linux-kernel - Re: [RFC/PATCH] revokeat/frevoke system calls V5

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Message-Id: <4182E03E-A471-458C-98E6-4524C10BBE9A@mac.com>
Date:	Mon, 26 Feb 2007 16:36:05 -0500
From:	Kyle Moffett <mrmacman_g4@....com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Alan <alan@...rguk.ukuu.org.uk>, Zach Brown <zab@...bo.net>,
	Pekka Enberg <penberg@...helsinki.fi>,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	hch@....de
Subject: Re: [RFC/PATCH] revokeat/frevoke system calls V5

On Feb 26, 2007, at 13:46:21, H. Peter Anvin wrote:
> Alan wrote:
>>> I'm not sure.  Turning, for example, the statat(dir_fd, name ==  
>>> NULL)  error case into fstat(dir_fd) sounds like a way for apps,  
>>> admittedly  buggy ones, to be surprised.  Maybe libc would be  
>>> exptected to catch  the error before performing the shared system  
>>> call?
>> At that point would it not be cheaper to have two system calls,  
>> the table cost isn't very large.
>
> It's not just the table, though, you need two entry points, but  
> even that isn't really all that big either, I guess.

Well, I suppose there are multiple possibilities for consolidation:
   frevokeat(fd, "/foo/bar/baz") => normal frevokeat
   frevokeat(-1, "/foo/bar/baz")	=> revoke("/foo/bar/baz");
   frevokeat(fd, NULL)		=> frevoke(fd);

Neither of those would ordinarily be considered to do anything useful  
and for new syscalls I can't see the possibility of breaking existing  
programs.  On the other hand, it's not like we have any problems with  
the syscall tables getting too large.

Cheers,
Kyle Moffett

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