 10:59:33AM -0500, Dean Nelson wrote:
> > This patch exports __put_task_struct as it is needed by XPMEM.
> > 
> > Signed-off-by: Dean Nelson <dcn@sgi.com>
> > 
> > ---
> > 
> > One struct file_operations registered by XPMEM, xpmem_open(), calls
> > 'get_task_struct(current->group_leader)' and another, xpmem_flush(), calls
> > 'put_task_struct(tg->group_leader)'.
> 
> Does it?  Well, then open the file in question and start doing close(dup(fd))
> in a loop.  Won't take long for an oops...

Actually it won't oops. And that's because when the file is opened,
xpmem_open() creates a structure for that thread group, and when
xpmem_flush() is called on the close() it first looks for that structure
and if it finds it then it does what it needs to do (which includes the
put_task_struct() call) and then finishes off by destroying the structure.
So for subsequent closes xpmem_flush() returns without calling
put_task_struct().

  reply	other threads:[~2007-08-27 18:11 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-08-27 15:56 [PATCH 0/4] SGI Altix cross partition memory (XPMEM) Dean Nelson
2007-08-27 15:59 ` [PATCH 1/4] export __put_task_struct for XPMEM Dean Nelson
2007-08-27 16:13   ` Al Viro
2007-08-27 18:10     ` Dean Nelson [this message]
2007-08-27 18:15       ` Al Viro
2007-08-27 19:19         ` Dean Nelson
2007-08-27 19:35           ` Al Viro
2007-08-27 20:24             ` Robin Holt
2007-08-27 20:47               ` Al Viro
2007-08-28 18:01       ` Christoph Hellwig
2007-08-27 16:01 ` [PATCH 2/4] export zap_page_range " Dean Nelson
2007-08-27 16:02 ` [PATCH 3/4] add new lock ordering rule to mm/filemap.c Dean Nelson
2007-08-27 16:41 ` [PATCH 4/4] add SGI Altix cross partition memory (XPMEM) driver Dean Nelson
2007-08-27 20:00   ` Adrian Bunk
2007-08-28 18:02   ` Christoph Hellwig
2007-08-28 19:00     ` Robin Holt
2007-08-28 19:05       ` Christoph Hellwig

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