From mboxrd@z Thu Jan  1 00:00:00 1970
From: sukadev-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org
Subject: Re: [RFC][PATCH 1/3] Move parts of init_dev() into new functions
Date: Mon, 25 Aug 2008 18:18:07 -0700
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To: "H. Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>
Cc: kyle-hoO6YkzgTuCM0SS3m2neIg@public.gmane.org, bastian-yyjItF7Rl6lg9hUCZPvPmw@public.gmane.org, containers-qjLDD68F18O7TbgM5vRIOg@public.gmane.org, xemul-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org, Alan Cox <alan-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org>, ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org
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H. Peter Anvin [hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org] wrote:
> sukadev-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org wrote:
>>>
>>> 	tty = driver->ops->get_tty(driver, inode [, other_stuff?]);
>> Can the inode be used to identify the driver too ?  (but inode to driver
>> mapping is not trivial atm).
>
> It can, but it's an O(n) operation in the number of registered drivers.  
> However, we can only call the above if we know the driver in the first 
> place so such a lookup is rather pointless.

Yes, we know the driver, but do we need to pass it into ->get_tty() ?

Passing it in (or having the operation compute from inode) has advantage
of allowing drivers to share code if necessary.

	common_get_tty(driver, inode)
	{
		if (is_ptmx_driver(driver))
			something;
		else // pts driver
			something_else;
	}