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Date: Mon, 05 Mar 2007 18:37:08 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Davide Libenzi <davidel@xmailserver.org>
CC: Linus Torvalds <torvalds@linux-foundation.org>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       Eric Dumazet <dada1@cosmosbay.com>
Subject: Re: [patch v2] epoll use a single inode ...
References: <Pine.LNX.4.64.0703051532590.4907@alien.or.mcafeemobile.com> <Pine.LNX.4.64.0703051558070.3998@woody.linux-foundation.org> <Pine.LNX.4.64.0703051609430.4907@alien.or.mcafeemobile.com> <Pine.LNX.4.64.0703051621590.3998@woody.linux-foundation.org> <45ECD122.6020907@zytor.com> <Pine.LNX.4.64.0703051832260.4907@alien.or.mcafeemobile.com>
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Davide Libenzi wrote:
> 
> Right now is using:
> 
> 	this.len = sprintf(name, "[%u.%d]", current->pid, fd);
> 
> That should be unique and not have the wraparound problem. Ack?
> 

NAK, very much NAK.

File descriptors aren't file structures, they're *pointers* to file 
structures.

It's perfectly possible -- downright common -- for a file descriptor to 
be inherited by another process, and then the pid is recycled -- collision.

	-hpa