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Date: Sat, 3 May 2003 09:54:31 +0530
From: Dipankar Sarma <dipankar@in.ibm.com>
To: Andrew Morton <akpm@digeo.com>
Cc: viro@parcelfarce.linux.theplanet.co.uk, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] reducing overheads in fget/fput
Message-ID: <20030503042431.GC1407@in.ibm.com>
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On Fri, May 02, 2003 at 09:00:03PM -0700, Andrew Morton wrote:
> Dipankar Sarma <dipankar@in.ibm.com> wrote:
> > Not sure what your grouse is, but I don't like the fget_ligth()/fput_light
> > semantics myself. They don't seem natural, but I can't think of
> > better way to do this. 
> 
> Precisely.

I thought of doing something like -

static inline is_fds_shared(void)
{
	struct files_struct *files = current->files;
	return atomic_read(&files->count) != 1;
}


sys_blah(..)
{

	int fds_shared = is_fds_shared();

	file = fget_light(fd, fds_shared);
	...
	...
	fput_light(file, fds_shared);
}

It still didn't look very natural. We leave open the possibility of
users doing is_fds_shared() for both fget_light and fput_light.
With fput_needed flag, atleast we force them to use what is returned
by fget_light.

Thanks
Dipankar